modern Modern may refer to: History * Modern history ** Early Modern period ** Late Modern period *** 18th century *** 19th century *** 20th century ** Contemporary history * Moderns, a faction of Freemasonry that existed in the 18th century Phil ...

biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...

Ayurveda Ayurveda () is an alternative medicine system with historical roots in the Indian subcontinent. The theory and practice of Ayurveda is pseudoscientific. Ayurveda is heavily practiced in India and Nepal, where around 80% of the population repo ...

ancient Egyptian medicine The medicine of the ancient Egyptians is some of the oldest documented. From the beginnings of the civilization in the late fourth millennium BC until the Persian invasion of 525 BC, Egyptian medical practice went largely unchanged and include ...

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...

Galen Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one of ...

Greco-Roman world The Greco-Roman civilization (; also Greco-Roman culture; spelled Graeco-Roman in the Commonwealth), as understood by modern scholars and writers, includes the geographical regions and countries that culturally—and so historically—were di ...

Avicenna Ibn Sina ( fa, ابن سینا; 980 – June 1037 CE), commonly known in the West as Avicenna (), was a Persian polymath who is regarded as one of the most significant physicians, astronomers, philosophers, and writers of the Islamic G ...

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 ...

empiricism In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empir ...

Harvey Harvey, Harveys or Harvey's may refer to: Arts, entertainment, and media * ''Harvey'' (play), a 1944 play by Mary Chase about a man befriended by an invisible anthropomorphic rabbit * Harvey Awards ("Harveys"), one of the most important awards ...

Antonie van Leeuwenhoek Antonie Philips van Leeuwenhoek ( ; ; 24 October 1632 – 26 August 1723) was a Dutch microbiologist and microscopist in the Golden Age of Dutch science and technology. A largely self-taught man in science, he is commonly known as " the ...

microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...

natural theology Natural theology, once also termed physico-theology, is a type of theology that seeks to provide arguments for theological topics (such as the existence of a deity) based on reason and the discoveries of science. This distinguishes it from ...

mechanical philosophy The mechanical philosophy is a form of natural philosophy which compares the universe to a large-scale mechanism (i.e. a machine). The mechanical philosophy is associated with the scientific revolution of early modern Europe. One of the first expos ...

botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...

zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

scientific discipline The branches of science, also referred to as sciences, scientific fields or scientific disciplines, are commonly divided into three major groups: *Formal sciences: the study of formal systems, such as those under the branches of logic and mat ...

Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS (

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister, p ...

investigated the interaction between organisms and their environment, and the ways this relationship depends on geography—laying the foundations for

biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

,

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

and

ethology Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objectiv ...

. Naturalists began to reject

essentialism Essentialism is the view that objects have a set of attributes that are necessary to their identity. In early Western thought, Plato's idealism held that all things have such an "essence"—an "idea" or "form". In ''Categories'', Aristotle sim ...

and consider the importance of

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

and the mutability of species. Cell theory provided a new perspective on the fundamental basis of life. These developments, as well as the results from

embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...

and

paleontology Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

, were synthesized in

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...

's theory of

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

by

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 ...

. The end of the 19th century saw the fall of spontaneous generation and the rise of the

germ theory of disease The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to be seen without magnification, invade h ...

, though the mechanism of

inheritance Inheritance is the practice of receiving private property, Title (property), titles, debts, entitlements, Privilege (law), privileges, rights, and Law of obligations, obligations upon the death of an individual. The rules of inheritance differ ...

remained a mystery. In the early 20th century, the rediscovery of Mendel's work led to the rapid development of

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

by Thomas Hunt Morgan and his students, and by the 1930s the combination of

population genetics Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and pop ...

and natural selection in the " neo-Darwinian synthesis". New disciplines developed rapidly, especially after

Watson Watson may refer to: Companies * Actavis, a pharmaceutical company formerly known as Watson Pharmaceuticals * A.S. Watson Group, retail division of Hutchison Whampoa * Thomas J. Watson Research Center, IBM research center * Watson Systems, make ...

and

Crick Crick may refer to: Places * Crick, Monmouthshire, Wales * Crick, Northamptonshire, England * Crick Road, Oxford, England People with the name * Crick (surname) Other uses * Crick, the cricket from ''Beat Bugs'' * Francis Crick Institute ...

proposed the structure of DNA. Following the establishment of the

Central Dogma The central dogma of molecular biology is an explanation of the flow of genetic information within a biological system. It is often stated as "DNA makes RNA, and RNA makes protein", although this is not its original meaning. It was first stated by ...

and the cracking of the genetic code, biology was largely split between ''organismal biology''—the fields that deal with whole organisms and groups of organisms—and the fields related to ''

cellular Cellular may refer to: *Cellular automaton, a model in discrete mathematics * Cell biology, the evaluation of cells work and more * ''Cellular'' (film), a 2004 movie *Cellular frequencies, assigned to networks operating in cellular RF bands *Cell ...

and

molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

''. By the late 20th century, new fields like

genomics Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dim ...

and

proteomics Proteomics is the large-scale study of proteins. Proteins are vital parts of living organisms, with many functions such as the formation of structural fibers of muscle tissue, enzymatic digestion of food, or synthesis and replication of DNA. In ...

were reversing this trend, with organismal biologists using molecular techniques, and molecular and cell biologists investigating the interplay between genes and the environment, as well as the genetics of natural populations of organisms.

Prehistoric times

The

earliest 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) fr ...

must have had and passed on knowledge about

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s and

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

s to increase their chances of survival. This may have included knowledge of human and animal anatomy and aspects of animal behavior (such as migration patterns). However, the first major turning point in biological knowledge came with 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 ...

about 10,000 years ago. Humans first domesticated plants for farming, then

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...

animals to accompany the resulting sedentary societies.

Earliest roots

In around 3000 to 1200 BCE, the Ancient Egyptians and

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 ...

ns made contributions to

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 ...

,

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 ...

, and

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...

, which later entered and shaped Greek

natural philosophy Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...

of

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 ...

, a period that profoundly influenced the development of what came to be known as biology.

Ancient Egypt

Over a dozen

medical papyri Egyptian medical papyri are ancient Egyptian texts written on papyrus which permit a glimpse at medical procedures and practices in ancient Egypt. These papyri give details on disease, diagnosis, and remedies of disease, which include herbal re ...

have been preserved, most notably the

Edwin Smith Papyrus The Edwin Smith Papyrus is an ancient Egyptian medical text, named after Edwin Smith who bought it in 1862, and the oldest known surgical treatise on trauma. From a cited quotation in another text, it may have been known to ancient surgeons as t ...

(the oldest extant surgical handbook) and the Ebers Papyrus (a handbook of preparing and using materia medica for various diseases), both from around 1600 BCE. Ancient Egypt is also known for developing embalming, which was used for mummification, in order to preserve human remains and forestall

decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...

.

Mesopotamia

The Mesopotamians seem to have had little interest in the natural world as such, preferring to study how the gods had ordered the universe.

Animal 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 an ...

was studied for

divination Divination (from Latin ''divinare'', 'to foresee, to foretell, to predict, to prophesy') is the attempt to gain insight into a question or situation by way of an occultic, standardized process or ritual. Used in various forms throughout histor ...

, including especially the anatomy of the

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

, seen as an important organ in

haruspicy In the religion of ancient Rome, a haruspex (plural haruspices; also called aruspex) was a person trained to practise a form of divination called haruspicy (''haruspicina''), the inspection of the entrails (''exta''—hence also extispicy ( ...

.

Animal behavior Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objective ...

too was studied for divinatory purposes. Most information about the training and domestication of animals was probably transmitted orally, but one text dealing with the training of horses has survived. The ancient Mesopotamians had no distinction between "rational science" and

magic Magic or Magick most commonly refers to: * Magic (supernatural), beliefs and actions employed to influence supernatural beings and forces * Ceremonial magic, encompasses a wide variety of rituals of magic * Magical thinking, the belief that unrela ...

. When a person became ill, doctors prescribed both magical formulas to be recited and medicinal treatments. The earliest medical prescriptions appear in

Sumerian Sumerian or Sumerians may refer to: *Sumer, an ancient civilization **Sumerian language **Sumerian art **Sumerian architecture **Sumerian literature **Cuneiform script, used in Sumerian writing *Sumerian Records, an American record label based in ...

during the

Third Dynasty of Ur The Third Dynasty of Ur, also called the Neo-Sumerian Empire, refers to a 22nd to 21st century Common Era, BC (middle chronology) Sumerian ruling dynasty based in the city of Ur and a short-lived territorial-political state which some historians c ...

( 2112 – 2004 BCE). The most extensive Babylonian medical text, however, is the ''Diagnostic Handbook'' written by the ''ummânū'', or chief scholar,

Esagil-kin-apli Esagil-kin-apli was the ''ummânū'', or chief scholar, of Babylonian king Adad-apla-iddina, 1067–1046 BCE, as he appears on the Uruk ''List of Sages and Scholars'' (165 BCE)W 20030,7 the Seleucid ''List of Sages and Scholars'', obverse line 16, r ...

of

Borsippa Borsippa ( Sumerian: BAD.SI.(A).AB.BAKI; Akkadian: ''Barsip'' and ''Til-Barsip'')The Cambridge Ancient History: Prolegomena & Prehistory': Vol. 1, Part 1. Accessed 15 Dec 2010. or Birs Nimrud (having been identified with Nimrod) is an archeologi ...

, during the reign of the Babylonian king

Adad-apla-iddina Adad-apla-iddina, typically inscribed in cuneiform mdIM- DUMU.UŠ-SUM''-na'', mdIM-A-SUM''-na'' or dIM''-ap-lam-i-din-'' 'nam''meaning the storm god “Adad has given me an heir”, was the 8th king of the 2nd Dynasty of Isin and the 4th Dynasty ...

(1069 – 1046 BCE). In East Semitic cultures, the main medicinal authority was an exorcist-healer known as an '' āšipu''. The profession was passed down from father to son and was held in high regard. Of less frequent recourse was the ''asu'', a healer who treated physical symptoms using remedies composed of herbs, animal products, and minerals, as well as potions, enemas, and ointments or

poultices A poultice, also called a cataplasm, is a soft moist mass, often heated and medicated, that is spread on cloth and placed over the skin to treat an aching, inflammation, inflamed, or painful part of the body. It can be used on wounds, such as cut ...

. These physicians, who could be either male or female, also dressed wounds, set limbs, and performed simple surgeries. The ancient Mesopotamians also practiced prophylaxis and took measures to prevent the spread of disease.

Separate developments in China and India

Observations and theories regarding nature and human health, separate from Western traditions, had emerged independently in other civilizations such as those in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and the

Indian subcontinent The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...

. In ancient China, earlier conceptions can be found dispersed across several different disciplines, including the work of herbologists, physicians, alchemists, and philosophers. The

Taoist Taoism (, ) or Daoism () refers to either a school of philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of Chinese origin and emphasize living in harmony with the ''Tao'' ...

tradition of Chinese alchemy, for example, emphasized health (with the ultimate goal being the

elixir of life The elixir of life, also known as elixir of immortality, is a potion that supposedly grants the drinker eternal life and/or eternal youth. This elixir was also said to cure all diseases. Alchemists in various ages and cultures sought the means ...

). The system of

classical Chinese medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of action ...

usually revolved around the theory of

yin and yang Yin and yang ( and ) is a Chinese philosophy, Chinese philosophical concept that describes opposite but interconnected forces. In Chinese cosmology, the universe creates itself out of a primary chaos of material energy, organized into the c ...

, and the

five phases (; Japanese: (); Korean: (); Vietnamese: ''ngũ hành'' (五行)), usually translated as Five Phases or Five Agents, is a fivefold conceptual scheme that many traditional Chinese fields used to explain a wide array of phenomena, from cosmi ...

. Taoist philosophers, such as

Zhuangzi Zhuangzi may refer to: * ''Zhuangzi'' (book) (莊子), an ancient Chinese collection of anecdotes and fables, one of the foundational texts of Daoism **Zhuang Zhou Zhuang Zhou (), commonly known as Zhuangzi (; ; literally "Master Zhuang"; als ...

in the 4th century BCE, also expressed ideas related to

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

, such as denying the fixity of biological species and speculating that species had developed differing attributes in response to differing environments. One of the oldest organised systems of medicine is known from ancient India in the form of

Ayurveda Ayurveda () is an alternative medicine system with historical roots in the Indian subcontinent. The theory and practice of Ayurveda is pseudoscientific. Ayurveda is heavily practiced in India and Nepal, where around 80% of the population repo ...

, which originated around 1500 BCE from

Atharvaveda The Atharva Veda (, ' from ' and ''veda'', meaning "knowledge") is the "knowledge storehouse of ''atharvāṇas'', the procedures for everyday life".Laurie Patton (2004), Veda and Upanishad, in ''The Hindu World'' (Editors: Sushil Mittal and G ...

(one of the four most ancient books of Indian knowledge, wisdom and culture). The ancient Indian

Ayurveda Ayurveda () is an alternative medicine system with historical roots in the Indian subcontinent. The theory and practice of Ayurveda is pseudoscientific. Ayurveda is heavily practiced in India and Nepal, where around 80% of the population repo ...

tradition independently developed the concept of three humours, resembling that of the four humours of

ancient Greek medicine Ancient Greek medicine was a compilation of theories and practices that were constantly expanding through new ideologies and trials. Many components were considered in ancient Greek medicine, intertwining the spiritual with the physical. Specifi ...

, though the Ayurvedic system included further complications, such as the body being composed of five elements and seven basic tissues. Ayurvedic writers also classified living things into four categories based on the method of birth (from the womb, eggs, heat & moisture, and seeds) and explained the conception of 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 ...

in detail. They also made considerable advances in the field of

surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

, often without the use of human

dissection Dissection (from Latin ' "to cut to pieces"; also called anatomization) is the dismembering of the body of a deceased animal or plant to study its anatomical structure. Autopsy is used in pathology and forensic medicine to determine the cause o ...

or animal

vivisection Vivisection () is surgery conducted for experimental purposes on a living organism, typically animals with a central nervous system, to view living internal structure. The word is, more broadly, used as a pejorative catch-all term for experiment ...

. One of the earliest Ayurvedic treatises was the ''

Sushruta Samhita The ''Sushruta Samhita'' (सुश्रुतसंहिता, IAST: ''Suśrutasaṃhitā'', literally "Suśruta's Compendium") is an ancient Sanskrit text on medicine and surgery, and one of the most important such treatises on this subj ...

'', attributed to Sushruta in the 6th century BCE. It was also an early materia medica, describing 700 medicinal plants, 64 preparations from mineral sources, and 57 preparations based on animal sources.

Classical antiquity

The

pre-Socratic philosophers Pre-Socratic philosophy, also known as early Greek philosophy, is ancient Greek philosophy before Socrates. Pre-Socratic philosophers were mostly interested in cosmology, the beginning and the substance of the universe, but the inquiries of thes ...

asked many questions about life but produced little systematic knowledge of specifically biological interest—though the attempts of the atomists to explain life in purely physical terms would recur periodically through the history of biology. However, the medical theories of

Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history of ...

and his followers, especially

humorism Humorism, the humoral theory, or humoralism, was a system of medicine detailing a supposed makeup and workings of the human body, adopted by Ancient Greek and Roman physicians and philosophers. Humorism began to fall out of favor in the 1850s ...

, had a lasting impact. The philosopher

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...

was the most influential scholar of the living world from

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 ...

. Though his early work in natural philosophy was speculative, Aristotle's later biological writings were more empirical, focusing on biological causation and the diversity of life. He made countless observations of nature, especially the habits and attributes of

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s and

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

s in the world around him, which he devoted considerable attention to

categorizing Categorization is the ability and activity of recognizing shared features or similarities between the elements of the experience of the world (such as objects, events, or ideas), organizing and classifying experience by associating them to a ...

. In all, Aristotle classified 540 animal species, and dissected at least 50. He believed that intellectual purposes,

formal cause The four causes or four explanations are, in Aristotelian thought, four fundamental types of answer to the question "why?", in analysis of change or movement in nature: the material, the formal, the efficient, and the final. Aristotle wrote th ...

s, guided all natural processes. Aristotle, and nearly all Western scholars after him until the 18th century, believed that creatures were arranged in a graded scale of perfection rising from plants on up to humans: the ''scala naturae'' or Great Chain of Being. Aristotle's successor at the Lyceum,

Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routledge ...

, wrote a series of books on botany—the '' History of Plants''—which survived as the most important contribution of antiquity to botany, even into 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 ...

. Many of Theophrastus' names survive into modern times, such as ''carpos'' for fruit, and ''pericarpion'' for seed vessel.

Dioscorides Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of ''De materia medica'' (, On Medical Material) —a 5-vol ...

wrote a pioneering and

encyclopaedic An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline. Encyclopedias are divided into articles ...

pharmacopoeia A pharmacopoeia, pharmacopeia, or pharmacopoea (from the obsolete typography ''pharmacopœia'', meaning "drug-making"), in its modern technical sense, is a book containing directions for the identification of compound medicines, and published by ...

, '' De Materia Medica'', incorporating descriptions of some 600 plants and their uses in

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...

.

Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...

, in his '' Natural History'', assembled a similarly encyclopaedic account of things in nature, including accounts of many plants and animals. A few scholars in the

Hellenistic period In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in 3 ...

under the

Ptolemies The Ptolemaic dynasty (; grc, Πτολεμαῖοι, ''Ptolemaioi''), sometimes referred to as the Lagid dynasty (Λαγίδαι, ''Lagidae;'' after Ptolemy I's father, Lagus), was a Macedonian Greek royal dynasty which ruled the Ptolemaic K ...

—particularly

Herophilus of Chalcedon Herophilos (; grc-gre, Ἡρόφιλος; 335–280 BC), sometimes Latinised Herophilus, was a Greek physician regarded as one of the earliest anatomists. Born in Chalcedon, he spent the majority of his life in Alexandria. He was the first sci ...

and

Erasistratus of Chios Erasistratus (; grc-gre, Ἐρασίστρατος; c. 304 – c. 250 BC) was a Greek anatomist and royal physician under Seleucus I Nicator of Syria. Along with fellow physician Herophilus, he founded a school of anatomy in Alexandria, where the ...

—amended Aristotle's physiological work, even performing dissections and vivisections.

Claudius Galen Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one ...

became the most important authority on medicine and anatomy. Though a few ancient atomists such as

Lucretius Titus Lucretius Carus ( , ; – ) was a Roman poet and philosopher. His only known work is the philosophical poem ''De rerum natura'', a didactic work about the tenets and philosophy of Epicureanism, and which usually is translated into E ...

challenged the teleological Aristotelian viewpoint that all aspects of life are the result of design or purpose, teleology (and after the rise of

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 ...

,

natural theology Natural theology, once also termed physico-theology, is a type of theology that seeks to provide arguments for theological topics (such as the existence of a deity) based on reason and the discoveries of science. This distinguishes it from ...

) would remain central to biological thought essentially until the 18th and 19th centuries.

Ernst W. Mayr Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His ...

argued that "Nothing of any real consequence happened in biology after Lucretius and Galen until the Renaissance." The ideas of the Greek traditions of natural history and medicine survived, but they were generally taken unquestioningly in

medieval Europe 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 ...

.

Middle Ages

The decline of the

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 ...

led to the disappearance or destruction of much knowledge, though physicians still incorporated many aspects of the Greek tradition into training and practice. In

Byzantium Byzantium () or Byzantion ( grc, Βυζάντιον) was an ancient Greek city in classical antiquity that became known as Constantinople in late antiquity and Istanbul today. The Greek name ''Byzantion'' and its Latinization ''Byzantium'' cont ...

and the

Islamic Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God (or '' Allah'') as it was revealed to Muhammad, the mai ...

world, many of the Greek works were translated into

Arabic Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...

and many of the works of Aristotle were preserved.Mayr, ''The Growth of Biological Thought'', pp 91–94 Frederick II and eagle

During the

High Middle Ages The High Middle Ages, or High Medieval Period, was the periodization, period of European history that lasted from AD 1000 to 1300. The High Middle Ages were preceded by the Early Middle Ages and were followed by the Late Middle Ages, which ended ...

, a few European scholars such as Hildegard of Bingen, Albertus Magnus and Frederick II wrote on natural history. The rise of European universities, though important for the development of physics and philosophy, had little impact on biological scholarship.

Renaissance

The

European 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 ...

brought expanded interest in both empirical natural history and physiology. In 1543, Andreas Vesalius inaugurated the modern era of Western medicine with his seminal

human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a he ...

treatise ''

De humani corporis fabrica ''De Humani Corporis Fabrica Libri Septem'' (Latin, lit. "On the fabric of the human body in seven books") is a set of books on human anatomy written by Andreas Vesalius (1514–1564) and published in 1543. It was a major advance in the history ...

'', which was based on dissection of corpses. Vesalius was the first in a series of anatomists who gradually replaced

scholasticism Scholasticism was a medieval school of philosophy that employed a critical organic method of philosophical analysis predicated upon the Aristotelian 10 Categories. Christian scholasticism emerged within the monastic schools that translate ...

with

empiricism In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empir ...

in physiology and medicine, relying on first-hand experience rather than authority and abstract reasoning. Via

herbalism Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern reme ...

, medicine was also indirectly the source of renewed empiricism in the study of plants. Otto Brunfels,

Hieronymus Bock Hieronymus Bock ( Latinised Hieronymus Tragus; c. 1498 – 21 February 1554) was a German botanist, physician, and Lutheran minister who began the transition from medieval botany to the modern scientific worldview by arranging plants by their re ...

and

Leonhart Fuchs Leonhart Fuchs (; 17 January 1501 – 10 May 1566), sometimes spelled Leonhard Fuchs and cited in Latin as ''Leonhartus Fuchsius'', was a German physician and botanist. His chief notability is as the author of a large book about plants and th ...

wrote extensively on wild plants, the beginning of a nature-based approach to the full range of plant life. Bestiaries—a genre that combines both the natural and figurative knowledge of animals—also became more sophisticated, especially with the work of William Turner, Pierre Belon, Guillaume Rondelet, Conrad Gessner, and Ulisse Aldrovandi. Artists such as

Albrecht Dürer Albrecht Dürer (; ; hu, Ajtósi Adalbert; 21 May 1471 – 6 April 1528),Müller, Peter O. (1993) ''Substantiv-Derivation in Den Schriften Albrecht Dürers'', Walter de Gruyter. . sometimes spelled in English as Durer (without an umlaut) or Due ...

and

Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, Drawing, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially res ...

, often working with naturalists, were also interested in the bodies of animals and humans, studying physiology in detail and contributing to the growth of anatomical knowledge. The traditions of

alchemy Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...

and natural magic, especially in the work of

Paracelsus Paracelsus (; ; 1493 – 24 September 1541), born Theophrastus von Hohenheim (full name Philippus Aureolus Theophrastus Bombastus von Hohenheim), was a Swiss physician, alchemist, lay theologian, and philosopher of the German Renaissance. He w ...

, also laid claim to knowledge of the living world. Alchemists subjected organic matter to chemical analysis and experimented liberally with both biological and mineral

pharmacology Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemica ...

. This was part of a larger transition in world views (the rise of the

mechanical philosophy The mechanical philosophy is a form of natural philosophy which compares the universe to a large-scale mechanism (i.e. a machine). The mechanical philosophy is associated with the scientific revolution of early modern Europe. One of the first expos ...

) that continued into the 17th century, as the traditional metaphor of ''nature as organism'' was replaced by the ''nature as machine'' metaphor.

Age of Enlightenment

Systematizing, naming and classifying dominated natural history throughout much of the 17th and 18th centuries.

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 ...

published a basic

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

for the natural world in 1735 (variations of which have been in use ever since), and in the 1750s introduced scientific names for all his species. While Linnaeus conceived of species as unchanging parts of a designed hierarchy, the other great naturalist of the 18th century, Georges-Louis Leclerc, Comte de Buffon, treated species as artificial categories and living forms as malleable—even suggesting the possibility of

common descent Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. All living beings are in fact descendants of a unique ancestor commonly referred to as the last universal comm ...

. Though he was opposed to evolution, Buffon is a key figure in the history of evolutionary thought; his work would influence the evolutionary theories of both Lamarck and Darwin. The discovery and description of new species and the

collection Collection or Collections may refer to: * Cash collection, the function of an accounts receivable department * Collection (church), money donated by the congregation during a church service * Collection agency, agency to collect cash * Collectio ...

of specimens became a passion of scientific gentlemen and a lucrative enterprise for entrepreneurs; many naturalists traveled the globe in search of scientific knowledge and adventure. 1655 - Frontispiece of Museum Wormiani Historia

1655 - Frontispiece of Museum Wormiani Historia

Extending the work of Vesalius into experiments on still living bodies (of both humans and animals), William Harvey and other natural philosophers investigated the roles of blood, veins and arteries. Harvey's ''

De motu cordis ''Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus'' (Latin, 'An Anatomical Exercise on the Motion of the Heart and Blood in Living Beings'), commonly called ''De Motu Cordis'', is the best-known work of the physician William Harv ...

'' in 1628 was the beginning of the end for Galenic theory, and alongside

Santorio Santorio Santorio Santori (29 March, 1561 – 25 February, 1636) also called Santorio Santorio, Santorio de' Sanctoriis, or Sanctorius of Padua and various combinations of these names, was an Italian physiologist, physician, and professor, who introduc ...

's studies of metabolism, it served as an influential model of quantitative approaches to physiology. In the early 17th century, the micro-world of biology was just beginning to open up. A few lensmakers and natural philosophers had been creating crude

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

s since the late 16th century, and

Robert Hooke Robert Hooke FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using a compound microscope that ...

published the seminal '' Micrographia'' based on observations with his own compound microscope in 1665. But it was not until

Antonie van Leeuwenhoek Antonie Philips van Leeuwenhoek ( ; ; 24 October 1632 – 26 August 1723) was a Dutch microbiologist and microscopist in the Golden Age of Dutch science and technology. A largely self-taught man in science, he is commonly known as " the ...

's dramatic improvements in lensmaking beginning in the 1670s—ultimately producing up to 200-fold magnification with a single lens—that scholars discovered

spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, ...

,

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, infusoria and the sheer strangeness and diversity of microscopic life. Similar investigations by

Jan Swammerdam Jan Swammerdam (February 12, 1637 – February 17, 1680) was a Dutch biologist and microscopist. His work on insects demonstrated that the various phases during the life of an insect—egg, larva, pupa, and adult—are different forms of the ...

led to a new interest in

entomology Entomology () is the science, scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such ...

and built the basic techniques of microscopic dissection and

staining Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the ...

.

As the microscopic world was expanding, the macroscopic world was shrinking. Botanists such as

John Ray John Ray FRS (29 November 1627 – 17 January 1705) was a Christian English naturalist widely regarded as one of the earliest of the English parson-naturalists. Until 1670, he wrote his name as John Wray. From then on, he used 'Ray', after ...

worked to incorporate the flood of newly discovered organisms shipped from across the globe into a coherent taxonomy, and a coherent theology (

natural theology Natural theology, once also termed physico-theology, is a type of theology that seeks to provide arguments for theological topics (such as the existence of a deity) based on reason and the discoveries of science. This distinguishes it from ...

). Debate over another flood, the Noachian, catalyzed the development of

paleontology Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

; in 1669 Nicholas Steno published an essay on how the remains of living organisms could be trapped in layers of sediment and mineralized to produce

fossil 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 ...

s. Although Steno's ideas about fossilization were well known and much debated among natural philosophers, an organic origin for all fossils would not be accepted by all naturalists until the end of the 18th century due to philosophical and theological debate about issues such as the age of the earth and

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

.

19th century: the emergence of biological disciplines

Up through the 19th century, the scope of biology was largely divided between medicine, which investigated questions of form and function (i.e., physiology), and natural history, which was concerned with the diversity of life and interactions among different forms of life and between life and non-life. By 1900, much of these domains overlapped, while natural history (and its counterpart

natural philosophy Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...

) had largely given way to more specialized scientific disciplines— cytology, bacteriology,

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

,

embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...

,

geography Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and ...

, and

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

.

Geographie der Pflanzen in den Tropen-Ländern

Use of the term ''biology''

The term ''biology'' in its modern sense appears to have been introduced independently by Thomas Beddoes (in 1799),

Karl Friedrich Burdach Karl Friedrich Burdach (12 June 1776 – 16 July 1847) was a German physiologist. He was born in Leipzig and died in Königsberg. He was the first to use the word "biology" and was a pioneer of neuroanatomy. Life Burdach came from a family of ...

(in 1800),

Gottfried Reinhold Treviranus Gottfried Reinhold Treviranus (4 February 1776, Bremen – 16 February 1837, Bremen) was a German physician, naturalist, and proto-evolutionary biologist. His younger brother, Ludolph Christian Treviranus (1779–1864), was also a naturalist an ...

(''Biologie oder Philosophie der lebenden Natur'', 1802) and

Jean-Baptiste Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biologi ...

(''Hydrogéologie'', 1802). The word itself appears in the title of Volume 3 of

Michael Christoph Hanow Michael Christoph Hanow (also Hanov, Hanovius) (12 December 1695, in Zamborst near Neustettin, Pomerania – 22 September 1773, in Danzig) was a German meteorologist, historian, professor of mathematics and since 1717 rector of the Academic Gym ...

's ''Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia'', published in 1766. Before ''biology,'' there were several terms used for the study of animals and plants. '' Natural history'' referred to the descriptive aspects of biology, though it also included

mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proces ...

and other non-biological fields; from the Middle Ages through the Renaissance, the unifying framework of natural history was the ''scala naturae'' or Great Chain of Being. ''

Natural philosophy Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...

'' and ''

natural theology Natural theology, once also termed physico-theology, is a type of theology that seeks to provide arguments for theological topics (such as the existence of a deity) based on reason and the discoveries of science. This distinguishes it from ...

'' encompassed the conceptual and metaphysical basis of plant and animal life, dealing with problems of why organisms exist and behave the way they do, though these subjects also included what is now

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

,

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

,

chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

, and

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 ...

. Physiology and (botanical) pharmacology were the province of medicine. ''Botany'', ''Zoology'', and (in the case of fossils) ''Geology'' replaced ''natural history'' and ''natural philosophy'' in the 18th and 19th centuries before ''biology'' was widely adopted. To this day, "botany" and "zoology" are widely used, although they have been joined by other sub-disciplines of biology.

Natural history and natural philosophy

Widespread travel by naturalists in the early-to-mid-19th century resulted in a wealth of new information about the diversity and distribution of living organisms. Of particular importance was the work of

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister, p ...

, which analyzed the relationship between organisms and their environment (i.e., the domain of natural history) using the quantitative approaches of

natural philosophy Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...

(i.e.,

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

and

chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

). Humboldt's work laid the foundations of

biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

and inspired several generations of scientists.

Geology and paleontology

The emerging discipline of geology also brought natural history and natural philosophy closer together; the establishment of the stratigraphic column linked the spatial distribution of organisms to their temporal distribution, a key precursor to concepts of evolution.

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...

and others made great strides in

comparative anatomy Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny (the evolution of species). The science began in the classical era, continuing in t ...

and

paleontology Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

in the late 1790s and early 19th century. In a series of lectures and papers that made detailed comparisons between living mammals and

fossil 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 ...

remains Cuvier was able to establish that the fossils were remains of species that had become

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

—rather than being remains of species still alive elsewhere in the world, as had been widely believed. Fossils discovered and described by Gideon Mantell, William Buckland, Mary Anning, and

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owe ...

among others helped establish that there had been an 'age of reptiles' that had preceded even the prehistoric mammals. These discoveries captured the public imagination and focused attention on the history of life on earth. Most of these geologists held to

catastrophism In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow increment ...

, but

Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...

's influential ''Principles of Geology'' (1830) popularised Hutton's uniformitarianism, a theory that explained the geological past and present on equal terms.

Evolution and biogeography

The most significant evolutionary theory before Darwin's was that of

Jean-Baptiste Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biologi ...

; based on the inheritance of acquired characteristics (an inheritance mechanism that was widely accepted until the 20th century), it described a chain of development stretching from the lowliest microbe to humans. The British naturalist

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...

, combining the biogeographical approach of Humboldt, the uniformitarian geology of Lyell,

Thomas Malthus Thomas Robert Malthus (; 13/14 February 1766 – 29 December 1834) was an English cleric, scholar and influential economist in the fields of political economy and demography. In his 1798 book '' An Essay on the Principle of Population'', Mal ...

's writings on population growth, and his own morphological expertise, created a more successful evolutionary theory based on

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 ...

; similar evidence led

Alfred Russel Wallace Alfred Russel Wallace (8 January 1823 – 7 November 1913) was a British naturalist, explorer, geographer, anthropologist, biologist and illustrator. He is best known for independently conceiving the theory of evolution through natural se ...

to independently reach the same conclusions. The 1859 publication of Darwin's theory in '' On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life'' is often considered the central event in the history of modern biology. Darwin's established credibility as a naturalist, the sober tone of the work, and most of all the sheer strength and volume of evidence presented, allowed ''Origin'' to succeed where previous evolutionary works such as the anonymous ''

Vestiges of Creation ''Vestiges of the Natural History of Creation'' is an 1844 work of speculative natural history and philosophy by Robert Chambers (publisher born 1802), Robert Chambers. Published anonymously in England, it brought together various ideas of stell ...

'' had failed. Most scientists were convinced of evolution and

common descent Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. All living beings are in fact descendants of a unique ancestor commonly referred to as the last universal comm ...

by the end of the 19th century. However, natural selection would not be accepted as the primary mechanism of evolution until well into the 20th century, as most contemporary theories of heredity seemed incompatible with the inheritance of random variation. Darwins first tree

Wallace, following on earlier work by de Candolle, Humboldt and Darwin, made major contributions to zoogeography. Because of his interest in the transmutation hypothesis, he paid particular attention to the geographical distribution of closely allied species during his field work first in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

and then in the

Malay archipelago The Malay Archipelago (Indonesian/Malay: , tgl, Kapuluang Malay) is the archipelago between mainland Indochina and Australia. It has also been called the " Malay world," "Nusantara", "East Indies", Indo-Australian Archipelago, Spices Archipe ...

. While in the archipelago he identified the Wallace line, which runs through the Spice Islands dividing the fauna of the archipelago between an Asian zone and a

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

/Australian zone. His key question, as to why the fauna of islands with such similar climates should be so different, could only be answered by considering their origin. In 1876 he wrote ''The Geographical Distribution of Animals'', which was the standard reference work for over half a century, and a sequel, ''Island Life'', in 1880 that focused on island biogeography. He extended the six-zone system developed by Philip Sclater for describing the geographical distribution of birds to animals of all kinds. His method of tabulating data on animal groups in geographic zones highlighted the discontinuities; and his appreciation of evolution allowed him to propose rational explanations, which had not been done before. The scientific study of

heredity Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic inform ...

grew rapidly in the wake of Darwin's ''Origin of Species'' with the work of

Francis Galton Sir Francis Galton, FRS FRAI (; 16 February 1822 – 17 January 1911), was an English Victorian era polymath: a statistician, sociologist, psychologist, anthropologist, tropical explorer, geographer, inventor, meteorologist, proto- ...

and the biometricians. The origin of

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

is usually traced to the 1866 work of the

monk A monk (, from el, μοναχός, ''monachos'', "single, solitary" via Latin ) is a person who practices religious asceticism by monastic living, either alone or with any number of other monks. A monk may be a person who decides to dedica ...

Gregor Mendel, who would later be credited with the

laws of inheritance Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularize ...

. However, his work was not recognized as significant until 35 years afterward. In the meantime, a variety of theories of inheritance (based on pangenesis,

orthogenesis Orthogenesis, also known as orthogenetic evolution, progressive evolution, evolutionary progress, or progressionism, is an obsolete biological hypothesis that organisms have an innate tendency to evolve in a definite direction towards some go ...

, or other mechanisms) were debated and investigated vigorously.

Embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...

and

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

also became central biological fields, especially as linked to evolution and popularized in the work of

Ernst Haeckel Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new sp ...

. Most of the 19th century work on heredity, however, was not in the realm of natural history, but that of experimental physiology.

Physiology

Over the course of the 19th century, the scope of physiology expanded greatly, from a primarily medically oriented field to a wide-ranging investigation of the physical and chemical processes of life—including plants, animals, and even microorganisms in addition to man. ''Living things as machines'' became a dominant metaphor in biological (and social) thinking. Albert Edelfelt - Louis Pasteur - 1885

Cell theory, embryology and germ theory

Advances in

microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...

also had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the cell. In 1838 and 1839,

Schleiden Schleiden is a town in North Rhine-Westphalia, Germany. It lies in the Eifel hills, in the district of Euskirchen, and has 12,998 inhabitants as of 30 June 2017. Schleiden is connected by a tourist railway to Kall, on the Eifel Railway between Col ...

and Schwann began promoting the ideas that (1) the basic unit of organisms is the cell and (2) that individual cells have all the characteristics of

life 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, energ ...

, though they opposed the idea that (3) all cells come from the division of other cells. Thanks to the work of Robert Remak and Rudolf Virchow, however, by the 1860s most biologists accepted all three tenets of what came to be known as cell theory. Cell theory led biologists to re-envision individual organisms as interdependent assemblages of individual cells. Scientists in the rising field of cytology, armed with increasingly powerful microscopes and new

staining Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the ...

methods, soon found that even single cells were far more complex than the homogeneous fluid-filled chambers described by earlier microscopists. Robert Brown had described the

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucle ...

in 1831, and by the end of the 19th century cytologists identified many of the key cell components:

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, centrosomes

mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

,

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

s, and other structures made visible through staining. Between 1874 and 1884

Walther Flemming Walther Flemming (21 April 1843 – 4 August 1905) was a German biologist and a founder of cytogenetics. He was born in Sachsenberg (now part of Schwerin) as the fifth child and only son of the psychiatrist Carl Friedrich Flemming (1799–1880) ...

described the discrete stages of mitosis, showing that they were not artifacts of staining but occurred in living cells, and moreover, that chromosomes doubled in number just before the cell divided and a daughter cell was produced. Much of the research on cell reproduction came together in August Weismann's theory of heredity: he identified the nucleus (in particular chromosomes) as the hereditary material, proposed the distinction between

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 ...

s and

germ cell Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embry ...

s (arguing that chromosome number must be halved for germ cells, a precursor to the concept of

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately resu ...

), and adopted Hugo de Vries's theory of

pangene Pangenesis was Charles Darwin's hypothetical mechanism for heredity, in which he proposed that each part of the body continually emitted its own type of small organic particles called gemmules that aggregated in the gonads, contributing heritabl ...

s. Weismannism was extremely influential, especially in the new field of experimental

embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...

. By the mid-1850s the miasma theory of disease was largely superseded by the

germ theory of disease The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to be seen without magnification, invade h ...

, creating extensive interest in microorganisms and their interactions with other forms of life. By the 1880s, bacteriology was becoming a coherent discipline, especially through the work of

Robert Koch Heinrich Hermann Robert Koch ( , ; 11 December 1843 – 27 May 1910) was a German physician and microbiologist. As the discoverer of the specific causative agents of deadly infectious diseases including tuberculosis, cholera (though the Vibrio ...

, who introduced methods for growing pure cultures on agar gels containing specific nutrients in

Petri dish A Petri dish (alternatively known as a Petri plate or cell-culture dish) is a shallow transparent lidded dish that biologists use to hold growth medium in which cells can be cultured,R. C. Dubey (2014): ''A Textbook Of Biotechnology For Class- ...

es. The long-held idea that living organisms could easily originate from nonliving matter ( spontaneous generation) was attacked in a series of experiments carried out by

Louis Pasteur Louis Pasteur (, ; 27 December 1822 – 28 September 1895) was a French chemist and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization, the latter of which was named afte ...

, while debates over

vitalism Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...

vs.

mechanism Mechanism may refer to: *Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that a ...

(a perennial issue since the time of Aristotle and the Greek atomists) continued apace.

Rise of organic chemistry and experimental physiology

In chemistry, one central issue was the distinction between organic and inorganic substances, especially in the context of organic transformations such as

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

and

putrefaction Putrefaction is the fifth stage of death, following pallor mortis, algor mortis, rigor mortis, and livor mortis. This process references the breaking down of a body of an animal, such as a human, post-mortem. In broad terms, it can be viewed ...

. Since Aristotle these had been considered essentially biological ('' vital'') processes. However,

Friedrich Wöhler Friedrich Wöhler () FRS(For) HonFRSE (31 July 180023 September 1882) was a German chemist known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form. He was the firs ...

, Justus Liebig and other pioneers of the rising field of

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

—building on the work of Lavoisier—showed that the organic world could often be analyzed by physical and chemical methods. In 1828 Wöhler showed that the organic substance

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important r ...

could be created by chemical means that do not involve life, providing a powerful challenge to

vitalism Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...

. Cell extracts ("ferments") that could effect chemical transformations were discovered, beginning with

diastase A diastase (; from Greek διάστασις, "separation") is any one of a group of enzymes that catalyses the breakdown of starch into maltose. Alpha amylase degrades starch to a mixture of the disaccharide maltose; the trisaccharide maltotriose, ...

in 1833. By the end of the 19th century the concept of

enzymes Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

was well established, though equations of

chemical kinetics Chemical kinetics, also known as reaction kinetics, is the branch of physical chemistry that is concerned with understanding the rates of chemical reactions. It is to be contrasted with chemical thermodynamics, which deals with the direction in wh ...

would not be applied to enzymatic reactions until the early 20th century. Physiologists such as Claude Bernard explored (through vivisection and other experimental methods) the chemical and physical functions of living bodies to an unprecedented degree, laying the groundwork for

endocrinology Endocrinology (from '' endocrine'' + '' -ology'') is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones. It is also concerned with the integration of developmental event ...

(a field that developed quickly after the discovery of the first

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

, secretin, in 1902), biomechanics, and the study of nutrition and digestion. The importance and diversity of experimental physiology methods, within both medicine and biology, grew dramatically over the second half of the 19th century. The control and manipulation of life processes became a central concern, and experiment was placed at the center of biological education.

Twentieth century biological sciences

At the beginning of the 20th century, biological research was largely a professional endeavour. Most work was still done in the natural history mode, which emphasized morphological and phylogenetic analysis over experiment-based causal explanations. However, anti-vitalism, vitalist experimental physiologists and embryologists, especially in Europe, were increasingly influential. The tremendous success of experimental approaches to development, heredity, and metabolism in the 1900s and 1910s demonstrated the power of experimentation in biology. In the following decades, experimental work replaced natural history as the dominant mode of research.

Ecology and environmental science

In the early 20th century, naturalists were faced with increasing pressure to add rigor and preferably experimentation to their methods, as the newly prominent laboratory-based biological disciplines had done. Ecology had emerged as a combination of biogeography with the biogeochemical cycle concept pioneered by chemists; field biologists developed quantitative methods such as the quadrat and adapted laboratory instruments and cameras for the field to further set their work apart from traditional natural history. Zoologists and botanists did what they could to mitigate the unpredictability of the living world, performing laboratory experiments and studying semi-controlled natural environments such as gardens; new institutions like the Carnegie Station for Experimental Evolution and the Marine Biological Laboratory provided more controlled environments for studying organisms through their entire life cycles. The ecological succession concept, pioneered in the 1900s and 1910s by Henry Chandler Cowles and Frederic Clements, was important in early plant ecology. Alfred Lotka's predator-prey equations, G. Evelyn Hutchinson's studies of the biogeography and biogeochemical structure of lakes and rivers (limnology) and Charles Sutherland Elton, Charles Elton's studies of animal food chains were pioneers among the succession of quantitative methods that colonized the developing ecological specialties. Ecology became an independent discipline in the 1940s and 1950s after Eugene P. Odum synthesized many of the concepts of ecosystem ecology, placing relationships between groups of organisms (especially material and energy relationships) at the center of the field. In the 1960s, as evolutionary theorists explored the possibility of multiple units of selection, ecologists turned to evolutionary approaches. In population ecology, debate over group selection was brief but vigorous; by 1970, most biologists agreed that natural selection was rarely effective above the level of individual organisms. The evolution of ecosystems, however, became a lasting research focus. Ecology expanded rapidly with the rise of the environmental movement; the International Biological Program attempted to apply the methods of big science (which had been so successful in the physical sciences) to ecosystem ecology and pressing environmental issues, while smaller-scale independent efforts such as island biogeography and the Hubbard Brook Experimental Forest helped redefine the scope of an increasingly diverse discipline.

Classical genetics, the modern synthesis, and evolutionary theory

1900 marked the so-called ''rediscovery of Mendel'': Hugo de Vries, Carl Correns, and Erich von Tschermak independently arrived at Mendel's laws (which were not actually present in Mendel's work). Soon after, cytologists (cell biologists) proposed that

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 were the hereditary material. Between 1910 and 1915, Thomas Hunt Morgan and the "Drosophilists" in his fly lab forged these two ideas—both controversial—into the "Mendelian-chromosome theory" of heredity. They quantified the phenomenon of genetic linkage and postulated that genes reside on chromosomes like beads on string; they hypothesized Chromosomal crossover, crossing over to explain linkage and constructed genetic maps of the fruit fly ''Drosophila melanogaster'', which became a widely used model organism. Hugo de Vries tried to link the new genetics with evolution; building on his work with heredity and Hybrid (biology), hybridization, he proposed a theory of mutationism, which was widely accepted in the early 20th century. Lamarckism, or the theory of inheritance of acquired characteristics also had many adherents. Darwinism was seen as incompatible with the continuously variable traits studied by biometricians, which seemed only partially heritable. In the 1920s and 1930s—following the acceptance of the Mendelian-chromosome theory— the emergence of the discipline of

population genetics Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and pop ...

, with the work of R.A. Fisher, J.B.S. Haldane and Sewall Wright, unified the idea of evolution by

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 ...

with Mendelian inheritance, Mendelian genetics, producing the Modern synthesis (20th century), modern synthesis. The inheritance of acquired characters was rejected, while mutationism gave way as genetic theories matured. In the second half of the century the ideas of population genetics began to be applied in the new discipline of the genetics of behavior, sociobiology, and, especially in humans, evolutionary psychology. In the 1960s W.D. Hamilton and others developed game theory approaches to explain altruism from an evolutionary perspective through kin selection. The possible origin of higher organisms through endosymbiosis, and contrasting approaches to molecular evolution in the gene-centered view of evolution, gene-centered view (which held selection as the predominant cause of evolution) and the neutral theory of molecular evolution, neutral theory (which made genetic drift a key factor) spawned perennial debates over the proper balance of adaptationism and contingency in evolutionary theory. In the 1970s Stephen Jay Gould and Niles Eldredge proposed the theory of punctuated equilibrium which holds that stasis is the most prominent feature of the fossil record, and that most evolutionary changes occur rapidly over relatively short periods of time. In 1980 Luis Walter Alvarez, Luis Alvarez and Walter Alvarez proposed the hypothesis that an impact event was responsible for the Cretaceous–Paleogene extinction event. Also in the early 1980s, statistical analysis of the fossil record of marine organisms published by Jack Sepkoski and David M. Raup led to a better appreciation of the importance of mass extinction events to the history of life on earth.

Biochemistry, microbiology, and molecular biology

By the end of the 19th century all of the major pathways of drug metabolism had been discovered, along with the outlines of protein and fatty acid metabolism and urea synthesis. In the early decades of the 20th century, the minor components of foods in human nutrition, the vitamins, began to be isolated and synthesized. Improved laboratory techniques such as chromatography and electrophoresis led to rapid advances in physiological chemistry, which—as ''biochemistry''—began to achieve independence from its medical origins. In the 1920s and 1930s, biochemists—led by Hans Adolf Krebs, Hans Krebs and Carl Ferdinand Cori, Carl and Gerty Cori—began to work out many of the central metabolic pathways of life: the citric acid cycle, glycogenesis and glycolysis, and the synthesis of steroids and porphyrins. Between the 1930s and 1950s, Fritz Lipmann and others established the role of Adenosine triphosphate, ATP as the universal carrier of energy in the cell, and

mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

as the powerhouse of the cell. Such traditionally biochemical work continued to be very actively pursued throughout the 20th century and into the 21st.

Origins of molecular biology

Following the rise of classical genetics, many biologists—including a new wave of physical scientists in biology—pursued the question of the gene and its physical nature. Warren Weaver—head of the science division of the Rockefeller Foundation—issued grants to promote research that applied the methods of physics and chemistry to basic biological problems, coining the term ''

molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

'' for this approach in 1938; many of the significant biological breakthroughs of the 1930s and 1940s were funded by the Rockefeller Foundation. TMV virus under magnification

Like biochemistry, the overlapping disciplines of bacteriology and virology (later combined as ''microbiology''), situated between science and medicine, developed rapidly in the early 20th century. Félix d'Herelle's isolation of bacteriophage during World War I initiated a long line of research focused on phage viruses and the bacteria they infect. The development of standard, genetically uniform organisms that could produce repeatable experimental results was essential for the development of molecular genetics. After early work with ''Drosophila'' and maize, the adoption of simpler Scientific modelling, model systems like the bread mold ''Neurospora crassa'' made it possible to connect genetics to biochemistry, most importantly with George Wells Beadle, Beadle and Edward Lawrie Tatum, Tatum's one gene-one enzyme hypothesis in 1941. Genetics experiments on even simpler systems like tobacco mosaic virus and bacteriophage, aided by the new technologies of electron microscope, electron microscopy and ultracentrifuge, ultracentrifugation, forced scientists to re-evaluate the literal meaning of ''life''; virus heredity and reproducing nucleoprotein cell structures outside the nucleus ("plasmagenes") complicated the accepted Mendelian-chromosome theory. Crick's 1958 central dogma

Oswald Avery showed in 1943 that DNA was likely the genetic material of the chromosome, not its protein; the issue was settled decisively with the 1952 Hershey–Chase experiment—one of many contributions from the so-called phage group centered around physicist-turned-biologist Max Delbrück. In 1953 James Watson and Francis Crick, building on the work of Maurice Wilkins and Rosalind Franklin, suggested that the structure of DNA was a double helix. In their famous paper "Molecular structure of Nucleic Acids", Watson and Crick noted coyly, "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material." After the 1958 Meselson–Stahl experiment confirmed the semiconservative replication of DNA, it was clear to most biologists that nucleic acid sequence must somehow determine Peptide sequence, amino acid sequence in proteins; physicist George Gamow proposed that a fixed genetic code connected proteins and DNA. Between 1953 and 1961, there were few known biological sequences—either DNA or protein—but an abundance of proposed code systems, a situation made even more complicated by expanding knowledge of the intermediate role of RNA. In 1961, it was demonstrated that when a gene encodes a protein, three sequential bases of a gene’s DNA specify each successive amino acid of the protein. Thus the genetic code is a triplet code, where each triplet (called a codon) specifies a particular amino acid. Furthermore, it was shown that the codons do not overlap with each other in the DNA sequence encoding a protein, and that each sequence is read from a fixed starting point. To actually decipher the code, it took an extensive series of experiments in biochemistry and bacterial genetics, between 1961 and 1966—most importantly the work of Marshall Warren Nirenberg, Nirenberg and Har Gobind Khorana, Khorana. During 1962-1964, numerous conditional lethal mutants of a bacterial virus were isolated. These mutants were used in several different labs to advance fundamental understanding of the functions and interactions of the proteins employed in the machinery of DNA replication, DNA repair, genetic recombination, DNA recombination, and in the assembly of molecular structures.

Expansion of molecular biology

In addition to the Division of Biology at Caltech, the Laboratory of Molecular Biology (and its precursors) at Cambridge University, Cambridge, and a handful of other institutions, the Pasteur Institute became a major center for molecular biology research in the late 1950s. Scientists at Cambridge, led by Max Perutz and John Kendrew, focused on the rapidly developing field of structural biology, combining X-ray crystallography with Molecular modelling and the new computational possibilities of History of computing hardware, digital computing (benefiting both directly and indirectly from the military funding of science). A number of biochemists led by Frederick Sanger later joined the Cambridge lab, bringing together the study of macromolecule, macromolecular structure and function. At the Pasteur Institute, François Jacob and Jacques Monod followed the 1959 Arthur Pardee#The PaJaMo experiment, PaJaMo experiment with a series of publications regarding the lac operon, ''lac'' operon that established the concept of gene regulation and identified what came to be known as messenger RNA. By the mid-1960s, the intellectual core of molecular biology—a model for the molecular basis of metabolism and reproduction— was largely complete. The late 1950s to the early 1970s was a period of intense research and institutional expansion for molecular biology, which had only recently become a somewhat coherent discipline. In what organismic biologist E. O. Wilson called "The Molecular Wars", the methods and practitioners of molecular biology spread rapidly, often coming to dominate departments and even entire disciplines. Molecularization was particularly important in

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...

, immunology,

embryology Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...

, and neurobiology, while the idea that life is controlled by a "genetic program"—a metaphor Jacob and Monod introduced from the emerging fields of cybernetics and computer science—became an influential perspective throughout biology. Immunology in particular became linked with molecular biology, with innovation flowing both ways: the clonal selection theory developed by Niels Jerne and Frank Macfarlane Burnet in the mid-1950s helped shed light on the general mechanisms of protein synthesis. Resistance to the growing influence of molecular biology was especially evident in evolutionary biology. Protein sequencing had great potential for the quantitative study of evolution (through the molecular clock hypothesis), but leading evolutionary biologists questioned the relevance of molecular biology for answering the big questions of evolutionary causation. Departments and disciplines fractured as organismic biologists asserted their importance and independence: Theodosius Dobzhansky made the famous statement that "nothing in biology makes sense except in the light of evolution" as a response to the molecular challenge. The issue became even more critical after 1968; Motoo Kimura's neutral theory of molecular evolution suggested that

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 ...

was not the ubiquitous cause of evolution, at least at the molecular level, and that molecular evolution might be a fundamentally different process from Morphology (biology), morphological evolution. (Resolving this "molecular/morphological paradox" has been a central focus of molecular evolution research since the 1960s.)

Biotechnology, genetic engineering, and genomics

Biotechnology in the general sense has been an important part of biology since the late 19th century. With the industrialization of brewing and agriculture, chemists and biologists became aware of the great potential of human-controlled biological processes. In particular, Industrial fermentation, fermentation proved a great boon to chemical industries. By the early 1970s, a wide range of biotechnologies were being developed, from drugs like penicillin and steroids to foods like ''Chlorella'' and single-cell protein to gasohol—as well as a wide range of Hybrid (biology), hybrid high-yield crops and agricultural technologies, the basis for the Green Revolution. E coli at 10000x, original

Recombinant DNA

Biotechnology in the modern sense of genetic engineering began in the 1970s, with the invention of recombinant DNA techniques. Restriction enzymes were discovered and characterized in the late 1960s, following on the heels of the isolation, then duplication, then synthesis of viral genes. Beginning with the lab of Paul Berg in 1972 (aided by ''EcoRI'' from Herbert Boyer's lab, building on work with ligase by Arthur Kornberg's lab), molecular biologists put these pieces together to produce the first transgenic organisms. Soon after, others began using plasmid Vector (molecular biology), vectors and adding genes for antibiotic resistance, greatly increasing the reach of the recombinant techniques. Wary of the potential dangers (particularly the possibility of a prolific bacteria with a viral cancer-causing gene), the scientific community as well as a wide range of scientific outsiders reacted to these developments with both enthusiasm and fearful restraint. Prominent molecular biologists led by Berg suggested a temporary moratorium on recombinant DNA research until the dangers could be assessed and policies could be created. This moratorium was largely respected, until the participants in the 1975 Asilomar Conference on Recombinant DNA created policy recommendations and concluded that the technology could be used safely. Following Asilomar, new genetic engineering techniques and applications developed rapidly. DNA sequencing methods improved greatly (pioneered by Frederick Sanger and Walter Gilbert), as did oligonucleotide synthesis and transfection techniques. Researchers learned to control the expression of transgenes, and were soon racing—in both academic and industrial contexts—to create organisms capable of expressing human genes for the production of human hormones. However, this was a more daunting task than molecular biologists had expected; developments between 1977 and 1980 showed that, due to the phenomena of split genes and splicing (genetics), splicing, higher organisms had a much more complex system of gene expression than the bacteria models of earlier studies. The first such race, for synthesizing human insulin, was won by Genentech. This marked the beginning of the biotech boom (and with it, the era of gene patents), with an unprecedented level of overlap between biology, industry, and law.

Molecular systematics and genomics

By the 1980s, protein sequencing had already transformed methods of scientific classification of organisms (especially cladistics) but biologists soon began to use RNA and DNA sequences as Trait (biology), characters; this expanded the significance of molecular evolution within evolutionary biology, as the results of molecular systematics could be compared with traditional evolutionary trees based on

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

. Following the pioneering ideas of Lynn Margulis on endosymbiotic theory, which holds that some of the organelles of eukaryotic cells originated from free living prokaryotic organisms through symbiotic relationships, even the overall division of the tree of life was revised. Into the 1990s, the five domains (Plants, Animals, Fungi, Protists, and Monerans) became three (the Archaea, the Bacteria, and the Eukarya) based on Carl Woese's pioneering molecular systematics work with 16S ribosomal RNA, 16S rRNA sequencing. The development and popularization of the polymerase chain reaction (PCR) in mid-1980s (by Kary Mullis and others at Cetus Corp.) marked another watershed in the history of modern biotechnology, greatly increasing the ease and speed of genetic analysis. Coupled with the use of expressed sequence tags, PCR led to the discovery of many more genes than could be found through traditional biochemical or genetic methods and opened the possibility of sequencing entire genomes. The unity of much of the morphogenesis of organisms from fertilized egg to adult began to be unraveled after the discovery of the homeobox genes, first in fruit flies, then in other insects and animals, including humans. These developments led to advances in the field of evolutionary developmental biology towards understanding how the various body plans of the animal phyla have evolved and how they are related to one another. The Human Genome Project—the largest, most costly single biological study ever undertaken—began in 1988 under the leadership of James D. Watson, after preliminary work with genetically simpler model organisms such as ''E. coli'', ''S. cerevisiae'' and ''Caenorhabditis elegans, C. elegans''. Shotgun sequencing and gene discovery methods pioneered by Craig Venter—and fueled by the financial promise of gene patents with Celera Genomics— led to a public–private sequencing competition that ended in compromise with the first draft of the human DNA sequence announced in 2000.Davies, ''Cracking the Genome'', Introduction; see also: Sulston, ''The Common Thread''

Twenty-first century biological sciences

At the beginning of the 21st century, biological sciences converged with previously differentiated new and classic disciplines like Physics into research fields like Biophysics. Advances were made in analytical chemistry and physics instrumentation including improved sensors, optics, tracers, instrumentation, signal processing, networks, robots, satellites, and compute power for data collection, storage, analysis, modeling, visualization, and simulations. These technological advances allowed theoretical and experimental research including internet publication of molecular biochemistry, biological systems, and ecosystems science. This enabled worldwide access to better measurements, theoretical models, complex simulations, theory predictive model experimentation, analysis, worldwide internet observational data reporting, open peer-review, collaboration, and internet publication. New fields of biological sciences research emerged including Bioinformatics, Neuroscience, Theoretical biology, Computational genomics, Astrobiology and Synthetic Biology.

References

Citations

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External links

International Society for History, Philosophy, and Social Studies of Biology
– professional history of biology organization
History of Biology
– Historyworld article
History of Biology
at Bioexplorer.Net – a collection of history of biology links
Biology
– historically oriented article on Citizendium
Miall, L. C. (1911) History of biology.
Watts & Co. London * {{DEFAULTSORT:History Of Biology History of biology, Articles containing video clips

Prehistoric times

Earliest roots

Ancient Egypt

Mesopotamia

Separate developments in China and India

Classical antiquity

Middle Ages

Renaissance

Age of Enlightenment

19th century: the emergence of biological disciplines

Use of the term ''biology''

Natural history and natural philosophy

Geology and paleontology

Evolution and biogeography

Physiology

Cell theory, embryology and germ theory

Rise of organic chemistry and experimental physiology

Twentieth century biological sciences

Ecology and environmental science

Classical genetics, the modern synthesis, and evolutionary theory

Biochemistry, microbiology, and molecular biology

Origins of molecular biology

Expansion of molecular biology

Biotechnology, genetic engineering, and genomics

Recombinant DNA

Molecular systematics and genomics

Twenty-first century biological sciences

See also

References

Citations

Sources

External links