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 huma ...
, 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' a ...
and exceptional
cognitive
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, ...
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 v ...
. This has enabled the development of advanced
tools
A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ba ...
,
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.Tyl ...
, 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 met ...
. 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. Ideall ...
and
kinship
In anthropology, kinship is the web of social relationships that form an important part of the lives of all humans in all societies, although its exact meanings even within this discipline are often debated. Anthropologist Robin Fox says that ...
networks to political
states.
Social interaction
A social relation or also described as a social interaction or social experience is the fundamental unit of analysis within the social sciences, and describes any voluntary or involuntary interpersonal relationship between two or more individuals ...
s 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, b ...
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. Socie ...
. 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 b ...
and its desire to understand and influence the environment and to explain and manipulate
phenomena
A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...
have motivated humanity's development of
science
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 ...
,
philosophy
Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. Some ...
,
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 narrat ...
,
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 by ...
.
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 relate ...
'', in common usage, it generally refers to ''Homo sapiens'', the only
extant
Extant is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Extant taxon, a taxon which is not extinct, ...
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'' in ...
'' or a similar species and migrating
out of Africa
''Out of Africa'' is a memoir by the Danish people, 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 East Africa Protectorate, British East Afr ...
, 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
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 ...
. 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 characterized by ...
about 160,000–60,000 years ago. The
Neolithic Revolution
The Neolithic Revolution, or the (First) Agricultural Revolution, was the wide-scale transition of many human cultures during the Neolithic period from a lifestyle of hunting and gathering to one of agriculture and settlement, making an incre ...
, 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 Anat ...
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 to ...
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).
Ci ...
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 ba ...
s and the
environment
Environment most often refers to:
__NOTOC__
* Natural environment, all living and non-living things occurring naturally
* Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
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 en ...
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 boy. ...
, 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 sp ...
s. Females are capable of
pregnancy
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ca ...
, 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 d ...
, 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 nutri ...
, 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 globall ...
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
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 lifesty ...
, 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 s ...
, private
thought
In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, a ...
,
imagination
Imagination is the production or simulation of novel objects, sensations, and ideas in the mind without any immediate input of the senses. Stefan Szczelkun characterises it as the forming of experiences in one's mind, which can be re-creations ...
,
volition, and forming views on
existence
Existence is the ability of an entity to interact with reality. In philosophy, it refers to the ontology, ontological Property (philosophy), property of being.
Etymology
The term ''existence'' comes from Old French ''existence'', from Medieval ...
. This has allowed great technological advancements and complex tool development possible through complex
reasoning
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, lang ...
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 ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
in his 1735 work ''
Systema Naturae
' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
''. 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 relate ...
''" 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 th ...
s, should be included as a separate species of humans or as a
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
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 th ...
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 p ...
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 intelligib ...
, 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
In lexical semantics, opposites are words lying in an inherently incompatible binary relationship. For example, something that is ''long'' entails that it is not ''short''. It is referred to as a 'binary' relationship because there are two members ...
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 property, ...
'' 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
Lineage may refer to:
Science
* Lineage (anthropology), a group that can demonstrate its common descent from an apical ancestor or a direct line of descent from an ancestor
* Lineage (evolution), a temporal sequence of individuals, populati ...
of apes that eventually gave rise to humans first split from gibbons (family
Hylobatidae
Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforest from eastern Bangladesh to Northeast India ...
) 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 genus ...
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,
chimpanzee
The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative th ...
s and
bonobo
The bonobo (; ''Pan paniscus''), also historically called the pygmy chimpanzee and less often the dwarf chimpanzee or gracile chimpanzee, is an endangered great ape and one of the two species making up the genus '' Pan,'' the other being the comm ...
s (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 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 means "less recen ...
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 relate ...
'' and its sole extant species ''Homo sapiens''—are now extinct.
![Lucy Skeleton](https://upload.wikimedia.org/wikipedia/commons/d/da/Lucy_Skeleton.jpg)
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. ''Australopi ...
''. Though
fossils
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
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 the ...
from Ethiopia, and the earliest named species are ''
Homo habilis
''Homo habilis'' ("handy man") is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.31 million years ago to 1.65 million years ago (mya). Upon species description in 1964, ''H. habilis'' was highly ...
'' 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
''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'' in ...
'' or ''
H. rhodesiensis
''Homo rhodesiensis'' is the species name proposed by Arthur Smith Woodward (1921) to classify Kabwe 1 (the "Kabwe skull" or "Broken Hill skull", also "Rhodesian Man"), a Middle Stone Age fossil recovered from a cave at Broken Hill, or Kabwe, ...
'', 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 characterized by ...
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 a ...
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 nearl ...
,
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 th ...
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 ge ...
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
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 ...
, 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 well ...
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 ani ...
(
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 compared ...
). The relationship between all these changes is the subject of ongoing debate.
History
![Early migrations mercator](https://upload.wikimedia.org/wikipedia/commons/8/8b/Early_migrations_mercator.svg)
Until about 12,000 years ago, all humans lived as
hunter-gatherer
A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi, ...
s. The
Neolithic Revolution
The Neolithic Revolution, or the (First) Agricultural Revolution, was the wide-scale transition of many human cultures during the Neolithic period from a lifestyle of hunting and gathering to one of agriculture and settlement, making an incre ...
(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 to ...
) 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 Anat ...
and spread through large parts of the
Old World
The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...
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. W ...
(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
The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid c ...
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
Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is one of the cradles of c ...
ian 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 F ...
. It was in these cities that the earliest known form of writing,
cuneiform script
Cuneiform is a logo-syllabic script that was used to write several languages of the Ancient Middle East. The script was in active use from the early Bronze Age until the beginning of the Common Era. It is named for the characteristic wedge-sha ...
, appeared around 3000 BCE. Other major civilizations to develop around this time were
Ancient Egypt and the
Indus Valley Civilization
The Indus Valley Civilisation (IVC), also known as the Indus Civilisation was a Bronze Age civilisation in the northwestern regions of South Asia, lasting from 3300 BCE to 1300 BCE, and in its mature form 2600 BCE to 1900&n ...
. 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 World, ...
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.
Babylonia
Babylonia (; Akkadian: , ''māt Akkadī'') was an ancient Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Syria). It emerged as an Amorite-ruled state c. ...
ns 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
The term Greek Dark Ages refers to the period of Greek history from the end of the Mycenaean palatial civilization, around 1100 BC, to the beginning of the Archaic age, around 750 BC. Archaeological evidence shows a widespread collaps ...
. 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 mostly appl ...
.
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 civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
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 B ...
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, archit ...
started to build cities and create
complex calendars. In Africa, the
Kingdom of Aksum
The Kingdom of Aksum ( gez, መንግሥተ አክሱም, ), also known as the Kingdom of Axum or the Aksumite Empire, was a kingdom centered in Northeast Africa and South Arabia from Classical antiquity to the Middle Ages. Based primarily in wh ...
overtook the declining
Kingdom of Kush
The Kingdom of Kush (; Egyptian language, Egyptian: 𓎡𓄿𓈙𓈉 ''kꜣš'', Akkadian language, Assyrian: ''Kûsi'', in LXX grc, Κυς and Κυσι ; cop, ''Ecōš''; he, כּוּשׁ ''Kūš'') was an ancient kingdom in Nubia, ce ...
and facilitated trade between India and the Mediterranean. In West Asia, the
Achaemenid Empire
The Achaemenid Empire or Achaemenian Empire (; peo, 𐎧𐏁𐏂, , ), also called the First Persian Empire, was an ancient Iranian empire founded by Cyrus the Great in 550 BC. Based in Western Asia, it was contemporarily the largest em ...
'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 Gol ...
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
A golden age is a period considered the apotheosis in the history of a country or people, a time period when the greatness, greatest achievements were made. The term originated from early ancient Greece, Greek and ancient Rome, Roman poets, who ...
in their respective regions.
![Invasions of the Roman Empire 1](https://upload.wikimedia.org/wikipedia/commons/2/2d/Invasions_of_the_Roman_Empire_1.png)
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 Ancient Rome, Rome) was the loss of central political control in the Western Roman Empire, a process in which the Empire failed to enforce its rul ...
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 a ...
. 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
Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic religions, Abrahamic Monotheism#Islam, monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God in Islam, God (or ...
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
Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χρι ...
and
Islamic world
The terms Muslim world and Islamic world commonly refer to the Islamic community, which is also known as the Ummah. This consists of all those who adhere to the religious beliefs and laws of Islam or to societies in which Islam is practiced. In ...
s 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 Anglo-Saxon kingdoms, until 1 May 1707, when it united with Scotland to form the Kingdom of Great Britain.
On 1 ...
, 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 Polity, political entity in Western Europe, Western, Central Europe, Central, and Southern Europe that developed during the Early Middle Ages and continued until its Dissolution of the Holy Roman Empire, dissolution i ...
declaring a series of
holy wars
A religious war or a war of religion, sometimes also known as a holy war ( la, sanctum bellum), is a war which is primarily caused or justified by differences in religion. In the modern period, there are frequent debates over the extent to wh ...
to regain control of the
Holy Land
The Holy Land; Arabic: or is an area roughly located between the Mediterranean Sea and the Eastern Bank of the Jordan River, traditionally synonymous both with the biblical Land of Israel and with the region of Palestine. The term "Holy ...
from
Muslim
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 ...
s. In the Americas, complex
Mississippian societies would arise starting around 800 CE, while further south, the
Aztecs
The Aztecs () were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different Indigenous peoples of Mexico, ethnic groups of central Mexico, particularly those g ...
and
Incas
The Inca Empire (also Quechuan and Aymaran spelling shift, known as the Incan Empire and the Inka Empire), called ''Tawantinsuyu'' by its subjects, (Quechuan languages, Quechua for the "Realm of the Four Parts", "four parts together" ) wa ...
would become the dominant powers. The
Mongol Empire
The Mongol Empire of the 13th and 14th centuries was the largest contiguous land empire in history. Originating in present-day Mongolia in East Asia, the Mongol Empire at its height stretched from the Sea of Japan to parts of Eastern Europe, ...
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 a ...
in the 13th and 14th centuries. Over this same time period, the
Mali Empire
The Mali Empire ( Manding: ''Mandé''Ki-Zerbo, Joseph: ''UNESCO General History of Africa, Vol. IV, Abridged Edition: Africa from the Twelfth to the Sixteenth Century'', p. 57. University of California Press, 1997. or Manden; ar, مالي, Māl ...
in Africa grew to be the largest empire on the continent, stretching from
Senegambia
The Senegambia (other names: Senegambia region or Senegambian zone,Barry, Boubacar, ''Senegambia and the Atlantic Slave Trade'', (Editors: David Anderson, Carolyn Brown; trans. Ayi Kwei Armah; contributors: David Anderson, American Council of Le ...
to
Ivory Coast
Ivory Coast, also known as Côte d'Ivoire, officially the Republic of Côte d'Ivoire, is a country on the southern coast of West Africa. Its capital is Yamoussoukro, in the centre of the country, while its largest city and economic centre is ...
. 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 characteriz ...
, 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-speak ...
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 marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas ...
, 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 esta ...
expanding to become the
world's largest empire and
the colonization of the Americas. This expansion led to the
Atlantic slave trade
The Atlantic slave trade, transatlantic slave trade, or Euro-American slave trade involved the transportation by slave traders of enslaved African people, mainly to the Americas. The slave trade regularly used the triangular trade route and i ...
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
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern 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 objects r ...
,
astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
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
Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image).
Imaging technology is the application of materials and methods to create, preserve, or duplicate images.
...
, major innovations in transport and
energy development
Energy development is the field of activities focused on obtaining sources of energy from natural resources. These activities include production of renewable, nuclear, and fossil fuel derived sources of energy, and for the recovery and reuse ...
. 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 superpower
A superpower is a state with a dominant position characterized by its extensive ability to exert influence or project power on a global scale. This is done through the combined means of economic, military, technological, political and cultural s ...
s. 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. 3 ...
, 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
Authoritarianism is a political system characterized by the rejection of political plurality, the use of strong central power to preserve the political ''status quo'', and reductions in the rule of law, separation of powers, and democratic votin ...
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 opposin ...
, involving
almost all of the world's countries. Following its conclusion in 1945, the
Cold War
The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...
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 tw ...
. 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, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
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. O ...
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 activity, 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 (skin), hide, ...
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 the ...
for growing crops and grazing livestock. Modern humans, however, have a great capacity for altering their
habitats
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
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 Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
,
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 d ...
and
desertification
Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by ...
.
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
A natural disaster is "the negative impact following an actual occurrence of natural hazard in the event that it significantly harms a community". A natural disaster can cause loss of life or damage property, and typically leaves some econo ...
, 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 thr ...
, 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 depe ...
, and altitudes.
As a result, humans are a
cosmopolitan
Cosmopolitan may refer to:
Food and drink
* Cosmopolitan (cocktail), also known as a "Cosmo"
History
* Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953
Hotels and resorts
* Cosmopoli ...
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 equatori ...
,
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
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
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 contine ...
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
Industrial may refer to:
Industry
* Industrial archaeology, the study of the history of the industry
* Industrial engineering, engineering dealing with the optimization of complex industrial processes or systems
* Industrial city, a city dominate ...
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
An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''body'' are often us ...
through human-made
robotic spacecraft
A robotic spacecraft is an uncrewed spacecraft, usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather t ...
. 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 ...
.
![Distribution-of-earths-mammals](https://upload.wikimedia.org/wikipedia/commons/1/17/Distribution-of-earths-mammals.png)
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 Mediterr ...
in the 4th century AD.
Bubonic plague
Bubonic plague is one of three types of plague caused by the plague bacterium (''Yersinia pestis''). One to seven days after exposure to the bacteria, flu-like symptoms develop. These symptoms include fever, headaches, and vomiting, as well a ...
s, first recorded in the 6th century AD, reduced the population by 50%, with the
Black Death
The Black Death (also known as the Pestilence, the Great Mortality or the Plague) was a bubonic plague pandemic occurring in Western Eurasia and North Africa from 1346 to 1353. It is the most fatal pandemic recorded in human history, causi ...
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 a ...
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 History of writing#Inventions of writing, invention of writing systems is considered prehistory. "History" is an umbr ...
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.e ...
and only 207 years more to grow to 7 billion. The combined
biomass
Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
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
slum
A slum is a highly populated urban residential area consisting of densely packed housing units of weak build quality and often associated with poverty. The infrastructure in slums is often deteriorated or incomplete, and they are primarily inh ...
s. 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
Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
, 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 a ...
and combustion of
fossil fuels
A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. 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. It ...
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 E ...
, which may accelerate the
Holocene extinction
The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event during the Holocene epoch. The extinctions span numerous families of bacteria, fungi, plants, and animals, including mammals, birds, reptiles, amphibians, f ...
.
Biology
Anatomy and physiology
![Anterior view of human female and male, with labels 2](https://upload.wikimedia.org/wikipedia/commons/e/e5/Anterior_view_of_human_female_and_male%2C_with_labels_2.png)
Most aspects of human physiology are closely
homologous to corresponding aspects of animal physiology. The human body consists of the
legs
A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ...
, 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 human ...
, the arms, the
neck
The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...
, and the head. An adult human body consists of about 100 trillion (10
14)
cells. The most commonly defined
body systems
A biological system is a complex network which connects several biologically relevant entities. Biological organization spans several scales and are determined based different structures depending on what the system is. Examples of biological syst ...
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 endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neu ...
, 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 reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are als ...
, 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 grea ...
, and the
urinary system
The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, urinary bladder, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and bl ...
. 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-physiolo ...
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 sepa ...
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, tear ...
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
The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.
In humans, it ...
,
hearing
Hearing, or auditory perception, is the ability to perceive sounds
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psycholog ...
and
digesting proteins.
While humans have a density of
hair follicle
The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between h ...
s 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 gland
Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...
s 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 elementar ...
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 prehensile l ...
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
![Human karyotype with bands and sub-bands](https://upload.wikimedia.org/wikipedia/commons/b/b1/Human_karyotype_with_bands_and_sub-bands.png)
Like most animals, humans are a
diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
and
eukaryotic
Eukaryotes () are organisms whose cells have a 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 three domains of life. Bacte ...
species. Each
somatic cell
A somatic cell (from Ancient Greek σῶμα ''sôma'', meaning "body"), or vegetal cell, is any biological cell forming the body of a multicellular organism other than a gamete, germ cell, gametocyte or undifferentiated stem cell. Such cells compo ...
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 t ...
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
autosome
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome, allosomal (sex chromosome) pairs, which may have different structures. The DNA in au ...
s 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 indi ...
, 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 ba ...
s and
environment
Environment most often refers to:
__NOTOC__
* Natural environment, all living and non-living things occurring naturally
* Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
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
Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, siz ...
than other great apes, including chimpanzees.
This small variation in human DNA compared to many other species suggests a
population bottleneck
A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as specicide, widespread violen ...
during the
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
(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. Charle ...
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 ge ...
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 n ...
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 a ...
had compared the genomes of 1,184 individuals from 11 populations and identified 1.6 million
single nucleotide polymorphisms
In genetics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently larg ...
. 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 region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
and
the Americas
The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North America, North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. ...
.
By 2010 estimates, humans have approximately 22,000 genes.
By comparing
mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
, 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
![Tubal Pregnancy with embryo](https://upload.wikimedia.org/wikipedia/commons/2/21/Tubal_Pregnancy_with_embryo.jpg)
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 betwe ...
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 inter ...
via
sexual intercourse
Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetrat ...
, but can also occur through
assisted reproductive technology
Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), cryopreservation of gametes o ...
procedures.
The average
gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...
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 deve ...
.
Humans are able to
induce early labor or perform a
caesarean section
Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or mo ...
if the child needs to be born earlier for medical reasons.
In developed countries,
infant
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
s 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 intensi ...
is common in developing countries, and contributes to the high levels of
infant mortality
Infant mortality is the death of young children under the age of 1. This death toll is measured by the infant mortality rate (IMR), which is the probability of deaths of children under one year of age per 1000 live births. The under-five morta ...
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
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The ...
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
Maternal death or maternal mortality is defined in slightly different ways by several different health organizations. The World Health Organization (WHO) defines maternal death as the death of a pregnant mother due to complications related to pre ...
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 definitio ...
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
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
,
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
Adolescence () is a transitional stage of physical and psychological development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority). Adolescence is usually associated with the t ...
,
adult
An adult is a human or other animal that has reached full growth. In human context, the term ''adult'' has meanings associated with social and legal concepts. In contrast to a " minor", a legal adult is a person who has attained the age of major ...
hood and
old age
Old age refers to ages nearing or surpassing the life expectancy of human beings, and is thus the end of the human life cycle. Terms and euphemisms for people at this age include old people, the elderly (worldwide usage), OAPs (British usage ...
. 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 d ...
and become
infertile
Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
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
The grandmother hypothesis is a hypothesis to explain the existence of menopause in human life history by identifying the adaptive value of extended kin networking. It builds on the previously postulated " mother hypothesis" which states that as m ...
), 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
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 ...
, 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
![Preparing The Feast](https://upload.wikimedia.org/wikipedia/commons/a/af/Preparing_The_Feast.jpg)
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 nutri ...
, 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. Di ...
to primarily
carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...
. In some cases, dietary restrictions in humans can lead to
deficiency diseases
Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues ...
; 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 developm ...
.
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
''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' ...
''. 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
A dairy is a business enterprise established for the harvesting or ...
providing a new and rich source of food, leading to the evolution of the ability to digest
lactose
Lactose is a disaccharide sugar synthesized by galactose and glucose subunits and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from ' (gen. '), the Latin word for milk, plus the suffix '' - ...
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
Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, dea ...
. 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 we ...
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
calorie
The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...
s than are expended, so excessive weight gain is usually caused by an energy-dense diet.
Biological variation
![Genetic Variation](https://upload.wikimedia.org/wikipedia/commons/e/eb/Genetic_Variation.jpg)
There is biological variation in the human species—with traits such as
blood type
A blood type (also known as a blood group) is a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrate ...
,
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 pi ...
,
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 ...
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 (c ...
,
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 abou ...
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 pattern
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 ...
s.
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-modulating ...
.
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 blo ...
, 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 proper ...
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
Blond (male) or blonde (female), also referred to as fair hair, is a hair color characterized by low levels of the dark pigment eumelanin. The resultant visible hue depends on various factors, but always has some yellowish color. The color can ...
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 used ...
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 have o ...
, 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
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...
to make. Human skin also has a capacity to darken (tan) in response to exposure to ultraviolet radiation.
![Seti1a](https://upload.wikimedia.org/wikipedia/commons/c/ce/Seti1a.jpg)
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
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
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
Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an Extinction, extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ag ...
and
Denisovans
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 ...
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
Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
, 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, Maurit ...
, 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 biomolecules wi ...
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 a ...
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 en ...
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
In music, an octave ( la, octavus: eighth) or perfect octave (sometimes called the diapason) is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been refer ...
deeper than the female voice. Women have a
longer life span in almost every population around the world.
Psychology
![NIA human brain drawing](https://upload.wikimedia.org/wikipedia/commons/a/a6/NIA_human_brain_drawing.jpg)
The
human brain
The human brain is the central 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 activities of the ...
, 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 par ...
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
In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, a ...
, reasoning, and abstraction. These mental function, cognitive processes constitute the mind, and, along with their behavioral consequences, are studied in the field of psychology.
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 intelligence, 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#Evolution and human uniqueness, mental time travel". 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 tests 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 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 dreaming, where the dreamer is self-aware. Dreams can at times make a Creativity, creative thought occur or give a sense of Artistic inspiration, inspiration.
Consciousness and thought
Human consciousness, at its simplest, is sentience or awareness 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 s ...
, private
thought
In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, a ...
,
imagination
Imagination is the production or simulation of novel objects, sensations, and ideas in the mind without any immediate input of the senses. Stefan Szczelkun characterises it as the forming of experiences in one's mind, which can be re-creations ...
and
volition.
It now often includes some kind of experience, cognition, feeling or perception. It may be 'awareness', or 'Meta-cognition, awareness of awareness', or
self-awareness
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 lifesty ...
.
There might be different levels or Higher-order theories of consciousness, 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 perception, perceives the external world through the senses, and each individual human is influenced greatly by his or her experiences, leading to subjectivity, subjective views of
existence
Existence is the ability of an entity to interact with reality. In philosophy, it refers to the ontology, ontological Property (philosophy), property of being.
Etymology
The term ''existence'' comes from Old French ''existence'', from Medieval ...
and the passage of time. The nature of thought is central to psychology and related fields. Cognitive psychology studies cognition, the mental function, mental processes 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. Psychologists have developed intelligence tests and the concept of intelligence quotient in order to assess the relative intelligence of human beings and study its Distribution (mathematics), distribution among population.
Motivation and emotion
![Plate depicting emotions of grief from Charles Darwin's book The Expression of the Emotions](https://upload.wikimedia.org/wikipedia/commons/0/0c/Plate_depicting_emotions_of_grief_from_Charles_Darwin%27s_book_The_Expression_of_the_Emotions.jpg)
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 and preference are both factors, as are any perceived links between incentives and preferences. Volition (psychology), Volition may also be involved, in which case willpower is also a factor. Ideally, both motivation and volition ensure the selection, striving for, and Realisation (metrology), realization of goals in an optimal manner, a Function (biology), function beginning in childhood and continuing throughout a lifetime in a process known as socialization.
Emotions are biological states associated with the nervous system brought on by Neurophysiology, neurophysiological changes variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or Suffering, displeasure.
They are often Reciprocal influence, intertwined with Mood (psychology), mood, temperament, Personality psychology, personality, disposition, creativity, 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 than normal.
Emotional experiences perceived as pleasure, pleasant, such as joy, Interest (emotion), interest or contentment, contrast with those perceived as suffering, unpleasant, like anxiety, sadness, anger, and Depression (mood), despair. Happiness, 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 Affect (psychology), emotional affects, while avoiding the negative ones. Others see it as an appraisal of life satisfaction or quality of life. Recent research suggests that being happy might involve experiencing some negative emotions when humans feel they are warranted.
Sexuality and love
![Sweet Baby Kisses Family Love](https://upload.wikimedia.org/wikipedia/commons/1/1f/Sweet_Baby_Kisses_Family_Love.jpg)
For humans, sexuality involves biological, erotic, Physical intimacy, physical, Emotional intimacy, emotional, social, or Spirituality, 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 reproduction, human reproductive functions, including the human sexual response cycle.
Sexuality also affects and is affected by cultural, political, legal, philosophical, Morality, moral, ethical, and religious aspects of life.
Sexual desire, or ''libido'', is a basic mental state present at the beginning of sexual behavior. Studies show that men desire sex more than women and Masturbation, masturbate more often.
Humans can fall anywhere along a continuous scale of sexual orientation,
although most humans are heterosexual.
While homosexuality, homosexual behavior Homosexual behavior in animals, occurs in some other animals, only humans and Sheep, domestic sheep have so far been found to exhibit exclusive preference for same-sex relationships.
Most evidence supports nonsocial, biology and sexual orientation, biological causes of sexual orientation,
as cultures that are very tolerant of homosexuality do not have significantly higher rates of it.
Research in neuroscience and genetics 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 (psychology), 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, serotonin and other chemicals stimulate the brain's pleasure center, leading to side effects such as increased heart rate, loss of Anorexia (symptom), appetite and Insomnia, sleep, and an Euphoria, 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 to generate and communicate complex concepts, engage in the "folk physics" 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 structuring and vocal learning.
Language
While many species animal communication, communicate,
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 met ...
is unique to humans, a defining feature of humanity, and a cultural universal. 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 (linguistics), displacement, 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 Origin of speech#Modality-independence, modality independent; the same meanings can be conveyed through different media, audibly in speech, visually by sign language or writing, and through tactile media such as braille. 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 language, extinct.
The arts
Human arts can take many forms including Visual arts, visual, Literary arts, literary and Performing arts, performing. Visual art can range from paintings and sculptures 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, poetry and dramas; while the performing arts generally involve theatre, music and dance. Humans often combine the different forms (for example, music videos). Other entities that have been described as having artistic qualities include Culinary arts, food preparation, Video games as an art form, video games and medicine. As well as providing entertainment and transferring knowledge, the arts are also used for The arts and politics, political purposes.
![British Museum Flood Tablet](https://upload.wikimedia.org/wikipedia/commons/7/7a/British_Museum_Flood_Tablet.jpg)
Art 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 Adaptation, adapted 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 Cultural universal, practiced by virtually all known human cultures.
There exists a wide variety of music genres and ethnic musics; 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 (biomusicology), 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 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 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'', first engraved on ancient
Babylonia
Babylonia (; Akkadian: , ''māt Akkadī'') was an ancient Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Syria). It emerged as an Amorite-ruled state c. ...
n 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
![JR-Maglev-MLX01-2](https://upload.wikimedia.org/wikipedia/commons/9/9f/JR-Maglev-MLX01-2.jpg)
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 Control of fire by early humans, 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 Arable land, cultivated and animals to be Domestication, domesticated, 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 to ...
—what is known as the
Neolithic Revolution
The Neolithic Revolution, or the (First) Agricultural Revolution, was the wide-scale transition of many human cultures during the Neolithic period from a lifestyle of hunting and gathering to one of agriculture and settlement, making an incre ...
.
China developed paper, the printing press, gunpowder, the compass and List of Chinese inventions, other important inventions. The continued improvements in smelting allowed forging of copper, bronze, iron and eventually steel, which is used in railways, 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 Accelerating change, progressing exponentially, with major innovations in the 20th century including: Electricity generation, electricity, penicillin, semiconductors, internal combustion engines, the Internet, Fertilizer, nitrogen fixing fertilisers, airplanes, computers, Car, automobiles, Combined oral contraceptive pill, contraceptive pills, nuclear fission, the Green Revolution, green revolution, radio, scientific plant breeding, rockets, air conditioning, television and the assembly line.
Religion and spirituality
![Brooklyn Museum 1992](https://upload.wikimedia.org/wikipedia/commons/2/24/Brooklyn_Museum_1992.133.4_Figure_of_Shango_on_Horseback.jpg)
Religion is generally defined as a belief system concerning the supernatural, sacred or divinity, divine, and practices, values, 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, b ...
s associated with such belief. Some religions also have a moral code. The Evolutionary psychology of religion, evolution and the history of the Evolutionary origin of religions, 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 Tya (unit), 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, the nature of the universe (religious cosmology) and its ultimate fate (eschatology), and what is morality, moral or immoral. A common source for answers to these questions are beliefs in transcendence (religion), transcendent divine beings such as deities or a singular God, although not all religions are theistic.
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 Christians, Christian followed by Muslims, Hindus and Buddhism, 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
![Dunhuang star map](https://upload.wikimedia.org/wikipedia/commons/4/42/Dunhuang_star_map.jpg)
An aspect unique to humans is their ability to Knowledge transfer, transmit knowledge from one generation to the next and to continually build on this information to develop tools, scientific laws 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 has been described as the first scientist, and preceded the rise of scientific thought through the Hellenistic period. Other early advances in science came from the Science and technology of the Han dynasty, Han Dynasty 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, scientific revolution, near the end of the
Renaissance
The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas ...
, led to the emergence of modern science.
A chain of events and influences led to the development of the scientific method, a process of observation and experimentation that is used to differentiate science from pseudoscience. An understanding of
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
is unique to humans, although other species of animals have some numerical cognition. All of science can be divided into three major branches, the formal sciences (e.g., logic and
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
), which are concerned with formal systems, the applied sciences (e.g., engineering, medicine), which are focused on practical applications, and the empirical sciences, which are based on empirical observation and are in turn divided into natural sciences (e.g., physics, chemistry, biology) and social sciences (e.g., psychology, 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, epistemology, Logic (philosophy), logic, and axiology (which includes ethics 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 thr ...
).
Society
![Indian family in Brazil posed in front of hut](https://upload.wikimedia.org/wikipedia/commons/0/06/Indian_family_in_Brazil_posed_in_front_of_hut.jpg)
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 (social and political), power, reputation 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 Family, families to nations. The first form of human social organization is thought to have resembled
hunter-gatherer
A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi, ...
Band society, band societies.
Gender
Human societies typically exhibit Gender identity, gender identities and gender roles that distinguish between Masculinity, masculine and Femininity, 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 of men and women.
Many societies recognise a third gender, or less commonly a fourth or fifth.
In some other societies, Non-binary gender, non-binary 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 social norm, norms, practice (social theory), practices, clothing, dress, social behavior, behavior, rights, duty, duties, Privilege (social inequality), privileges, social status, status, and power (social and political), power, with men enjoying more rights and privileges than women in most societies, both today and in the past. As a Social constructionism, social construct,
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, 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 th ...
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), and relations through marriage (Affinity (law), affinity). There is also a third type applied to godparents or Adoption, adoptive children (Fictive kinship, 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. All societies have rules of incest taboo, 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 Identity (social science), identifies together as a group based on shared attributes that distinguish them from other groups. These can be a common set of traditions, ancestry,
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 met ...
, history,
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. Socie ...
,
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.Tyl ...
, nation,
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 (human categorization), race, which is based on physical characteristics, although both are socially constructed. 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 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 allows individual humans to change their political ideologies, with those with higher flexibility less likely to support authoritarian and nationalistic stances.
Governments create laws and policies that affect the citizens that they govern. There have been List of forms of government, 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 democracy, democracies, with 13% being autocracy, autocracies and 28% containing elements of both. Many countries have formed Intergovernmental organization, international political organizations and alliances, the largest being the United Nations with 193 member states.
Trade and economics
![Silk route](https://upload.wikimedia.org/wikipedia/commons/7/74/Silk_route.jpg)
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 Economy, economies were more likely to be based around Gift economy, gift giving instead of a bartering system. Early money consisted of Commodity money, commodities; the oldest being in the form of cattle and the most widely used being cowrie shells.
Money has since evolved into governmental issued coins, Paper money, paper and electronic money.
Human study of economics is a social science that looks at how societies distribute scarce resources among different people. There are massive Economic inequality, inequalities in the division of wealth 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 (zoology), infanticide 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 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
Notes
References
External links
{{Authority control, state=expanded
Humans,
Apex predators
Articles containing video clips
Mammals described in 1758
Taxa named by Carl Linnaeus
Tool-using mammals