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Humans (''Homo sapiens'') are the most abundant and widespread
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter including ...
, characterized by
bipedalism Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...
and exceptional cognitive skills due to a large and complex
brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
. This has enabled the development of advanced tools,
culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
, and
language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...
. Humans are highly social and tend to live in complex
social structure In the social sciences, social structure is the aggregate of patterned social arrangements in society that are both emergent from and determinant of the actions of individuals. Likewise, society is believed to be grouped into structurally rel ...
s composed of many cooperating and competing groups, from
families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...
and kinship networks to political states. Social interactions between humans have established a wide variety of values,
social norms Social norms are shared standards of acceptable behavior by groups. Social norms can both be informal understandings that govern the behavior of members of a society, as well as be codified into rules and laws. Social normative influences or soci ...
, and
ritual A ritual is a sequence of activities involving gestures, words, actions, or objects, performed according to a set sequence. Rituals may be prescribed by the traditions of a community, including a religious community. Rituals are characterized ...
s, which bolster human
society A society is a group of individuals involved in persistent social interaction, or a large social group sharing the same spatial or social territory, typically subject to the same political authority and dominant cultural expectations. Soci ...
. Its
intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can be des ...
and its desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of
science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earli ...
, philosophy,
mythology Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. Since "myth" is widely used to imply that a story is not objectively true, the identification of a narra ...
,
religion Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, ...
, and other
fields of study Fields may refer to: Music * Fields (band), an indie rock band formed in 2006 * Fields (progressive rock band), a progressive rock band formed in 1971 * ''Fields'' (album), an LP by Swedish-based indie rock band Junip (2010) * "Fields", a song b ...
. Although some scientists equate the term ''humans'' with all members of the genus ''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...
'', in common usage, it generally refers to ''Homo sapiens'', the only extant member.
Anatomically modern human Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
s emerged around 300,000 years ago in Africa, evolving from ''
Homo heidelbergensis ''Homo heidelbergensis'' (also ''H. sapiens heidelbergensis''), sometimes called Heidelbergs, is an extinct species or subspecies of archaic human which existed during the Middle Pleistocene. It was subsumed as a subspecies of '' H. erectus'' i ...
'' or a similar species and migrating
out of Africa ''Out of Africa'' is a memoir by the Danish author Karen Blixen. The book, first published in 1937, recounts events of the seventeen years when Blixen made her home in Kenya, then called British East Africa. The book is a lyrical meditation on ...
, gradually replacing or
interbreeding In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...
with local populations of archaic humans. For most of history, humans were
nomadic A nomad is a member of a community without fixed habitation who regularly moves to and from the same areas. Such groups include hunter-gatherers, pastoral nomads (owning livestock), tinkers and trader nomads. In the twentieth century, the popu ...
hunter-gatherers. Humans began exhibiting
behavioral modernity Behavioral modernity is a suite of behavioral and cognitive traits that distinguishes current '' Homo sapiens'' from other anatomically modern humans, hominins, and primates. Most scholars agree that modern human behavior can be characterize ...
about 160,000–60,000 years ago. The Neolithic Revolution, which began in
Southwest Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...
around 13,000 years ago (and separately in a few other places), saw the emergence of
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...
and permanent
human settlement In geography, statistics and archaeology, a settlement, locality or populated place is a community in which people live. The complexity of a settlement can range from a minuscule number of dwellings grouped together to the largest of ci ...
. As populations became larger and denser, forms of governance developed within and between communities, and a number of
civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). ...
s have risen and fallen. Humans have continued to expand, with a global population of over 8 billion .
Gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s and the environment influence human biological variation in visible characteristics, physiology, disease susceptibility, mental abilities, body size, and life span. Though humans vary in many traits (such as genetic predispositions and physical features), any two humans are at least 99% genetically similar. Humans are sexually dimorphic: generally, males have greater body strength and females have a higher
body fat Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
percentage. At
puberty Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a bo ...
, humans develop
secondary sex characteristic Secondary sex characteristics are features that appear during puberty in humans, and at sexual maturity in other animals. These characteristics are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a s ...
s. Females are capable of
pregnancy Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occur ...
, usually between puberty, at around 12 years, and
menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...
, around the age of 50. Humans are
omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
, capable of consuming a wide variety of plant and animal material, and have used fire and other forms of heat to prepare and
cook Cook or The Cook may refer to: Food preparation * Cooking, the preparation of food * Cook (domestic worker), a household staff member who prepares food * Cook (professional), an individual who prepares food for consumption in the food industry * ...
food since the time of ''H. erectus''. Humans can survive for up to eight weeks without food and three or four days without water. Humans are generally diurnal, sleeping on average seven to nine hours per day.
Childbirth Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births glob ...
is dangerous, with a high risk of complications and death. Often, both the mother and the father provide care for their children, who are helpless at birth. Humans have a large and highly developed
prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46 ...
, the region of the brain associated with higher cognition. They are highly intelligent, capable of
episodic memory Episodic memory is the memory of everyday events (such as times, location geography, associated emotions, and other contextual information) that can be explicitly stated or conjured. It is the collection of past personal experiences that occurred ...
, have flexible facial expressions, self-awareness, and a
theory of mind In psychology, theory of mind refers to the capacity to understand other people by ascribing mental states to them (that is, surmising what is happening in their mind). This includes the knowledge that others' mental states may be different fro ...
. The human mind is capable of
introspection Introspection is the examination of one's own conscious thoughts and feelings. In psychology, the process of introspection relies on the observation of one's mental state, while in a spiritual context it may refer to the examination of one's sou ...
, private thought, imagination, volition, and forming views on
existence Existence is the ability of an entity to interact with reality. In philosophy, it refers to the ontological property of being. Etymology The term ''existence'' comes from Old French ''existence'', from Medieval Latin ''existentia/exsistentia' ...
. This has allowed great technological advancements and complex tool development possible through complex reasoning and the transmission of knowledge to subsequent generations. Language,
art Art is a diverse range of human activity, and resulting product, that involves creative or imaginative talent expressive of technical proficiency, beauty, emotional power, or conceptual ideas. There is no generally agreed definition of wha ...
, and
trade Trade involves the transfer of goods and services from one person or entity to another, often in exchange for money. Economists refer to a system or network that allows trade as a market. An early form of trade, barter, saw the direct excha ...
are defining characteristics of humans. Long-distance trade routes might have led to cultural explosions and resource distribution that gave humans an advantage over other similar species.


Etymology and definition

All modern humans are classified into the
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
''Homo sapiens'', coined by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...
in his 1735 work '' Systema Naturae''. The generic name "''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...
''" is a learned 18th-century derivation from Latin , which refers to humans of either sex. The word ''human'' can refer to all members of the ''Homo'' genus, although in common usage it generally just refers to ''Homo sapiens,'' the only extant species. The name "''Homo'' ''sapiens''" means 'wise man' or 'knowledgeable man'. There is disagreement if certain extinct members of the genus, namely
Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...
s, should be included as a separate species of humans or as a subspecies of ''H. sapiens''. ''Human'' is a
loanword A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because t ...
of
Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English ...
from
Old French Old French (, , ; Modern French: ) was the language spoken in most of the northern half of France from approximately the 8th to the 14th centuries. Rather than a unified language, Old French was a linkage of Romance dialects, mutually intellig ...
, ultimately from
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, the adjectival form of ('man' — in the sense of humankind). The native English term ''
man A man is an adult male human. Prior to adulthood, a male human is referred to as a boy (a male child or adolescent). Like most other male mammals, a man's genome usually inherits an X chromosome from the mother and a Y chromo ...
'' can refer to the species generally (a synonym for ''humanity'') as well as to human males. It may also refer to individuals of either sex, though this form is less common in contemporary English. Despite the fact that the word ''animal'' is colloquially used as an antonym for ''human'', and contrary to a common biological misconception, humans are animals. The word ''
person A person ( : people) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a part of a culturally established form of social relations such as kinship, ownership of prope ...
'' is often used interchangeably with ''human'', but philosophical debate exists as to whether personhood applies to all humans or all sentient beings, and further if one can lose personhood (such as by going into a
persistent vegetative state A persistent vegetative state (PVS) or post-coma unresponsiveness (PCU) is a disorder of consciousness in which patients with severe brain damage are in a state of partial arousal rather than true awareness. After four weeks in a vegetative stat ...
).


Evolution

Humans are apes ( superfamily Hominoidea). The lineage of apes that eventually gave rise to humans first split from gibbons (family Hylobatidae) and
orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...
s (genus ''Pongo''), then
gorilla Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or fi ...
s (genus ''Gorilla''), and finally, chimpanzees and bonobos (genus '' Pan''). The last split, between the human and chimpanzee–bonobo lineages, took place around 8–4 million years ago, in the late
Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
epoch. During this split,
chromosome 2 Chromosome 2 is one of the twenty-three pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 2 is the second-largest human chromosome, spanning more than 242 million base pairs and representing almost e ...
was formed from the joining of two other chromosomes, leaving humans with only 23 pairs of chromosomes, compared to 24 for the other apes. Following their split with chimpanzees and bonobos, the
hominins The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The t ...
diversified into many species and at least two distinct genera. All but one of these lineages—representing the genus ''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...
'' and its sole extant species ''Homo sapiens''—are now extinct. The genus ''Homo'' evolved from ''
Australopithecus ''Australopithecus'' (, ; ) is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genus ''Homo'' (which includes modern humans) emerged within ''Australopithecus'', as sister to e.g. ''Austral ...
''. Though fossils from the transition are scarce, the earliest members of ''Homo'' share several key traits with ''Australopithecus''. The earliest record of ''Homo'' is the 2.8 million-year-old specimen
LD 350-1 LD 350-1 is the earliest known specimen of the genus ''Homo'', dating to 2.8–2.75 million years ago (mya), found in the Ledi-Geraru site in the Afar Region of Ethiopia. The specimen was discovered in silts above the Gurumaha Tuff section of th ...
from Ethiopia, and the earliest named species are '' Homo habilis'' and ''
Homo rudolfensis ''Homo rudolfensis'' is an extinct species of archaic human from the Early Pleistocene of East Africa about 2 million years ago (mya). Because ''H. rudolfensis'' coexisted with several other hominins, it is debated what specimens can be confide ...
'' which evolved by 2.3 million years ago. ''
H. erectus ''Homo erectus'' (; meaning "upright man") is an extinct species of archaic human from the Pleistocene, with its earliest occurrence about 2 million years ago. Several human species, such as '' H. heidelbergensis'' and '' H. antecessor' ...
'' (the African variant is sometimes called '' H. ergaster'') evolved 2 million years ago and was the first
archaic human A number of varieties of '' Homo'' are grouped into the broad category of archaic humans in the period that precedes and is contemporary to the emergence of the earliest early modern humans (''Homo sapiens'') around 300 ka. Omo-Kibish I (Omo I) f ...
species to leave Africa and disperse across Eurasia. ''H. erectus'' also was the first to evolve a characteristically human
body plan A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprin ...
. ''Homo sapiens'' emerged in Africa around 300,000 years ago from a species commonly designated as either '' H. heidelbergensis'' or '' H. rhodesiensis'', the descendants of ''H. erectus'' that remained in Africa. ''H. sapiens'' migrated out of the continent, gradually replacing or interbreeding with local populations of archaic humans. Humans began exhibiting
behavioral modernity Behavioral modernity is a suite of behavioral and cognitive traits that distinguishes current '' Homo sapiens'' from other anatomically modern humans, hominins, and primates. Most scholars agree that modern human behavior can be characterize ...
about 160,000-70,000 years ago, and possibly earlier. The "out of Africa" migration took place in at least two waves, the first around 130,000 to 100,000 years ago, the second (
Southern Dispersal In the context of the recent African origin of modern humans, the Southern Dispersal scenario (also the coastal migration or great coastal migration hypothesis) refers to the early migration along the southern coast of Asia, from the Arabian Pen ...
) around 70,000 to 50,000 years ago. ''H. sapiens'' proceeded to colonize all the continents and larger islands, arriving in
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...
60,000 years ago, Australia around 65,000 years ago, the Americas around 15,000 years ago, and remote islands such as Hawaii,
Easter Island Easter Island ( rap, Rapa Nui; es, Isla de Pascua) is an island and special territory of Chile in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania. The island is most famous for its ne ...
,
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
, and
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
between the years 300 and 1280 CE. Human evolution was not a simple linear or branched progression but involved interbreeding between related species. Genomic research has shown that hybridization between substantially diverged lineages was common in human evolution. DNA evidence suggests that several genes of
Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...
origin are present among all non sub-Saharan African populations, and Neanderthals and other hominins, such as
Denisovan The Denisovans or Denisova hominins ) are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic. Denisovans are known from few physical remains and consequently, most of what is known ...
s, may have contributed up to 6% of their
genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
to present-day non sub-Saharan African humans. Human evolution is characterized by a number of morphological,
developmental Development of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosi ...
, physiological, and
behavioral Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as we ...
changes that have taken place since the split between the last common ancestor of humans and chimpanzees. The most significant of these adaptations are obligate bipedalism, increased brain size and decreased
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
(
neoteny Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compa ...
). The relationship between all these changes is the subject of ongoing debate.


History

Until about 12,000 years ago, all humans lived as hunter-gatherers. The Neolithic Revolution (the invention of
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...
) first took place in
Southwest Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...
and spread through large parts of the Old World over the following millennia. It also occurred independently in
Mesoamerica Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica ...
(about 6,000 years ago), China,
Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...
, and the Sahel and West Savanna regions of Africa. Access to food surplus led to the formation of permanent
human settlement In geography, statistics and archaeology, a settlement, locality or populated place is a community in which people live. The complexity of a settlement can range from a minuscule number of dwellings grouped together to the largest of ci ...
s, the
domestication Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...
of animals and the use of metal tools for the first time in history. Agriculture and sedentary lifestyle led to the emergence of early
civilizations A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). Civi ...
. An urban revolution took place in the
4th millennium BC The 4th millennium BC spanned the years 4000 BC to 3001 BC. Some of the major changes in human culture during this time included the beginning of the Bronze Age and the invention of writing, which played a major role in starting recorded history. ...
E with the development of
city-state A city-state is an independent sovereign city which serves as the center of political, economic, and cultural life over its contiguous territory. They have existed in many parts of the world since the dawn of history, including cities such as ...
s, particularly Sumerian cities located in
Mesopotamia Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
. It was in these cities that the earliest known form of writing, cuneiform script, appeared around 3000 BCE. Other major civilizations to develop around this time were Ancient Egypt and the Indus Valley Civilization. They eventually traded with each other and invented technology such as wheels, plows and sails. Astronomy and mathematics were also developed and the
Great Pyramid of Giza The Great Pyramid of Giza is the biggest Egyptian pyramid and the tomb of Fourth Dynasty pharaoh Khufu. Built in the early 26th century BC during a period of around 27 years, the pyramid is the oldest of the Seven Wonders of the Ancient Worl ...
was built. There is evidence of a severe drought lasting about a hundred years that may have caused the decline of these civilizations, with new ones appearing in the aftermath. Babylonians came to dominate Mesopotamia while others, such as
Poverty Point culture The Poverty Point culture is the archaeological culture of a prehistoric indigenous peoples who inhabited a portion of North America's lower Mississippi Valley and surrounding Gulf coast from about 1730 – 1350 BC. Archeologists have identified ...
s, Minoans and the
Shang dynasty The Shang dynasty (), also known as the Yin dynasty (), was a Chinese royal dynasty founded by Tang of Shang (Cheng Tang) that ruled in the Yellow River valley in the second millennium BC, traditionally succeeding the Xia dynasty and ...
, rose to prominence in new areas. The Bronze Age suddenly collapsed around 1200 BCE, resulting in the disappearance of a number of civilizations and the beginning of the Greek Dark Ages. During this period iron started replacing bronze, leading to the
Iron Age The Iron Age is the final epoch of the three-age division of the prehistory and protohistory of humanity. It was preceded by the Stone Age ( Paleolithic, Mesolithic, Neolithic) and the Bronze Age ( Chalcolithic). The concept has been mostl ...
. In the 5th century BCE, history started being recorded as a discipline, which provided a much clearer picture of life at the time. Between the 8th and 6th century BCE, Europe entered the
classical antiquity Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations of ...
age, a period when
ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
and
ancient Rome In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
flourished. Around this time other civilizations also came to prominence. The
Maya civilization The Maya civilization () of the Mesoamerican people is known by its ancient temples and glyphs. Its Maya script is the most sophisticated and highly developed writing system in the pre-Columbian Americas. It is also noted for its art, a ...
started to build cities and create complex calendars. In Africa, the Kingdom of Aksum overtook the declining
Kingdom of Kush The Kingdom of Kush (; Egyptian: 𓎡𓄿𓈙𓈉 ''kꜣš'', Assyrian: ''Kûsi'', in LXX grc, Κυς and Κυσι ; cop, ''Ecōš''; he, כּוּשׁ ''Kūš'') was an ancient kingdom in Nubia, centered along the Nile Valley in wh ...
and facilitated trade between India and the Mediterranean. In West Asia, the Achaemenid Empire's system of centralized governance became the precursor to many later empires, while the
Gupta Empire The Gupta Empire was an ancient Indian empire which existed from the early 4th century CE to late 6th century CE. At its zenith, from approximately 319 to 467 CE, it covered much of the Indian subcontinent. This period is considered as the Gold ...
in India and the
Han dynasty The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a warr ...
in China have been described as golden ages in their respective regions. Following the
fall of the Western Roman Empire The fall of the Western Roman Empire (also called the fall of the Roman Empire or the fall of Rome) was the loss of central political control in the Western Roman Empire, a process in which the Empire failed to enforce its rule, and its vas ...
in 476, Europe entered the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
. During this period,
Christianity Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion with roughly 2.38 billion followers representing one-third of the global pop ...
and the
Church Church may refer to: Religion * Church (building), a building for Christian religious activities * Church (congregation), a local congregation of a Christian denomination * Church service, a formalized period of Christian communal worship * C ...
would provide centralized authority and education. In the Middle East, Islam became the prominent religion and expanded into North Africa. It led to an
Islamic Golden Age The Islamic Golden Age was a period of cultural, economic, and scientific flourishing in the history of Islam, traditionally dated from the 8th century to the 14th century. This period is traditionally understood to have begun during the reign ...
, inspiring achievements in
architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...
, the revival of old advances in science and technology, and the formation of a distinct way of life. The Christian and Islamic worlds would eventually clash, with the
Kingdom of England The Kingdom of England (, ) was a sovereign state on the island of Great Britain from 12 July 927, when it emerged from various History of Anglo-Saxon England, Anglo-Saxon kingdoms, until 1 May 1707, when it united with Kingdom of Scotland, ...
, the
Kingdom of France The Kingdom of France ( fro, Reaume de France; frm, Royaulme de France; french: link=yes, Royaume de France) is the historiographical name or umbrella term given to various political entities of France in the medieval and early modern period ...
and the
Holy Roman Empire The Holy Roman Empire was a political entity in Western, Central, and Southern Europe that developed during the Early Middle Ages and continued until its dissolution in 1806 during the Napoleonic Wars. From the accession of Otto I in 962 ...
declaring a series of holy wars to regain control of the Holy Land from Muslims. In the Americas, complex Mississippian societies would arise starting around 800 CE, while further south, the Aztecs and
Incas The Inca Empire (also known as the Incan Empire and the Inka Empire), called ''Tawantinsuyu'' by its subjects, ( Quechua for the "Realm of the Four Parts",  "four parts together" ) was the largest empire in pre-Columbian America. The adm ...
would become the dominant powers. The Mongol Empire would conquer much of
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...
in the 13th and 14th centuries. Over this same time period, the Mali Empire in Africa grew to be the largest empire on the continent, stretching from Senegambia to Ivory Coast. Oceania would see the rise of the
Tuʻi Tonga Empire The Tui Tonga Empire, or Tongan Empire, are descriptions sometimes given to Tongan expansionism and projected hegemony in Oceania which began around 950 CE, reaching its peak during the period 1200–1500. It was centred in Tonga on the island o ...
which expanded across many islands in the South Pacific. The early modern period in Europe and the Near East (c.1450–1800) began with the final defeat of the Byzantine Empire, and the
rise of the Ottoman Empire The rise of the Ottoman Empire is a period of history that started with the emergence of the Ottoman principality (Osmanlı Beyliği) in , and ended circa 1453. This period witnessed the foundation of a political entity ruled by the Ottoman D ...
. Meanwhile, Japan entered the
Edo period The or is the period between 1603 and 1867 in the history of Japan, when Japan was under the rule of the Tokugawa shogunate and the country's 300 regional '' daimyo''. Emerging from the chaos of the Sengoku period, the Edo period was characte ...
, the
Qing dynasty The Qing dynasty ( ), officially the Great Qing,, was a Manchu-led imperial dynasty of China and the last orthodox dynasty in Chinese history. It emerged from the Later Jin dynasty founded by the Jianzhou Jurchens, a Tungusic-spea ...
rose in China and the
Mughal Empire The Mughal Empire was an early-modern empire that controlled much of South Asia between the 16th and 19th centuries. Quote: "Although the first two Timurid emperors and many of their noblemen were recent migrants to the subcontinent, the d ...
ruled much of India. Europe underwent the
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...
, starting in the 15th century, and the
Age of Discovery The Age of Discovery (or the Age of Exploration), also known as the early modern period, was a period largely overlapping with the Age of Sail, approximately from the 15th century to the 17th century in European history, during which seafarin ...
began with the exploring and colonizing of new regions. This includes the
British Empire The British Empire was composed of the dominions, colonies, protectorates, mandates, and other territories ruled or administered by the United Kingdom and its predecessor states. It began with the overseas possessions and trading posts e ...
expanding to become the world's largest empire and the colonization of the Americas. This expansion led to the Atlantic slave trade and the genocide of Native American peoples. This period also marked the
Scientific Revolution The Scientific Revolution was a series of events that marked the emergence of modern science during the early modern period, when developments in mathematics, physics, astronomy, biology (including human anatomy) and chemistry transfo ...
, with great advances in mathematics,
mechanics Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to object ...
,
astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
and
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
. The late modern period (1800–present) saw the
Technological Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, ...
and
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
bring such discoveries as imaging technology, major innovations in transport and energy development. The
United States of America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
underwent great change, going from a small group of colonies to one of the global superpowers. The
Napoleonic Wars The Napoleonic Wars (1803–1815) were a series of major global conflicts pitting the French Empire and its allies, led by Napoleon I, against a fluctuating array of European states formed into various coalitions. It produced a period of Fren ...
raged through Europe in the early 1800s, Spain lost most of its colonies in the
New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...
, while Europeans continued expansion into Africa—where European control went from 10% to almost 90% in less than 50 years—and Oceania. A tenuous balance of power among European nations collapsed in 1914 with the outbreak of the
First World War World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, one of the deadliest conflicts in history. In the 1930s, a worldwide economic crisis led to the rise of authoritarian regimes and a
Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...
, involving almost all of the world's countries. Following its conclusion in 1945, the Cold War between the
USSR The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
and the United States saw a struggle for global influence, including a
nuclear arms race The nuclear arms race was an arms race competition for supremacy in nuclear warfare between the United States, the Soviet Union, and their respective allies during the Cold War. During this same period, in addition to the American and Soviet nuc ...
and a
space race The Space Race was a 20th-century competition between two Cold War rivals, the United States and the Soviet Union, to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the t ...
. The current
Information Age The Information Age (also known as the Computer Age, Digital Age, Silicon Age, or New Media Age) is a historical period that began in the mid-20th century. It is characterized by a rapid shift from traditional industries, as established during ...
sees the world becoming increasingly
globalized Globalization, or globalisation (Commonwealth English; see spelling differences), is the process of interaction and integration among people, companies, and governments worldwide. The term ''globalization'' first appeared in the early 20t ...
and interconnected.


Habitat and population

Early human settlements were dependent on proximity to
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
and—depending on the lifestyle—other
natural resource Natural resources are resources that are drawn from nature and used with few modifications. This includes the sources of valued characteristics such as commercial and industrial use, aesthetic value, scientific interest and cultural value. ...
s used for
subsistence A subsistence economy is an economy directed to basic subsistence (the provision of food, clothing, shelter) rather than to the market. Henceforth, "subsistence" is understood as supporting oneself at a minimum level. Often, the subsistence econo ...
, such as populations of animal prey for
hunting Hunting is the human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products ( fur/ hide, bone/tusks, horn/antler, ...
and
arable land Arable land (from the la, arabilis, "able to be ploughed") is any land capable of being ploughed and used to grow crops.''Oxford English Dictionary'', "arable, ''adj''. and ''n.''" Oxford University Press (Oxford), 2013. Alternatively, for th ...
for growing crops and grazing livestock. Modern humans, however, have a great capacity for altering their habitats by means of technology,
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...
,
urban planning Urban planning, also known as town planning, city planning, regional planning, or rural planning, is a technical and political process that is focused on the development and design of land use and the built environment, including air, water, ...
, construction,
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
and desertification.
Human settlements In geography, statistics and archaeology, a settlement, locality or populated place is a community in which people live. The complexity of a settlement can range from a minuscule number of dwellings grouped together to the largest of cities ...
continue to be vulnerable to natural disasters, especially those placed in hazardous locations and with low quality of construction. Grouping and deliberate habitat alteration is often done with the goals of providing protection, accumulating comforts or material wealth, expanding the available food, improving
aesthetics Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed t ...
, increasing knowledge or enhancing the exchange of resources. Humans are one of the most adaptable species, despite having a low or narrow tolerance for many of the earth's extreme environments. Through advanced tools, humans have been able to extend their tolerance to a wide variety of temperatures,
humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...
, and altitudes. As a result, humans are a cosmopolitan species found in almost all regions of the world, including
tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equa ...
, arid desert, extremely cold
arctic region The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenland), Finland, Iceland, N ...
s, and heavily polluted cities; in comparison, most other species are confined to a few geographical areas by their limited adaptability. The human population is not, however, uniformly distributed on the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's surface, because the population density varies from one region to another, and large stretches of surface are almost completely uninhabited, like
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
and vast swathes of the ocean. Most humans (61%) live in Asia; the remainder live in the Americas (14%), Africa (14%), Europe (11%), and Oceania (0.5%). Within the last century, humans have explored challenging environments such as Antarctica, the
deep sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...
, and
outer space Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
. Human habitation within these hostile environments is restrictive and expensive, typically limited in duration, and restricted to
scientific Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...
,
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...
, or industrial expeditions. Humans have briefly visited the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
and made their presence felt on other celestial bodies through human-made robotic spacecraft. Since the early 20th century, there has been continuous human presence in Antarctica through
research stations Research stations are facilities where scientific investigation, collection, analysis and experimentation occurs. A research station is a facility that is built for the purpose of conducting scientific research. There are also many types of resea ...
and, since 2000,
in space ''In Space'' is the fourth and final studio album by American rock group Big Star, released in 2005. It was the first new studio recording by the band since '' Third/Sister Lovers'', which was recorded in 1974. The album featured original Big ...
through habitation on the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ( ...
. Estimates of the population at the time agriculture emerged in around 10,000 BC have ranged between 1 million and 15 million. Around 50–60 million people lived in the combined eastern and western
Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediter ...
in the 4th century AD. Bubonic plagues, first recorded in the 6th century AD, reduced the population by 50%, with the Black Death killing 75–200 million people in
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...
and
North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...
alone. Human population was believed to have reached one billion in 1800. It has since then increased exponentially, reaching two billion in 1930 and three billion in 1960, four in 1975, five in 1987 and six billion in 1999. It passed seven billion in 2011 and was expected to pass eight billion in November 2022. It took over two million years of
human prehistory Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of ...
and
history History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the invention of writing systems is considered prehistory. "History" is an umbrella term comprising past events as well ...
for the human population to reach one
billion Billion is a word for a large number, and it has two distinct definitions: *1,000,000,000, i.e. one thousand million, or (ten to the ninth power), as defined on the short scale. This is its only current meaning in English. * 1,000,000,000,000, i. ...
and only 207 years more to grow to 7 billion. The combined biomass of the carbon of all the humans on Earth in 2018 was estimated at 60 million tons, about 10 times larger than that of all non-domesticated mammals. In 2018, 4.2 billion humans (55%) lived in urban areas, up from 751 million in 1950. The most urbanized regions are Northern America (82%), Latin America (81%), Europe (74%) and Oceania (68%), with Africa and Asia having nearly 90% of the world's 3.4 billion rural population. Problems for humans living in cities include various forms of pollution and crime, especially in inner city and suburban slums. Humans have had a dramatic effect on the environment. They are
apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
s, being rarely preyed upon by other species. Human population growth, industrialization, land development,
overconsumption Overconsumption describes a situation where a consumer overuses their available goods and services to where they can't, or don't want to, replenish or reuse them. In microeconomics, this may be described as the point where the marginal cost of ...
and combustion of fossil fuels have led to
environmental destruction Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defined ...
and
pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
that significantly contributes to the ongoing
mass extinction An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
of other forms of life. They are the main contributor to global
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
, which may accelerate the Holocene extinction.


Biology


Anatomy and physiology

Most aspects of human physiology are closely homologous to corresponding aspects of animal physiology. The human body consists of the legs, the
torso The torso or trunk is an anatomical term for the central part, or the core, of the body of many animals (including humans), from which the head, neck, limbs, tail and other appendages extend. The tetrapod torso — including that of a huma ...
, the arms, the neck, and the head. An adult human body consists of about 100 trillion (1014) cells. The most commonly defined body systems in humans are the nervous, the
cardiovascular The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
, the digestive, the endocrine, the
immune In biology, immunity is the capability of multicellular organisms to resist harmful microorganisms. Immunity involves both specific and nonspecific components. The nonspecific components act as barriers or eliminators of a wide range of pathogens ...
, the
integumentary The integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the skin and its appendages, which act as a physical barrier between the external environment and the internal environment that it serves ...
, the
lymphatic Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to ...
, the
musculoskeletal The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system prov ...
, the reproductive, the
respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gre ...
, and the
urinary system The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, c ...
. The
dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolog ...
of humans is: . Humans have proportionately shorter
palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separ ...
s and much smaller
teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...
than other primates. They are the only primates to have short, relatively flush
canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...
. Humans have characteristically crowded teeth, with gaps from lost teeth usually closing up quickly in young individuals. Humans are gradually losing their third molars, with some individuals having them congenitally absent. Humans share with chimpanzees a
vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
tail, appendix, flexible shoulder joints, grasping fingers and
opposable thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...
s. Apart from bipedalism and brain size, humans differ from chimpanzees mostly in smelling,
hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is audit ...
and digesting proteins. While humans have a density of hair follicles comparable to other apes, it is predominantly
vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair that develops on most of a human’s body during childhood. Exceptions include the lips, the back of the ear, the palm of the hand, the sole of the foot, some external genital ...
, most of which is so short and wispy as to be practically invisible. Humans have about 2 million sweat glands spread over their entire bodies, many more than chimpanzees, whose sweat glands are scarce and are mainly located on the palm of the hand and on the soles of the feet. It is estimated that the worldwide average height for an adult human male is about , while the worldwide average height for adult human females is about . Shrinkage of stature may begin in middle age in some individuals but tends to be typical in the extremely
aged Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...
. Throughout history, human populations have universally become taller, probably as a consequence of better nutrition, healthcare, and living conditions. The average
mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...
of an adult human is for females and for males. Like many other conditions, body weight and body type are influenced by both genetic susceptibility and environment and varies greatly among individuals. Humans have a far faster and more accurate
throw Throwing is an action which consists in accelerating a projectile and then releasing it so that it follows a ballistic trajectory, usually with the aim of impacting a remote target. This action is best characterized for animals with prehensil ...
than other animals. Humans are also among the best long-distance runners in the animal kingdom, but slower over short distances. Humans' thinner body hair and more productive sweat glands help avoid
heat exhaustion Heat exhaustion is a severe form of heat illness. It is a medical emergency. Heat exhaustion is caused by the loss of water and electrolytes through sweating. The United States Department of Labor makes the following recommendation, "Heat illness ...
while running for long distances.


Genetics

Like most animals, humans are a diploid and
eukaryotic Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the ...
species. Each somatic cell has two sets of 23
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s, each set received from one parent;
gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
s have only one set of chromosomes, which is a mixture of the two parental sets. Among the 23 pairs of chromosomes, there are 22 pairs of autosomes and one pair of
sex chromosomes A sex chromosome (also referred to as an allosome, heterotypical chromosome, gonosome, heterochromosome, or idiochromosome) is a chromosome that differs from an ordinary autosome in form, size, and behavior. The human sex chromosomes, a typical ...
. Like other mammals, humans have an
XY sex-determination system The XY sex-determination system is a sex-determination system used to classify many mammals, including humans, some insects (''Drosophila''), some snakes, some fish ( guppies), and some plants ('' Ginkgo'' tree). In this system, the sex of an i ...
, so that females have the sex chromosomes XX and males have XY.
Gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s and environment influence human biological variation in visible characteristics, physiology, disease susceptibility and mental abilities. The exact influence of genes and environment on certain traits is not well understood. While no humans—not even
monozygotic twins Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
—are genetically identical, two humans on average will have a genetic similarity of 99.5%-99.9%. This makes them more homogeneous than other great apes, including chimpanzees. This small variation in human DNA compared to many other species suggests a population bottleneck during the Late Pleistocene (around 100,000 years ago), in which the human population was reduced to a small number of breeding pairs. The forces of
natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Cha ...
have continued to operate on human populations, with evidence that certain regions of the
genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
display
directional selection In population genetics, directional selection, is a mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. Under dir ...
in the past 15,000 years. The
human genome The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the ...
was first sequenced in 2001 and by 2020 hundreds of thousands of genomes had been sequenced. In 2012 the
International HapMap Project The International HapMap Project was an organization that aimed to develop a haplotype map (HapMap) of the human genome, to describe the common patterns of human genetic variation. HapMap is used to find genetic variants affecting health, disease ...
had compared the genomes of 1,184 individuals from 11 populations and identified 1.6 million single nucleotide polymorphisms. African populations harbor the highest number of private genetic variants. While many of the common variants found in populations outside of Africa are also found on the African continent, there are still large numbers that are private to these regions, especially
Oceania Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...
and
the Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...
. By 2010 estimates, humans have approximately 22,000 genes. By comparing mitochondrial DNA, which is inherited only from the mother, geneticists have concluded that the last female common ancestor whose
genetic marker A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be ...
is found in all modern humans, the so-called
mitochondrial Eve In human genetics, the Mitochondrial Eve (also ''mt-Eve, mt-MRCA'') is the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an ...
, must have lived around 90,000 to 200,000 years ago.


Life cycle

Most
human reproduction Human reproduction is sexual reproduction that results in human fertilization to produce a human offspring. It typically involves sexual intercourse between a sexually mature human male and female. During sexual intercourse, the interaction ...
takes place by
internal fertilization Internal fertilization is the union of an egg and sperm cell during sexual reproduction inside the female body. Internal fertilization, unlike its counterpart, external fertilization, brings more control to the female with reproduction. For inte ...
via sexual intercourse, but can also occur through assisted reproductive technology procedures. The average gestation period is 38 weeks, but a normal pregnancy can vary by up to 37 days. Embryonic development in the human covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a
fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...
. Humans are able to induce early labor or perform a caesarean section if the child needs to be born earlier for medical reasons. In developed countries, infants are typically in weight and in height at birth. However,
low birth weight Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal inten ...
is common in developing countries, and contributes to the high levels of infant mortality in these regions. Compared with other species, human childbirth is dangerous, with a much higher risk of complications and death. The size of the fetus's head is more closely matched to the pelvis than other primates. The reason for this is not completely understood, but it contributes to a painful labor that can last 24 hours or more. The chances of a successful labor increased significantly during the 20th century in wealthier countries with the advent of new medical technologies. In contrast, pregnancy and
natural childbirth Natural childbirth is childbirth without routine medical interventions, particularly anesthesia. Natural childbirth arose in opposition to the techno-medical model of childbirth that has recently gained popularity in industrialized societies. Natur ...
remain hazardous ordeals in developing regions of the world, with maternal death rates approximately 100 times greater than in developed countries. Both the mother and the father provide care for human offspring, in contrast to other primates, where parental care is mostly done by the mother. Helpless at birth, humans continue to grow for some years, typically reaching
sexual maturity Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definit ...
at 15 to 17 years of age. The human life span has been split into various stages ranging from three to twelve. Common stages include infancy,
childhood A child (plural, : children) is a human being between the stages of childbirth, birth and puberty, or between the Development of the human body, developmental period of infancy and puberty. The legal definition of ''child'' generally refers ...
, adolescence, adulthood and old age. The lengths of these stages have varied across cultures and time periods but is typified by an unusually rapid growth spurt during adolescence. Human females undergo
menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...
and become infertile at around the age of 50. It has been proposed that menopause increases a woman's overall reproductive success by allowing her to invest more time and resources in her existing offspring, and in turn their children (the grandmother hypothesis), rather than by continuing to bear children into old age. The life span of an individual depends on two major factors, genetics and lifestyle choices. For various reasons, including biological/genetic causes, women live on average about four years longer than men. , the global average
life expectancy at birth Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy t ...
of a girl is estimated to be 74.9 years compared to 70.4 for a boy. There are significant geographical variations in human life expectancy, mostly correlated with economic development—for example, life expectancy at birth in Hong Kong is 87.6 years for girls and 81.8 for boys, while in the
Central African Republic The Central African Republic (CAR; ; , RCA; , or , ) is a landlocked country in Central Africa. It is bordered by Chad to the north, Sudan to the northeast, South Sudan to the southeast, the DR Congo to the south, the Republic of th ...
, it is 55.0 years for girls and 50.6 for boys. The developed world is generally aging, with the median age around 40 years. In the developing world, the median age is between 15 and 20 years. While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older. In 2012, the United Nations estimated that there were 316,600 living
centenarians A centenarian is a person who has reached the age of 100 years. Because life expectancies worldwide are below 100 years, the term is invariably associated with longevity. In 2012, the United Nations estimated that there were 316,600 living centen ...
(humans of age 100 or older) worldwide.


Diet

Humans are
omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
, capable of consuming a wide variety of plant and animal material. Human groups have adopted a range of diets from purely
vegan Veganism is the practice of abstaining from the use of animal product—particularly in diet—and an associated philosophy that rejects the commodity status of animals. An individual who follows the diet or philosophy is known as a vegan. ...
to primarily carnivorous. In some cases, dietary restrictions in humans can lead to deficiency diseases; however, stable human groups have adapted to many dietary patterns through both genetic specialization and cultural conventions to use nutritionally balanced food sources. The human diet is prominently reflected in human culture and has led to the development of
food science Food science is the basic science and applied science of food; its scope starts at overlap with agricultural science and nutritional science and leads through the scientific aspects of food safety and food processing, informing the development ...
. Until the development of agriculture approximately 10,000 years ago, ''Homo sapiens'' employed a hunter-gatherer method as their sole means of food collection. This involved combining stationary food sources (such as fruits, grains, tubers, and mushrooms, insect larvae and aquatic mollusks) with
wild game Game or quarry is any wild animal hunted for animal products (primarily meat), for recreation (" sporting"), or for trophies. The species of animals hunted as game varies in different parts of the world and by different local jurisdictions, th ...
, which must be hunted and captured in order to be consumed. It has been proposed that humans have used fire to prepare and
cook Cook or The Cook may refer to: Food preparation * Cooking, the preparation of food * Cook (domestic worker), a household staff member who prepares food * Cook (professional), an individual who prepares food for consumption in the food industry * ...
food since the time of '' Homo erectus''. Around ten thousand years ago, humans developed agriculture, which substantially altered their diet. This change in diet may also have altered human biology; with the spread of
dairy farming Dairy farming is a class of agriculture for long-term production of milk, which is processed (either on the farm or at a dairy plant, either of which may be called a dairy) for eventual sale of a dairy product. Dairy farming has a history th ...
providing a new and rich source of food, leading to the evolution of the ability to digest lactose in some adults. The types of food consumed, and how they are prepared, have varied widely by time, location, and culture. In general, humans can survive for up to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days, with a maximum of one week. In 2020 it is estimated 9 million humans die every year from causes directly or indirectly related to starvation. Childhood malnutrition is also common and contributes to the global burden of disease. However, global food distribution is not even, and
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...
among some human populations has increased rapidly, leading to health complications and increased mortality in some developed and a few
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
. Worldwide, over one billion people are obese, while in the United States 35% of people are obese, leading to this being described as an "
obesity epidemic Obesity has been observed throughout human history. Many early depictions of the human form in art and sculpture appear obese. However, it was not until the 20th century that obesity became common — so much so that, in 1997, the World Heal ...
." Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by an energy-dense diet.


Biological variation

There is biological variation in the human species—with traits such as blood type,
genetic diseases A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...
, cranial features, facial features,
organ systems An organ system is a biological system consisting of a group of organs that work together to perform one or more functions. Each organ has a specialized role in a plant or animal body, and is made up of distinct tissues. Plants Plants have ...
,
eye color Eye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. In humans, the ...
,
hair color Human hair color is the pigmentation of human hair follicles due to two types of melanin: eumelanin and pheomelanin. Generally, if more melanin is present, the color of the hair is darker; if less melanin is present, the hair is lighter. The t ...
and
texture Texture may refer to: Science and technology * Surface texture, the texture means smoothness, roughness, or bumpiness of the surface of an object * Texture (roads), road surface characteristics with waves shorter than road roughness * Texture ...
,
height Height is measure of vertical distance, either vertical extent (how "tall" something or someone is) or vertical position (how "high" a point is). For example, "The height of that building is 50 m" or "The height of an airplane in-flight is ab ...
and build, and
skin color Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigmentation, which is the result of genetics (inherited from one's biological parents and or individu ...
varying across the globe. The typical height of an adult human is between , although this varies significantly depending on sex,
ethnic origin An ethnic group or an ethnicity is a grouping of people who identify with each other on the basis of shared attributes that distinguish them from other groups. Those attributes can include common sets of traditions, ancestry, language, history, ...
, and family bloodlines. Body size is partly determined by genes and is also significantly influenced by environmental factors such as
diet Diet may refer to: Food * Diet (nutrition), the sum of the food consumed by an organism or group * Dieting, the deliberate selection of food to control body weight or nutrient intake ** Diet food, foods that aid in creating a diet for weight loss ...
, exercise, and sleep patterns. There is evidence that populations have adapted genetically to various external factors. The genes that allow adult humans to digest lactose are present in high frequencies in populations that have long histories of cattle domestication and are more dependent on
cow milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modulati ...
.
Sickle cell anemia Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red bl ...
, which may provide increased resistance to
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
, is frequent in populations where
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
is endemic. Populations that have for a very long time inhabited specific climates tend to have developed specific
phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...
s that are beneficial for those environments— short stature and stocky build in cold regions, tall and lanky in hot regions, and with high lung capacities or other adaptations at high altitudes. Some populations have evolved highly unique adaptations to very specific environmental conditions, such as those advantageous to ocean-dwelling lifestyles and
freediving Freediving, free-diving, free diving, breath-hold diving, or skin diving is a form of underwater diving that relies on breath-holding until resurfacing rather than the use of breathing apparatus such as scuba gear. Besides the limits of breath-h ...
in the
Bajau The Sama-Bajau include several Austronesian ethnic groups of Maritime Southeast Asia. The name collectively refers to related people who usually call themselves the Sama or Samah (formally A'a Sama, "Sama people"); or are known by the exonym ...
. Human hair ranges in color from
red Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
to blond to
brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model us ...
to
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ...
, which is the most frequent. Hair color depends on the amount of
melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
, with concentrations fading with increased age, leading to
grey Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...
or even white hair. Skin color can range from darkest brown to lightest peach, or even nearly white or colorless in cases of
albinism Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the term ...
. It tends to vary clinally and generally correlates with the level of ultraviolet radiation in a particular geographic area, with darker skin mostly around the equator. Skin darkening may have evolved as protection against ultraviolet solar radiation. Light skin pigmentation protects against depletion of
vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (c ...
, which requires sunlight to make. Human skin also has a capacity to darken (tan) in response to exposure to ultraviolet radiation. There is relatively little variation between human geographical populations, and most of the variation that occurs is at the individual level. Much of human variation is continuous, often with no clear points of demarcation. Genetic data shows that no matter how population groups are defined, two people from the same population group are almost as different from each other as two people from any two different population groups. Dark-skinned populations that are found in Africa, Australia, and South Asia are not closely related to each other. Genetic research has demonstrated that human populations native to the African continent are the most genetically diverse and genetic diversity decreases with migratory distance from Africa, possibly the result of bottlenecks during human migration. These non-African populations acquired new genetic inputs from local admixture with archaic populations and have much greater variation from Neanderthals and Denisovans than is found in Africa, though Neanderthal admixture into African populations may be underestimated. Furthermore, recent studies have found that populations in sub-Saharan Africa, and particularly
West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, M ...
, have ancestral genetic variation which predates modern humans and has been lost in most non-African populations. Some of this ancestry is thought to originate from admixture with an unknown archaic hominin that diverged before the split of Neanderthals and modern humans. Humans are a
gonochoric In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism c ...
species, meaning they are divided into male and female
sex Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones ( ova, of ...
es. The greatest degree of genetic variation exists between males and females. While the
nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecule ...
genetic variation of individuals of the same sex across global populations is no greater than 0.1%–0.5%, the genetic difference between
males Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot reproduce sexually without access to ...
and
females Female (symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Females ...
is between 1% and 2%. Males on average are 15% heavier and taller than females. On average, men have about 40–50% more upper body strength and 20–30% more lower body strength than women at the same weight, due to higher amounts of muscle and larger muscle fibers. Women generally have a higher
body fat Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
percentage than men. Women have lighter skin than men of the same population; this has been explained by a higher need for vitamin D in females during pregnancy and
lactation Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The proces ...
. As there are chromosomal differences between females and males, some X and Y chromosome-related conditions and disorders only affect either men or women. After allowing for body weight and volume, the male voice is usually an octave deeper than the female voice. Women have a longer life span in almost every population around the world.


Psychology

The
human brain The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the act ...
, the focal point of the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
in humans, controls the
peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brain ...
. In addition to controlling "lower," involuntary, or primarily autonomic activities such as
respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...
and
digestion Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...
, it is also the locus of "higher" order functioning such as thought,
reason Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
ing, and abstraction. These
cognitive processes Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
constitute the mind, and, along with their behavioral consequences, are studied in the field of
psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...
. Humans have a larger and more developed
prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46 ...
than other primates, the region of the brain associated with higher cognition. This has led humans to proclaim themselves to be more intelligent than any other known species. Objectively defining intelligence is difficult, with other animals adapting senses and excelling in areas that humans are unable to. There are some traits that, although not strictly unique, do set humans apart from other animals. Humans may be the only animals who have
episodic memory Episodic memory is the memory of everyday events (such as times, location geography, associated emotions, and other contextual information) that can be explicitly stated or conjured. It is the collection of past personal experiences that occurred ...
and who can engage in "
mental time travel In psychology, mental time travel is the capacity to mentally reconstruct personal events from the past (episodic memory) as well as to imagine possible scenarios in the future (episodic foresight / episodic future thinking). The term was coine ...
". Even compared with other social animals, humans have an unusually high degree of flexibility in their facial expressions. Humans are the only animals known to cry emotional tears. Humans are one of the few animals able to self-recognize in
mirror test The mirror test—sometimes called the mark test, mirror self-recognition (MSR) test, red spot technique, or rouge test—is a behavioral technique developed in 1970 by American psychologist Gordon Gallup Jr. as an attempt to determine whether an ...
s and there is also debate over to what extent humans are the only animals with a
theory of mind In psychology, theory of mind refers to the capacity to understand other people by ascribing mental states to them (that is, surmising what is happening in their mind). This includes the knowledge that others' mental states may be different fro ...
.


Sleep and dreaming

Humans are generally diurnal. The average sleep requirement is between seven and nine hours per day for an adult and nine to ten hours per day for a child; elderly people usually sleep for six to seven hours. Having less sleep than this is common among humans, even though sleep deprivation can have negative health effects. A sustained restriction of adult sleep to four hours per day has been shown to correlate with changes in physiology and mental state, including reduced memory, fatigue, aggression, and bodily discomfort. During sleep humans dream, where they experience sensory images and sounds. Dreaming is stimulated by the
pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of Va ...
and mostly occurs during the REM phase of sleep. The length of a dream can vary, from a few seconds up to 30 minutes. Humans have three to five dreams per night, and some may have up to seven; however most dreams are immediately or quickly forgotten. They are more likely to remember the dream if awakened during the REM phase. The events in dreams are generally outside the control of the dreamer, with the exception of
lucid dream A lucid dream is a type of dream in which the dreamer becomes aware that they are dreaming while dreaming. During a lucid dream, the dreamer may gain some amount of control over the dream characters, narrative, or environment; however, this is ...
ing, where the dreamer is
self-aware In philosophy of self, self-awareness is the experience of one's own personality or individuality. It is not to be confused with consciousness in the sense of qualia. While consciousness is being aware of one's environment and body and lifest ...
. Dreams can at times make a creative thought occur or give a sense of inspiration.


Consciousness and thought

Human consciousness, at its simplest, is sentience or
awareness Awareness is the state of being conscious of something. More specifically, it is the ability to directly know and perceive, to feel, or to be cognizant of events. Another definition describes it as a state wherein a subject is aware of some infor ...
of internal or external existence. Despite centuries of analyses, definitions, explanations and debates by philosophers and scientists, consciousness remains puzzling and controversial, being "at once the most familiar and most mysterious aspect of our lives". The only widely agreed notion about the topic is the intuition that it exists. Opinions differ about what exactly needs to be studied and explained as consciousness. Some philosophers divide consciousness into phenomenal consciousness, which is sensory experience itself, and access consciousness, which can be used for reasoning or directly controlling actions. It is sometimes synonymous with 'the mind', and at other times, an aspect of it. Historically it is associated with
introspection Introspection is the examination of one's own conscious thoughts and feelings. In psychology, the process of introspection relies on the observation of one's mental state, while in a spiritual context it may refer to the examination of one's sou ...
, private thought, imagination and volition. It now often includes some kind of
experience Experience refers to conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these conscious processes. Understood as a conscious event in the widest sense, experience involv ...
, cognition, feeling or
perception Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...
. It may be 'awareness', or ' awareness of awareness', or self-awareness. There might be different levels or orders of consciousness, or different kinds of consciousness, or just one kind with different features. The process of acquiring knowledge and understanding through thought, experience, and the senses is known as cognition. The human brain perceives the external world through the
sense A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system re ...
s, and each individual human is influenced greatly by his or her experiences, leading to subjective views of
existence Existence is the ability of an entity to interact with reality. In philosophy, it refers to the ontological property of being. Etymology The term ''existence'' comes from Old French ''existence'', from Medieval Latin ''existentia/exsistentia' ...
and the passage of time. The nature of thought is central to psychology and related fields. Cognitive psychology studies cognition, the
mental processes Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
underlying behavior. Largely focusing on the development of the human mind through the life span, developmental psychology seeks to understand how people come to perceive, understand, and act within the world and how these processes change as they age. This may focus on intellectual, cognitive, neural, social, or
moral development Moral Development focuses on the emergence, change and understanding of morality from infancy through adulthood. Morality develops across a life span in a variety of ways and is influenced by an individual's experiences and behavior when faced ...
.
Psychologists A psychologist is a professional who practices psychology and studies mental states, perceptual, cognitive, emotional, and social processes and behavior. Their work often involves the experimentation, observation, and interpretation of how indi ...
have developed intelligence tests and the concept of
intelligence quotient An intelligence quotient (IQ) is a total score derived from a set of standardized tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term ''Intelligen ...
in order to assess the relative intelligence of human beings and study its distribution among population.


Motivation and emotion

Human motivation is not yet wholly understood. From a psychological perspective, Maslow's hierarchy of needs is a well-established theory that can be defined as the process of satisfying certain needs in ascending order of complexity. From a more general, philosophical perspective, human motivation can be defined as a commitment to, or withdrawal from, various goals requiring the application of human ability. Furthermore,
incentive In general, incentives are anything that persuade a person to alter their behaviour. It is emphasised that incentives matter by the basic law of economists and the laws of behaviour, which state that higher incentives amount to greater levels of ...
and preference are both factors, as are any perceived links between incentives and preferences. Volition may also be involved, in which case willpower is also a factor. Ideally, both motivation and volition ensure the selection, striving for, and realization of goals in an optimal manner, a
function Function or functionality may refer to: Computing * Function key, a type of key on computer keyboards * Function model, a structured representation of processes in a system * Function object or functor or functionoid, a concept of object-oriente ...
beginning in childhood and continuing throughout a lifetime in a process known as
socialization In sociology, socialization or socialisation (see spelling differences) is the process of internalizing the norms and ideologies of society. Socialization encompasses both learning and teaching and is thus "the means by which social and cul ...
. Emotions are biological states associated with the nervous system brought on by neurophysiological changes variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or displeasure. They are often intertwined with mood,
temperament In psychology, temperament broadly refers to consistent individual differences in behavior that are biologically based and are relatively independent of learning, system of values and attitudes. Some researchers point to association of temperam ...
,
personality Personality is the characteristic sets of behaviors, cognitions, and emotional patterns that are formed from biological and environmental factors, and which change over time. While there is no generally agreed-upon definition of personality, m ...
, disposition,
creativity Creativity is a phenomenon whereby something new and valuable is formed. The created item may be intangible (such as an idea, a scientific theory, a musical composition, or a joke) or a physical object (such as an invention, a printed Literature ...
, and motivation. Emotion has a significant influence on human behavior and their ability to learn. Acting on extreme or uncontrolled emotions can lead to social disorder and crime, with studies showing criminals may have a lower
emotional intelligence Emotional intelligence (EI) is most often defined as the ability to perceive, use, understand, manage, and handle emotions. People with high emotional intelligence can emotion recognition, recognize their own emotions and those of others, use em ...
than normal. Emotional experiences perceived as pleasant, such as
joy The word joy refers to the emotion evoked by well-being, success, or good fortune, and is typically associated with feelings of intense, long lasting happiness. Dictionary definitions Dictionary definitions of joy typically include a sense of ...
,
interest In finance and economics, interest is payment from a borrower or deposit-taking financial institution to a lender or depositor of an amount above repayment of the principal sum (that is, the amount borrowed), at a particular rate. It is distin ...
or
contentment Contentment is an emotional state of satisfaction that can be seen as a mental state drawn from being at ease in one's situation, body and mind. Colloquially speaking, contentment could be a state of having accepted one's situation and is a m ...
, contrast with those perceived as unpleasant, like
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
,
sadness Sadness is an emotional pain associated with, or characterized by, feelings of disadvantage, loss, despair, grief, helplessness, disappointment and sorrow. An individual experiencing sadness may become quiet or lethargic, and withdraw them ...
,
anger Anger, also known as wrath or rage, is an intense emotional state involving a strong uncomfortable and non-cooperative response to a perceived provocation, hurt or threat. A person experiencing anger will often experience physical effects, su ...
, and despair.
Happiness Happiness, in the context of mental or emotional states, is positive or pleasant emotions ranging from contentment to intense joy. Other forms include life satisfaction, well-being, subjective well-being, flourishing and eudaimonia. ...
, or the state of being happy, is a human emotional condition. The definition of happiness is a common philosophical topic. Some define it as experiencing the feeling of positive emotional affects, while avoiding the negative ones. Others see it as an appraisal of
life satisfaction Life satisfaction is a measure of a person's well-being, assessed in terms of mood, relationship satisfaction, achieved goals, self-concepts, and self-perceived ability to cope with life. Life satisfaction involves a favorable attitude towards one ...
or
quality of life Quality of life (QOL) is defined by the World Health Organization as "an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards ...
. Recent research suggests that being happy might involve experiencing some negative emotions when humans feel they are warranted.


Sexuality and love

For humans, sexuality involves biological, erotic, physical, emotional,
social Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not. Etymology The word "social" derives from ...
, or spiritual feelings and behaviors. Because it is a broad term, which has varied with historical contexts over time, it lacks a precise definition. The biological and physical aspects of sexuality largely concern the human reproductive functions, including the
human sexual response cycle The human sexual response cycle is a four-stage model of physiological responses to sexual stimulation, which, in order of their occurrence, are the excitement, plateau, orgasmic, and resolution phases. This physiological response model was fir ...
. Sexuality also affects and is affected by cultural, political, legal, philosophical, moral,
ethical Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concerns ma ...
, and religious aspects of life. Sexual desire, or ''
libido Libido (; colloquial: sex drive) is a person's overall sexual drive or desire for sexual activity. Libido is influenced by biological, psychological, and social factors. Biologically, the sex hormones and associated neurotransmitters that act u ...
'', is a basic mental state present at the beginning of sexual behavior. Studies show that men desire sex more than women and
masturbate Masturbation is the sexual stimulation of one's own genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. The stimulation may involve hands, fingers, everyday objects, sex toys such as vibrators, or combination ...
more often. Humans can fall anywhere along a continuous scale of
sexual orientation Sexual orientation is an enduring pattern of romantic or sexual attraction (or a combination of these) to persons of the opposite sex or gender, the same sex or gender, or to both sexes or more than one gender. These attractions are generall ...
, although most humans are
heterosexual Heterosexuality is romantic attraction, sexual attraction or sexual behavior between people of the opposite sex or gender. As a sexual orientation, heterosexuality is "an enduring pattern of emotional, romantic, and/or sexual attractions" ...
. While homosexual behavior occurs in some other animals, only humans and
domestic sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticated ...
have so far been found to exhibit exclusive preference for same-sex relationships. Most evidence supports nonsocial, biological causes of sexual orientation, as cultures that are very tolerant of homosexuality do not have significantly higher rates of it. Research in
neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...
and
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
suggests that other aspects of human sexuality are biologically influenced as well. Love most commonly refers to a feeling of strong attraction or emotional attachment. It can be impersonal (the love of an object, ideal, or strong political or spiritual connection) or interpersonal (love between humans). When in love dopamine,
norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad' ...
, serotonin and other chemicals stimulate the brain's
pleasure center The reward system (the mesocorticolimbic circuit) is a group of neural structures responsible for incentive salience (i.e., "wanting"; desire or craving for a reward and motivation), associative learning (primarily positive reinforcement and clas ...
, leading to side effects such as increased
heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
, loss of appetite and
sleep Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
, and an intense feeling of excitement.


Culture

Humanity's unprecedented set of intellectual skills were a key factor in the species' eventual technological advancement and concomitant domination of the biosphere. Disregarding extinct hominids, humans are the only animals known to teach generalizable information, innately deploy recursive
embedding In mathematics, an embedding (or imbedding) is one instance of some mathematical structure contained within another instance, such as a group that is a subgroup. When some object X is said to be embedded in another object Y, the embedding is g ...
to generate and communicate complex concepts, engage in the "
folk physics Folk or Folks may refer to: Sociology *Nation *People * Folklore ** Folk art ** Folk dance ** Folk hero ** Folk music *** Folk metal *** Folk punk *** Folk rock ** Folk religion * Folk taxonomy Arts, entertainment, and media * Folk Plus or Fo ...
" required for competent tool design, or cook food in the wild. Teaching and learning preserves the cultural and ethnographic identity of human societies. Other traits and behaviors that are mostly unique to humans include starting fires,
phoneme In phonology and linguistics, a phoneme () is a unit of sound that can distinguish one word from another in a particular language. For example, in most dialects of English, with the notable exception of the West Midlands and the north-wes ...
structuring and
vocal learning Vocal learning is the ability to modify acoustic and syntactic sounds, acquire new sounds via imitation, and produce vocalizations. "Vocalizations" in this case refers only to sounds generated by the vocal organ (mammalian larynx or avian syrinx) as ...
.


Language

While many species
communicate Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inquir ...
,
language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...
is unique to humans, a defining feature of humanity, and a
cultural universal A cultural universal (also called an anthropological universal or human universal) is an element, pattern, trait, or institution that is common to all known human cultures worldwide. Taken together, the whole body of cultural universals is known ...
. Unlike the limited systems of other animals, human language is open—an infinite number of meanings can be produced by combining a limited number of symbols. Human language also has the capacity of
displacement Displacement may refer to: Physical sciences Mathematics and Physics * Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...
, using words to represent things and happenings that are not presently or locally occurring but reside in the shared imagination of interlocutors. Language differs from other forms of communication in that it is modality independent; the same meanings can be conveyed through different media, audibly in speech, visually by
sign language Sign languages (also known as signed languages) are languages that use the visual-manual modality to convey meaning, instead of spoken words. Sign languages are expressed through manual articulation in combination with non-manual markers. Sign l ...
or writing, and through tactile media such as
braille Braille (Pronounced: ) is a tactile writing system used by people who are visually impaired, including people who are blind, deafblind or who have low vision. It can be read either on embossed paper or by using refreshable braille disp ...
. Language is central to the communication between humans, and to the sense of identity that unites nations, cultures and ethnic groups. There are approximately six thousand different languages currently in use, including sign languages, and many thousands more that are extinct.


The arts

Human arts can take many forms including
visual The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (th ...
,
literary Literature is any collection of written work, but it is also used more narrowly for writings specifically considered to be an art form, especially prose fiction, drama, and poetry. In recent centuries, the definition has expanded to include ...
and performing. Visual art can range from
painting Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and ai ...
s and
sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable ...
s to film, interaction design and
architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...
. Literary arts can include
prose Prose is a form of written or spoken language that follows the natural flow of speech, uses a language's ordinary grammatical structures, or follows the conventions of formal academic writing. It differs from most traditional poetry, where the ...
,
poetry Poetry (derived from the Greek ''poiesis'', "making"), also called verse, is a form of literature that uses aesthetic and often rhythmic qualities of language − such as phonaesthetics, sound symbolism, and metre − to evoke meanings i ...
and
drama Drama is the specific mode of fiction represented in performance: a play, opera, mime, ballet, etc., performed in a theatre, or on radio or television.Elam (1980, 98). Considered as a genre of poetry in general, the dramatic mode has b ...
s; while the performing arts generally involve
theatre Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The perform ...
,
music Music is generally defined as the art of arranging sound to create some combination of form, harmony, melody, rhythm or otherwise expressive content. Exact definitions of music vary considerably around the world, though it is an aspe ...
and dance. Humans often combine the different forms (for example, music videos). Other entities that have been described as having artistic qualities include
food preparation Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ing ...
,
video games Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedbac ...
and
medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...
. As well as providing entertainment and transferring knowledge, the arts are also used for political purposes.
Art Art is a diverse range of human activity, and resulting product, that involves creative or imaginative talent expressive of technical proficiency, beauty, emotional power, or conceptual ideas. There is no generally agreed definition of wha ...
is a defining characteristic of humans and there is evidence for a relationship between creativity and language. The earliest evidence of art was shell engravings made by ''Homo erectus'' 300,000 years before modern humans evolved. Art attributed to ''H. sapiens'' existed at least 75,000 years ago, with jewellery and drawings found in caves in South Africa. There are various hypotheses as to why humans have
adapted In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
to the arts. These include allowing them to better problem solve issues, providing a means to control or influence other humans, encouraging cooperation and contribution within a society or increasing the chance of attracting a potential mate. The use of imagination developed through art, combined with logic may have given early humans an evolutionary advantage. Evidence of humans engaging in musical activities predates cave art and so far music has been practiced by virtually all known human cultures. There exists a wide variety of music genres and
ethnic music Folk music is a music genre that includes traditional folk music and the contemporary genre that evolved from the former during the 20th-century folk revival. Some types of folk music may be called world music. Traditional folk music has b ...
s; with humans' musical abilities being related to other abilities, including complex social human behaviours. It has been shown that human brains respond to music by becoming synchronized with the rhythm and beat, a process called entrainment. Dance is also a form of human expression found in all cultures and may have evolved as a way to help early humans communicate. Listening to music and observing dance stimulates the
orbitofrontal cortex The orbitofrontal cortex (OFC) is a prefrontal cortex region in the frontal lobes of the brain which is involved in the cognitive process of decision-making. In non-human primates it consists of the association cortex areas Brodmann area 11, 1 ...
and other pleasure sensing areas of the brain. Unlike speaking, reading and writing does not come naturally to humans and must be taught. Still,
literature Literature is any collection of written work, but it is also used more narrowly for writings specifically considered to be an art form, especially prose fiction, drama, and poetry. In recent centuries, the definition has expanded to include ...
has been present before the invention of words and language, with 30,000-year-old paintings on walls inside some caves portraying a series of dramatic scenes. One of the oldest surviving works of literature is the ''
Epic of Gilgamesh The ''Epic of Gilgamesh'' () is an epic poem from ancient Mesopotamia, and is regarded as the earliest surviving notable literature and the second oldest religious text, after the Pyramid Texts. The literary history of Gilgamesh begins with ...
'', first engraved on ancient Babylonian tablets about 4,000 years ago. Beyond simply passing down knowledge, the use and sharing of imaginative fiction through stories might have helped develop humans' capabilities for communication and increased the likelihood of securing a mate. Storytelling may also be used as a way to provide the audience with moral lessons and encourage cooperation.


Tools and technologies

Stone tools were used by proto-humans at least 2.5 million years ago. The use and manufacture of tools has been put forward as the ability that defines humans more than anything else and has historically been seen as an important evolutionary step. The technology became much more sophisticated about 1.8 million years ago, with the controlled use of fire beginning around 1 million years ago. The wheel and wheeled vehicles appeared simultaneously in several regions some time in the fourth millennium BC. The development of more complex tools and technologies allowed land to be cultivated and animals to be
domesticated Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. A ...
, thus proving essential in the development of
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...
—what is known as the Neolithic Revolution. China developed
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...
, the
printing press A printing press is a mechanical device for applying pressure to an inked surface resting upon a print medium (such as paper or cloth), thereby transferring the ink. It marked a dramatic improvement on earlier printing methods in which the ...
,
gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). Th ...
, the
compass A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself wit ...
and other important inventions. The continued improvements in
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ...
allowed forging of copper, bronze, iron and eventually steel, which is used in
railways Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a pre ...
, skyscrapers and many other products. This coincided with the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
, where the invention of automated machines brought major changes to humans' lifestyles. Modern technology is observed as progressing exponentially, with major innovations in the 20th century including:
electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describ ...
, penicillin,
semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
s,
internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...
s, the
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
, nitrogen fixing fertilisers,
airplane An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, Propeller (aircraft), propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurat ...
s, computers, automobiles, contraceptive pills, nuclear fission, the
green revolution The Green Revolution, also known as the Third Agricultural Revolution, was a period of technology transfer initiatives that saw greatly increased crop yields and agricultural production. These changes in agriculture began in developed countrie ...
,
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmi ...
, scientific plant breeding,
rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely fr ...
s,
air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
,
television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
and the
assembly line An assembly line is a manufacturing process (often called a ''progressive assembly'') in which parts (usually interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in se ...
.


Religion and spirituality

Religion is generally defined as a
belief A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to take ...
system concerning the supernatural,
sacred Sacred describes something that is dedicated or set apart for the service or worship of a deity; is considered worthy of spiritual respect or devotion; or inspires awe or reverence among believers. The property is often ascribed to objects ( ...
or
divine Divinity or the divine are things that are either related to, devoted to, or proceeding from a deity.divine< ...
, and practices,
values In ethics and social sciences, value denotes the degree of importance of something or action, with the aim of determining which actions are best to do or what way is best to live (normative ethics in ethics), or to describe the significance of di ...
, institutions and
ritual A ritual is a sequence of activities involving gestures, words, actions, or objects, performed according to a set sequence. Rituals may be prescribed by the traditions of a community, including a religious community. Rituals are characterized ...
s associated with such belief. Some religions also have a
moral code Morality () is the differentiation of intentions, decisions and actions between those that are distinguished as proper (right) and those that are improper (wrong). Morality can be a body of standards or principles derived from a code of cond ...
. The
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
and the history of the first religions have recently become areas of active scientific investigation. While the exact time when humans first became religious remains unknown, research shows credible evidence of religious behaviour from around the Middle Paleolithic era (45-200 thousand years ago). It may have evolved to play a role in helping enforce and encourage cooperation between humans. There is no accepted academic definition of what constitutes religion. Religion has taken on many forms that vary by culture and individual perspective in alignment with the geographic, social, and linguistic diversity of the planet. Religion can include a belief in life after death (commonly involving belief in an afterlife), the
origin of life In biology, abiogenesis (from a- 'not' + Greek bios 'life' + genesis 'origin') or the origin of life is the natural process by which life has arisen from non-living matter, such as simple organic compounds. The prevailing scientific hypothes ...
, the nature of the
universe The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. ...
(
religious cosmology Religious cosmology is an explanation of the origin, evolution, and eventual fate of the universe from a religious perspective. This may include beliefs on origin in the form of a creation myth, subsequent evolution, current organizational form ...
) and its ultimate fate (
eschatology Eschatology (; ) concerns expectations of the end of the present age, human history, or of the world itself. The end of the world or end times is predicted by several world religions (both Abrahamic and non-Abrahamic), which teach that nega ...
), and what is moral or immoral. A common source for answers to these questions are beliefs in transcendent divine beings such as deities or a singular
God In monotheistic thought, God is usually viewed as the supreme being, creator, and principal object of faith. Swinburne, R.G. "God" in Honderich, Ted. (ed)''The Oxford Companion to Philosophy'', Oxford University Press, 1995. God is typically ...
, although not all religions are
theistic Theism is broadly defined as the belief in the existence of a supreme being or deities. In common parlance, or when contrasted with ''deism'', the term often describes the classical conception of God that is found in monotheism (also referred t ...
. Although the exact level of religiosity can be hard to measure, a majority of humans profess some variety of religious or spiritual belief. In 2015 the plurality were Christian followed by
Muslims Muslims ( ar, المسلمون, , ) are people who adhere to Islam, a monotheistic religion belonging to the Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God of Abrah ...
,
Hindus Hindus (; ) are people who religiously adhere to Hinduism. Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for ...
and Buddhists. As of 2015, about 16%, or slightly under 1.2 billion humans, were irreligious, including those with no religious beliefs or no identity with any religion.


Science and philosophy

An aspect unique to humans is their ability to transmit knowledge from one generation to the next and to continually build on this information to develop tools,
scientific law Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow ...
s and other advances to pass on further. This accumulated knowledge can be tested to answer questions or make predictions about how the universe functions and has been very successful in advancing human ascendancy.
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
has been described as the first scientist, and preceded the rise of scientific thought through the
Hellenistic period In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in ...
. Other early advances in science came from the
Han Dynasty The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a warr ...
in China and during the
Islamic Golden Age The Islamic Golden Age was a period of cultural, economic, and scientific flourishing in the history of Islam, traditionally dated from the 8th century to the 14th century. This period is traditionally understood to have begun during the reign ...
. The
scientific revolution The Scientific Revolution was a series of events that marked the emergence of modern science during the early modern period, when developments in mathematics, physics, astronomy, biology (including human anatomy) and chemistry transfo ...
, near the end of the
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...
, led to the emergence of modern science. A chain of events and influences led to the development of the
scientific method The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...
, a process of observation and experimentation that is used to differentiate science from
pseudoscience Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable clai ...
. An understanding of mathematics is unique to humans, although other species of animals have some
numerical cognition Numerical cognition is a subdiscipline of cognitive science that studies the cognitive, developmental and neural bases of numbers and mathematics. As with many cognitive science endeavors, this is a highly interdisciplinary topic, and includes ...
. All of science can be divided into three major branches, the
formal sciences Formal science is a branch of science studying disciplines concerned with abstract structures described by formal systems, such as logic, mathematics, statistics, theoretical computer science, artificial intelligence, information theory, game t ...
(e.g.,
logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
and mathematics), which are concerned with
formal systems A formal system is an abstract structure used for inferring theorems from axioms according to a set of rules. These rules, which are used for carrying out the inference of theorems from axioms, are the logical calculus of the formal system. A form ...
, the applied sciences (e.g., engineering, medicine), which are focused on practical applications, and the empirical sciences, which are based on
empirical observation Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...
and are in turn divided into
natural sciences Natural science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and repeatab ...
(e.g.,
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, chemistry,
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
) and
social sciences Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of so ...
(e.g.,
psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...
, economics, sociology). Philosophy is a field of study where humans seek to understand fundamental truths about themselves and the world in which they live. Philosophical inquiry has been a major feature in the development of humans' intellectual history. It has been described as the "no man's land" between definitive scientific knowledge and dogmatic religious teachings. Philosophy relies on reason and evidence, unlike religion, but does not require the empirical observations and experiments provided by science. Major fields of philosophy include
metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
,
epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Epis ...
,
logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...
, and axiology (which includes
ethics Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concerns m ...
and
aesthetics Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed t ...
).


Society

Society is the system of organizations and institutions arising from interaction between humans. Humans are highly social and tend to live in large complex social groups. They can be divided into different groups according to their income, wealth,
power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...
,
reputation The reputation of a social entity (a person, a social group, an organization, or a place) is an opinion about that entity typically as a result of social evaluation on a set of criteria, such as behavior or performance. Reputation is a ubiquitous ...
and other factors. The structure of social stratification and the degree of social mobility differs, especially between modern and traditional societies. Human groups range from the size of
families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...
to nations. The first form of human social organization is thought to have resembled hunter-gatherer
band societies A band society, sometimes called a camp, or in older usage, a horde, is the simplest form of human society. A band generally consists of a small kin group, no larger than an extended family or clan. The general consensus of modern anthropology ...
.


Gender

Human societies typically exhibit gender identities and
gender role A gender role, also known as a sex role, is a social role encompassing a range of behaviors and attitudes that are generally considered acceptable, appropriate, or desirable for a person based on that person's sex. Gender roles are usually cent ...
s that distinguish between
masculine Masculinity (also called manhood or manliness) is a set of attributes, behaviors, and roles associated with men and boys. Masculinity can be theoretically understood as socially constructed, and there is also evidence that some behaviors con ...
and feminine characteristics and prescribe the range of acceptable behaviours and attitudes for their members based on their
sex Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones ( ova, of ...
. The most common categorisation is a
gender binary The gender binary (also known as gender binarism) is the classification of gender into two distinct, opposite forms of masculine and feminine, whether by social system, cultural belief, or both simultaneously. Most cultures use a gender binary ...
of
men A man is an adult male human. Prior to adulthood, a male human is referred to as a boy (a male child or adolescent). Like most other male mammals, a man's genome usually inherits an X chromosome from the mother and a Y chro ...
and
women A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or adolescent). The plural ''women'' is sometimes used in certain phrases such as "women's rights" to denote female humans regardl ...
. Many societies recognise a
third gender Third gender is a concept in which individuals are categorized, either by themselves or by society, as neither man nor woman. It is also a social category present in societies that recognize three or more genders. The term ''third'' is usuall ...
, or less commonly a fourth or fifth. In some other societies,
non-binary Non-binary and genderqueer are umbrella terms for gender identities that are not solely male or femaleidentities that are outside the gender binary. Non-binary identities fall under the transgender umbrella, since non-binary people typically ...
is used as an umbrella term for a range of gender identities that are not solely male or female. Gender roles are often associated with a division of norms, practices,
dress A dress (also known as a frock or a gown) is a garment traditionally worn by women or girls consisting of a skirt with an attached bodice (or a matching bodice giving the effect of a one-piece garment). It consists of a top piece that co ...
, behavior,
rights Rights are legal, social, or ethical principles of freedom or entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people according to some legal system, social convention, or ethical the ...
,
duties A duty (from "due" meaning "that which is owing"; fro, deu, did, past participle of ''devoir''; la, debere, debitum, whence "debt") is a commitment or expectation to perform some action in general or if certain circumstances arise. A duty may ...
, privileges,
status Status (Latin plural: ''statūs''), is a state, condition, or situation, and may refer to: * Status (law) ** City status ** Legal status, in law ** Political status, in international law ** Small entity status, in patent law ** Status confere ...
, and
power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...
, with men enjoying more rights and privileges than women in most societies, both today and in the past. As a
social construct Social constructionism is a theory in sociology, social ontology, and communication theory which proposes that certain ideas about physical reality arise from collaborative consensus, instead of pure observation of said reality. The theory ...
, gender roles are not fixed and vary historically within a society. Challenges to predominant gender norms have recurred in many societies. Little is known about gender roles in the earliest human societies. Early modern humans probably had a range of gender roles similar to that of modern cultures from at least the
Upper Paleolithic The Upper Paleolithic (or Upper Palaeolithic) is the third and last subdivision of the Paleolithic or Old Stone Age. Very broadly, it dates to between 50,000 and 12,000 years ago (the beginning of the Holocene), according to some theories coin ...
, while the
Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...
s were less sexually dimorphic and there is evidence that the behavioural difference between males and females was minimal.


Kinship

All human societies organize, recognize and classify types of social relationships based on relations between parents, children and other descendants (
consanguinity Consanguinity ("blood relation", from Latin '' consanguinitas'') is the characteristic of having a kinship with another person (being descended from a common ancestor). Many jurisdictions have laws prohibiting people who are related by blood fr ...
), and relations through
marriage Marriage, also called matrimony or wedlock, is a culturally and often legally recognized union between people called spouses. It establishes rights and obligations between them, as well as between them and their children, and between ...
(
affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Par ...
). There is also a third type applied to
godparent In infant baptism and denominations of Christianity, a godparent (also known as a sponsor, or '' gossiprede'') is someone who bears witness to a child's christening and later is willing to help in their catechesis, as well as their lifelon ...
s or adoptive children ( fictive). These culturally defined relationships are referred to as kinship. In many societies, it is one of the most important social organizing principles and plays a role in transmitting status and
inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Officia ...
. All societies have rules of
incest taboo An incest taboo is any cultural rule or norm that prohibits sexual relations between certain members of the same family, mainly between individuals related by blood. All human cultures have norms that exclude certain close relatives from ...
, according to which marriage between certain kinds of kin relations are prohibited, and some also have rules of preferential marriage with certain kin relations.


Ethnicity

Human ethnic groups are a social category that identifies together as a group based on shared attributes that distinguish them from other groups. These can be a common set of traditions,
ancestry An ancestor, also known as a forefather, fore-elder or a forebear, is a parent or (recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from whom ...
,
language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...
,
history History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the History of writing#Inventions of writing, invention of writing systems is considered prehistory. "History" is an umbr ...
,
society A society is a group of individuals involved in persistent social interaction, or a large social group sharing the same spatial or social territory, typically subject to the same political authority and dominant cultural expectations. Soci ...
,
culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
,
nation A nation is a community of people formed on the basis of a combination of shared features such as language, history, ethnicity, culture and/or society. A nation is thus the collective identity of a group of people understood as defined by those ...
,
religion Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, ...
, or social treatment within their residing area. Ethnicity is separate from the concept of
race Race, RACE or "The Race" may refer to: * Race (biology), an informal taxonomic classification within a species, generally within a sub-species * Race (human categorization), classification of humans into groups based on physical traits, and/or s ...
, which is based on physical characteristics, although both are
socially constructed Social constructionism is a theory in sociology, social ontology, and communication theory which proposes that certain ideas about physical reality arise from collaborative consensus, instead of pure observation of said reality. The theory ...
. Assigning ethnicity to a certain population is complicated, as even within common ethnic designations there can be a diverse range of subgroups, and the makeup of these ethnic groups can change over time at both the collective and individual level. Also, there is no generally accepted definition of what constitutes an ethnic group. Ethnic groupings can play a powerful role in the social identity and solidarity of ethnopolitical units. This has been closely tied to the rise of the
nation state A nation state is a political unit where the state and nation are congruent. It is a more precise concept than "country", since a country does not need to have a predominant ethnic group. A nation, in the sense of a common ethnicity, may i ...
as the predominant form of political organization in the 19th and 20th centuries.


Government and politics

As farming populations gathered in larger and denser communities, interactions between these different groups increased. This led to the development of governance within and between the communities. Humans have evolved the ability to change affiliation with various social groups relatively easily, including previously strong political alliances, if doing so is seen as providing personal advantages. This
cognitive flexibility Cognitive flexibility is an intrinsic property of a cognitive system often associated with the mental ability to adjust its activity and content, switch between different task rules and corresponding behavioral responses, maintain multiple con ...
allows individual humans to change their political ideologies, with those with higher flexibility less likely to support authoritarian and nationalistic stances. Governments create
law Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vario ...
s and policies that affect the citizens that they govern. There have been many forms of government throughout human history, each having various means of obtaining power and the ability to exert diverse controls on the population. As of 2017, more than half of all national governments are
democracies Democracy (From grc, δημοκρατία, dēmokratía, ''dēmos'' 'people' and ''kratos'' 'rule') is a form of government in which the people have the authority to deliberate and decide legislation (" direct democracy"), or to choose go ...
, with 13% being
autocracies Autocracy is a system of government in which absolute power over a state is concentrated in the hands of one person, whose decisions are subject neither to external legal restraints nor to regularized mechanisms of popular control (except perh ...
and 28% containing elements of both. Many countries have formed international political organizations and alliances, the largest being the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be ...
with 193 member states.


Trade and economics

Trade, the voluntary exchange of goods and services, is seen as a characteristic that differentiates humans from other animals and has been cited as a practice that gave ''Homo sapiens'' a major advantage over other hominids. Evidence suggests early ''H. sapiens'' made use of long-distance trade routes to exchange goods and ideas, leading to cultural explosions and providing additional food sources when hunting was sparse, while such trade networks did not exist for the now extinct Neanderthals. Early trade likely involved materials for creating tools like obsidian. The first truly international trade routes were around the spice trade through the Roman and medieval periods. Early human
economies An economy is an area of the production, distribution and trade, as well as consumption of goods and services. In general, it is defined as a social domain that emphasize the practices, discourses, and material expressions associated with the ...
were more likely to be based around
gift giving A gift or a present is an item given to someone without the expectation of payment or anything in return. An item is not a gift if that item is already owned by the one to whom it is given. Although gift-giving might involve an expectation ...
instead of a
barter In trade, barter (derived from ''baretor'') is a system of exchange in which participants in a transaction directly exchange goods or services for other goods or services without using a medium of exchange, such as money. Economists disti ...
ing system. Early
money Money is any item or verifiable record that is generally accepted as payment for goods and services and repayment of debts, such as taxes, in a particular country or socio-economic context. The primary functions which distinguish money are as ...
consisted of commodities; the oldest being in the form of cattle and the most widely used being
cowrie shells Cowrie or cowry () is the common name for a group of small to large sea snails, marine gastropod mollusks in the family Cypraeidae, the cowries. The term ''porcelain'' derives from the old Italian term for the cowrie shell (''porcellana'') du ...
. Money has since evolved into governmental issued
coins A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order t ...
,
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...
and
electronic money Digital currency (digital money, electronic money or electronic currency) is any currency, money, or money-like asset that is primarily managed, stored or exchanged on digital computer systems, especially over the internet. Types of digital cu ...
. Human study of economics is a
social science Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of soc ...
that looks at how societies distribute scarce resources among different people. There are massive
inequalities Inequality may refer to: Economics * Attention inequality, unequal distribution of attention across users, groups of people, issues in etc. in attention economy * Economic inequality, difference in economic well-being between population groups * ...
in the division of
wealth Wealth is the abundance of valuable financial assets or physical possessions which can be converted into a form that can be used for transactions. This includes the core meaning as held in the originating Old English word , which is from an I ...
among humans; the eight richest humans are worth the same monetary value as the poorest half of all the human population.


Conflict

Humans commit violence on other humans at a rate comparable to other primates, but have an increased preference for killing adults,
infanticide Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose is the prevention of reso ...
being more common among other primates. It is predicted that 2% of early ''H. sapiens'' would be murdered, rising to 12% during the medieval period, before dropping to below 2% in modern times. There is great variation in violence between human populations with rates of homicide in societies that have
legal systems The contemporary national legal systems are generally based on one of four basic systems: civil law, common law, statutory law, religious law or combinations of these. However, the legal system of each country is shaped by its unique history and ...
and strong cultural attitudes against violence at about 0.01%. The willingness of humans to kill other members of their species en masse through organized conflict (i.e., war) has long been the subject of debate. One school of thought holds that war evolved as a means to eliminate competitors, and has always been an innate human characteristic. Another suggests that war is a relatively recent phenomenon and has appeared due to changing social conditions. While not settled, current evidence indicates warlike predispositions only became common about 10,000 years ago, and in many places much more recently than that. War has had a high cost on human life; it is estimated that during the 20th century, between 167 million and 188 million people died as a result of war.


See also

* * *
List of human evolution fossils The following tables give an overview of notable finds of hominin fossils and remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the human and chimpanzee lineages) in the late Miocene, roug ...


Notes


References


External links

{{Authority control, state=expanded Apex predators Articles containing video clips Mammals described in 1758 Taxa named by Carl Linnaeus Tool-using mammals