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The history of biology traces human study of the living world from ancient to modern times. Although the concept of biology as a single coherent field arose in the 19th century, the biological sciences emerged from traditions of medicine and natural history reaching back to Galen and Aristotle in ancient Greece. During the Renaissance and Age of Discovery, biological thought was revolutionized by a renewed interest in empiricism and the discovery of many novel organisms. Prominent in this movement were Vesalius, who used experimentation and careful observation in physiology, and naturalists such as Linnaeus and Buffon who began to classify the diversity of life and the fossil record, as well as the development and behavior of organisms. The growing importance of natural theology was partly a response to the rise of mechanical philosophy and encouraged the growth of natural history (though it entrenched the argument from design).

In the 18th century through to the late 1800s, biological sciences such as botany and zoology became increasingly professional scientific disciplines. Lavoisier and other physical scientists began to connect the animate and inanimate worlds through physics and chemistry. Into the 19th century, explorer-naturalists such as Alexander von Humboldt investigated the interaction between organisms and their environment, and the ways this depends on geography—laying the foundations for biogeography, ecology and ethology. Naturalists began to reject essentialism and consider the importance of extinction and the mutability of species. These developments, as well as the results from embryology and paleontology, were synthesized in Charles Darwin's theory of evolution by natural selection. The end of the 19th century saw the disproof of spontaneous generation and the rise of the germ theory of disease and cytology, microbiology and physiological chemistry, though the mechanism of inheritance remained a mystery.

In the early 20th century, the rediscovery of Mendel's work led to the rapid development of genetics by Thomas Hunt Morgan and his students, and by the 1930s the combination of population genetics and natural selection in the "neo-Darwinian synthesis" and evolutionary biology. New disciplines developed rapidly, especially after Watson and Crick discovered the structure of DNA. Following the establishment of the Central Dogma and the cracking of the genetic code, biology was largely split between organismal biology—ecology, ethology, systematics, paleontology, evolutionary biology, developmental biology, and other disciplines that deal with whole organisms—and the disciplines related to molecular biology—including cell biology, biophysics, biochemistry, neuroscience and immunology. By the late 20th century, new fields like genomics and proteomics 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.

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Etymology

The word biology is formed by combining the Greek βίος (bios), meaning "life", and the suffix '-logy', meaning "science of", "knowledge of", "study of", based on the Greek verb λεγειν, 'legein' = "to select", "to gather" (cf. the noun λόγος, 'logos' = "word"). The term "biology" in its modern sense appears to have been introduced independently by Karl Friedrich Burdach (in 1800), Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur, 1802) and Jean-Baptiste Lamarck (Hydrogéologie, 1802). The word itself appears in the title of Volume 3 of Michael Christoph Hanov's Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia, published in 1766.

Before biology, there were several terms used for study of animals and plants. Natural history referred to the descriptive aspects of biology, though it also included mineralogy 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 and natural theology encompassed the conceptual 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, physics, chemistry, and astronomy. 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 century before biology was widely adopted.

Ancient and medieval knowledge

Biological knowledge in early cultures

The earliest humans must have had and passed on knowledge about plants and animals 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 about 10,000 years ago. Humans first domesticated plants for farming, then livestock animals to accompany the resulting sedentary societies.

The ancient cultures of Mesopotamia, Egypt, the Indian subcontinent, and China (among others) had sophisticated systems of philosophical, religious, and technical knowledge that encompassed the living world, and creation myths often centered on some aspect of life. However, the interwoven path of biological thinking and investigation in the Western tradition is usually traced back to secular tradition of ancient Greek philosophy.

Ancient Greek biological traditions

The Pre-Socratic philosophers 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 and his followers, especially humorism, had a lasting impact.

The philosopher Aristotle was the most influential scholar of the living world from antiquity. Though his early natural philosophy work was speculative, Aristotle's later biological writings demonstrate great concern for empiricism, biological causation, and the diversity of life. He made countless observations of nature, especially the habits and attributes of plants and animals in the world around him, which he devoted considerable attention to categorizing. In all, Aristotle classified 540 animal species, and dissected at least 50; he believed that intellectual purposes, formal causes, guided all natural processes.

Aristotle, and nearly all scholars after him until the 18th century, believed that creatures were arranged in a graded scale of perfection rising from plants on up to man: the scala naturae or Great Chain of Being. Aristotle's successor at the Lyceum, Theophrastus, 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. Many of Theophrastus' names survive into modern times, such as carpos for fruit, and pericarpion for seed vessel. Pliny the Elder was also known for his knowledge of plants and nature, and was the most prolific compiler of zoological descriptions.

A few scholars in Hellenistic period under the Ptolemies—particularly Herophilus of Chalcedon and Erasistratus of Chios—amended Aristotle's physiological work, even performing experimental dissections and vivisections. Claudius Galen became the most important authority for medicine and anatomy. Though a few ancient atomists such as Lucretius challenged the teleological viewpoint of Aristotelian ideas about life, teleology (and after the rise of Christianity, natural theology) would remain central to biological thought essentially until the 18th and 19th centuries. In the words of Ernst Mayr, "Nothing of any real consequence 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.

Medieval knowledge

The decline of the Roman Empire led to the disappearance or destruction of much knowledge. However, some people who dealt with medical issues still studied plants and animals as well. In Byzantium and the Islamic world, many of the Greek works were translated into Arabic and many of the works of Aristotle were preserved. During the High Middle Ages, a few European scholars such as Hildegard of Bingen, Albertus Magnus, and Frederick II expanded the natural history canon. The rise of European universities, though important for the development of physics and philosophy, had little impact on biological scholarship.

The Renaissance

The European Renaissance 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 treatise De humani corporis fabrica, which was based dissection of corpses. Vesalius was the first in a series of anatomists who gradually replaced scholasticism with empiricism in physiology and medicine. Via herbalism, medicine was also indirectly the source of renewed empiricism in the study of plants. Otto Brunfels, Hieronymus Bock and Leonhart Fuchs wrote extensively on wild plants, the beginning of a nature-based approach to the full range of plant life. Bestiaries 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 and Leonardo da Vinci, 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 and natural magic, especially in the work of Paracelsus, 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. This was part of a larger transition in world views that continued into the 17th century, as the traditional metaphor of nature as organism was replaced, with the rise of the mechanical philosophy, by the nature as machine metaphor.

Seventeenth and eighteenth century developments

Extending the work of Vesalius into experiments on still living bodies (of both humans and animals), Girolamo Fabrici and his student William Harvey investigated the roles of blood, veins and arteries; Harvey's De motu cordis in 1628 was the beginning of the end for Galenic theory, and 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 creating crude microscopes since the late 16th century, and Robert Hooke published the seminal Micrographia based on observations with his own compound microscope in 1665. But it was not until Antony van Leeuwenhoek's dramatic improvements in lensmaking beginning in the 1670s—ultimately producing up to 200-fold magnification with a single lens—that scholars discovered spermatozoa, bacteria, infusoria and the sheer strangeness and diversity of microscopic life. Similar investigations by Jan Swammerdam led to new interest in entomology and built the basic techniques of microscopic dissection and staining.

As the microscopic world was expanding, the macroscopic world was shrinking. Botanists such as John Ray worked to incorporate the flood of newly discovered organism shipped from across the globe into a coherent taxonomy, and a coherent theology (natural theology). Debate over another flood catalyzed the development of paleontology; 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 fossils. 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, the role of the Noachian flood, and extinction.

Systematizing, naming and classifying dominated natural history throughout much of the 17th and 18th centuries. Carolus Linnaeus published a basic taxonomy for the natural world in 1735, and in the 1750s introduced scientific names for all his species. The discovery and description of new species and collecting specimens became a widespread passion of scientific gentlemen.

Nineteenth century: the emergence of biological disciplines

Up through the nineteenth 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 (and its counterpart natural philosophy) had largely given way to more specialized scientific disciplines—cytology, bacteriology, morphology, embryology, geography, and geology.

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.

Cell theory and germ theory

Advances in microscopy also had a profound impact on biological thinking: in 1839, Schleiden and Schwann proposed the cell theory—that the basic unit of organisms is the cell and all cells come from preexisting cells. The cytologist Walther Flemming in 1882 was the first to demonstrate that the discrete stages of mitosis were not an artifact 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. In 1887 August Weismann proposed that the chromosome number must then be halved in the case of the sexual cells, the gametes. This was shortly proved to be the case and the process of meiosis began to be understood.

By the mid 1850s the miasma theory of disease was largely superseded by the germ theory of disease, 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, who introduced methods for growing pure cultures on agar gels containing specific nutrients in Petri dishes. 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, while debates over vitalism vs. mechanism continued apace.

Rise of organic chemistry and experimental physiology

One central issue was the distinction between organic and inorganic substances, especially in the context of organic transformations such as fermentation and putrefaction. Since Aristotle these had been considered essentially biological (vital) processes. However, Friedrich Wöhler, Justus Liebig and other pioneers of the rising field of organic chemistry—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 could be created by chemical means that do not involve life, providing a powerful argument against vitalism. Cell extracts ("ferments") that could effect chemical transformations were discovered, beginning with diastase in 1833, and by the end of the 19th century the concept of enzymes and the basics of chemical kinetics were well-established.

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 (a field that developed quickly after the discover of the first hormone, 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.

Natural history and natural philosophy

Widespread travel by naturalists in the early- to mid-nineteenth 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, which analyzed the relationship between organisms and their environment (i.e., the domain of natural history) using the quantitative approaches of natural philosophy (i.e., physics and chemistry). Humboldt's work laid the foundations of biogeography 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 spacial distribution of organisms to their temporal distribution, a key precursor to concepts of evolution. Georges Cuvier and others made great strides in comparative anatomy and paleontology in the late 1790s and early 1800s. In a series of lectures and papers that made detailed comparisons between living mammals and fossil remains Cuvier was able to establish that the fossils were remains of species that had become extinct—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 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, but Charles Lyell's influential Principles of Geology (1830) introduced uniformitarianism, a theory that explained the geological past and present on equal terms.

Evolution and biogeography

The first to propose an evolutionary theory was Jean-Baptiste Lamarck; 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, combining the biogeographical approach of Humboldt, the uniformitarian geology of Lyell, Thomas Malthus's writings on population growth, and his own morphological expertise, created a more successful evolutionary theory based on natural selection; similar evidence lead Alfred Russel Wallace to independently reach the same conclusions. Though natural selection would not be accepted as the primary mechanism of evolution until well into the 20th century, most scientists were convinced of evolution and common descent by the end of the 19th century.

Wallace, building on earlier work by Humbolt and Darwin, made major contributions to biogeography by focusing on the distribution of closely allied species with particular attention to the effects of geographical barriers during his research in the Amazon basin and the Malay archipelago. He discovered the Wallace line dividing the fauna of the Malay archipelago between a zone allied with Asia and a zone allied with Australia. The orinthologist Philip Sclater, drawing on the work of Wallace and others, proposed a system of 6 major geographical regions to describe the distribution of bird species in the world. Wallace and others would in turn extend Sclater's system from birds to animals of all kinds.

Heredity and development

The scientific study of heredity grew rapidly in the wake of Darwin's On the Origin of Species (1859) with the work of Francis Galton and the biometricians. The origin of genetics is usually traced to the 1866 work of the monk Gregor Mendel, who would later be credited with the laws of inheritance. 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, or other mechanisms) were debated and investigated vigorously. Embryology and ecology also became central biological fields, especially as linked to evolution and popularized in the work of Ernst Haeckel.

Twentieth century biological sciences

At the beginning of the 20th century, biological research was largely a professional endeavour. However, most work was still in the natural history mode, which emphasized morhphological and phylogenetic analysis over experiment-based causal explanations. However, anti-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.

Classical genetics and evolutionary synthesis

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 proposed that chromosomes were the hereditary material. Between 1910 and 1915, Thomas Hunt Morgan and 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 crossing over to explain linkage and constructed genetic maps of the fruit fly Drosophila melanogaster, which became a widely used model organism.

Building on his work on heredity and hybridization, Hugo de Vries proposed a mutation theory of evolution, which was widely accepted in the early 20th century. Lamarckism 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—a unification of the idea of evolution by natural selection with Mendelian genetics produced the modern synthesis; inheritance of acquired characters was rejected, while mutationism gave way as genetic theories matured. These ideas continued to be developed in the discipline of population genetics..

Further developments in evolutionary theory

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. A major step came in 1964 when W.D. Hamilton proposed Hamilton's rule a simple mathematical equation describing how the sterile workers in social insects and other forms of altruism could have evolved through kin selection. In the 1980's Hamilton would propose the important, but still controversial Red Queen hypothesis that sexual reproduction evolved to increase genetic diversity as means of countering the rapid evolution of parasites. The work of Hamilton would be elaborated by George C. Williams and Richard Dawkins into the influential but very controversial gene-centered view of evolution. In the 1970s Stephen Jay Gould and Niles Eldredge would propose the theory of punctuated equilibrium which holds that the fossil record shows that most species are evolutionarily stable for long periods of time with most evolutionary changes occuring rapidly over short periods of time when new species originate.

Ecology, ethology, and environmental science

In the early 20th century, naturalists were faced with increasing pressure to professionalize and 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; 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. G. Evelyn Hutchinson's studies of the biogeography and biogeochemical structure of lakes and rivers (limnology) and Charles Elton's studies of animal food chains set the pace for the kinds of quantitative methods that spread to 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.

Microbiology, biochemistry, 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 twentieth century, the minor components of foods in human nutrition, the vitamins, began to be isolated and synthesized. In the 1920s and 1930s, biochemists—led by 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 ATP as the universal carrier of energy in the cell, and mitochondria 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 for this approach in 1938; many of the significant biological breakthroughs of the 1930s and 1940s were funded by the Rockefeller Foundation. The adoption of simpler model systems like the bread mold Neurospora crassa made it possible to connect genetics to biochemistry, most importantly with Beadle and Tatum's "one gene, one enzyme" hypothesis in 1941. Research on even simpler systems like tobacco mosaic virus and bacteriophage, aided by the new technologies of electron microscopy and 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.

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 contribution from the so-called phage group centered around physicist-turned-biologist Max Delbrück. By 1953 James D. Watson and Francis Crick showed that the structure of DNA was a double helix and showed its probable connection to replication. It was clear to many biologists that DNA sequence must somehow determine 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. 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 Nirenberg and Khorana.

Expansion of molecular biology

In addition to the Division of Biology at Caltech, the Laboratory of Molecular Biology (and its precursors) at 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 digital computing (benefiting both directly and indirectly from the military funding of science). A number of biochemists led by Fred Sanger later joined the Cambridge lab, bringing together the study of macromolecular structure and function. At the Pasteur Institute, François Jacob and Jacques Monod followed the 1959 PaJaMo experiment with a series of publications regarding the 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, immunology, embryology, 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 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 natural selection was not the ubiquitous cause of evolution, at least at the molecular level, and that molecular evolution might be a fundamentally different process from morphological evolution. (Resolving this "molecular/morphological paradox" has been a central focus of molecular evolution research since the 1960s.)

In 1965 it was shown that normal cells in culture divide only a fixed number of times (the Hayflick Limit) then aged and died. About the same time, stem cells were shown to be exceptions to this rule and began to be studied in earnest. Toward the end of the century, totipotent stem cells came to be recognized as crucial for the understanding of developmental biology and raised hopes for new medical applications. In 1983 the unity of much of the morphogenesis of organisms from fertilized egg to adult began to be unraveled by the discovery of the homeobox genes, first in fruit flies, then in other insects and animals, including humans, and the field of evolutionary developmental biology has continued to advance.

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, 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 high-yield crops and agricultural technologies, the basis for the Green Revolution.

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 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 Fred 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, 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 characters, expanding the significance of molecular evolution within evolutionary biology. Following the pioneering ideas of Lynn Margulis on endosymbiotic theory, which holds that some of the organelles of eukaryotic cells originated as 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 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 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 C. elegans. Shotgun sequencing and gene discovery methods pioneered by Craig Venter—and fueled by the financial promise 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. By that year, the first genome of a plant model organism, Arabidopsis thaliana was also sequenced, along with the mouse and dozens of bacteria. Often these genome projects were carried by large international collaborations, a system that continues to be employed.

Recent developments

Starting in 1990 an important mechanism of gene regulation, RNA interference began to be understood and became an important laboratory technique to knockdown genes in order to determine their function in model organisms. In 2006 a large international consortium began a collaborative effort to enable researchers to conveniently obtain mice that have any one of its approximately 20,000 genes knocked out. The first decade of the twenty-first century also saw the rise of proteomics, computational biology and bioinformatics, with an emphasis on huge databases of experimentally derived data, all connected by the Internet and available to researchers everywhere.

See also

• Timeline of biology and organic chemistry
• Eugenics
• History of agricultural science
• History of anatomy
• History of immunology
• History of medicine
• History of phycology
• History of zoology (before Darwin)
• History of zoology, post-Darwin
• Molecular structure of Nucleic Acids - article published by James D. Watson and Francis Crick in 1953
• Natural history

Notes

1. On the difficulties of writing a coherent narrative of such a complex topic, see Mayr, The Growth of Biological Thought, chapter 1 ("How to write history of biology")
2. Junker Geschichte der Biologie, p 8; Coleman, Biology in the Nineteenth Century, pp 1-2
3. Mayr, The Growth of Biological Thought, pp 36-37; Coleman, Biology in the Nineteenth Century, pp 1-3
4. Magner, A History of the Life Sciences, pp 2-3
5. Magner, A History of the Life Sciences, pp 3-9
6. Magner, A History of the Life Sciences, pp 9-27
7. Mayr, The Growth of Biological Thought, pp 84-90, 135; Mason, A History of the Sciences, p 41-44
8. Mayr, The Growth of Biological Thought, pp 201-202; see also: Lovejoy, The Great Chain of Being
9. Mayr, The Growth of Biological Thought, pp 90-91; Mason, A History of the Sciences, p 46
10. Barnes, Hellenistic Philosophy and Science, p 383-384
11. Mayr, The Growth of Biological Thought, pp 90-94; quotation from p 91
12. Annas, Classical Greek Philosophy, p 252
13. Mayr, The Growth of Biological Thought, pp 91-94
14. Mayr, The Growth of Biological Thought, pp 94-95, 154-158
15. Mayr, The Growth of Biological Thought, pp 166-171
16. Magner, A History of the Life Sciences, pp 80-83
17. Magner, A History of the Life Sciences, pp 90-97
18. Merchant, The Death of Nature, chapters 1, 4, and 8
19. Magner, A History of the Life Sciences, pp 103-111
20. Magner, A History of the Life Sciences, pp 133-144
21. Mayr, The Growth of Biological Thought, pp 162-166
22. Rudwick, The Meaning of Fossils, pp 41-93
23. Mayr, The Growth of Biological Thought, chapter 4
24. Coleman, Biology in the Nineteenth Century, chapter 6; on the machine metaphor, see also: Rabinbach, The Human Motor
25. Coleman, Biology in the Nineteenth Century, chapters 2 and 3
26. Magner, A History of the Life Sciences, pp 254-276
27. Fruton, Proteins, Enzymes, Genes, chapter 4; Coleman, Biology in the Nineteenth Century, chapter 6
28. Rothman and Rothman, The Pursuit of Perfection, chapter 1; Coleman, Biology in the Nineteenth Century, chapter 7
29. Bowler, The Earth Encompassed, pp 204-211
30. Rudwick, The Meaning of Fossils, pp 112-113
31. Bowler, The Earth Encompassed, pp 211-220
32. Bowler, The Earth Encompassed, pp 237-247
33. Mayr, The Growth of Biological Thought, pp 343-357
34. Mayr, The Growth of Biological Thought, chapter 10: "Darwin's evidence for evolution and common descent"; and chapter 11: "The causation of evolution: natural selection"; Larson, Evolution, chapter 3
35. Larson, Evolution, chapter 5: "Ascent of Evolutionism"; see also: Bowler, The Eclipse of Darwinism
36. Larson, Evolution, pp 116-117
37. Mayr, The Growth of Biological Thought, pp 693-710
38. See: Coleman, Biology in the Nineteenth Century; Kohler, Landscapes and Labscapes; Allen, Life Science in the Twentieth Century
39. Randy Moore, "The 'Rediscovery' of Mendel's Work", Bioscene, Volume 27(2), May 2001.
40. T. H. Morgan, A. H. Sturtevant, H. J. Muller, C. B. Bridges (1915) The Mechanism of Mendelian Heredity Henry Holt and Company.
41. Garland Allen, Thomas Hunt Morgan: The Man and His Science (1978), chapter 5; see also: Kohler, Lords of the Fly.
42. Smocovitis, Unifying Biology, chapter 5; see also: Mayr and Provine (eds.), The Evolutionary Synthesis
43. Larson Evolution pp. 271-273
44. Larson Evolution pp. 279
45. Larson Evolution pp. 277-279
46. Larson Evolution pp. 281-283
47. Kohler, Landscapes and Lanbscapes, chapters 2, 3, 4
48. Hagen, An Engtangled Bank, chapters 2-5
49. Caldwell, "Drug metabolism and pharmacogenetics"; Fruton, Proteins, Enzymes, Genes, chapter 7
50. Fruton, Proteins, Enzymes, Genes, chapters 6 and 7
51. Morange, A History of Molecular Biology, chapter 8; Kay, The Molecular Vision of Life, Introduction, Interlude I, and Interlude II
52. Creager, The Life of a Virus, chapters 3 and 6; Morange, A History of Molecular Biology, chapter 2
53. Crick, Francis. "Central Dogma of Molecular Biology", Nature, vol. 227, pp. 561-563 (August 8, 1970)
54. Morange, A History of Molecular Biology, chapters 3, 4, 11, and 12; Fruton, Proteins, Enzymes, Genes, chapter 8
55. On Caltech molecular biology, see Kay, The Molecular Vision of Life, chapters 4-8; on the Cambridge lab, see de Chadarevian, Designs for Life; on comparisons with the Pasteur Institute, see Creager, "Building Biology across the Atlantic"
56. de Chadarevian, Designs for Life, chapters 4 and 7
57. Pardee A (2002). "PaJaMas in Paris". Trends Genet. 18 (11): 585–7. PMID 12414189.
58. Morange, A History of Molecular Biology, chapter 14
59. Wilson, Naturalist, chapter 12; Morange, A History of Molecular Biology, chapter 15
60. Morange, A History of Molecular Biology, chapter 15; Keller, The Century of the Gene, chapter 5
61. Morange, A History of Molecular Biology, pp 126-132, 213-214
62. Dietrich, "Paradox and Persuasion", pp 100-111
63. Bud, The Uses of Life, chapters 2 and 6
64. Morange, A History of Molecular Biology, chapters 15 and 16
65. Bud, The Uses of Life, chapter 8; Gottweis, Governing Molecules, chapter 3; Morange, A History of Molecular Biology, chapter 16
66. Morange, A History of Molecular Biology, chapter 16
67. Morange, A History of Molecular Biology, chapter 17
68. Krimsky, Biotechnics and Society, chapter 2; on the race for insulin, see: Hall, Invisible Frontiers; see also: Thackray (ed.), Private Science
69. Morange, A History of Molecular Biology, chapter 20; see also: Rabinow, Making PCR
70. Davies, Cracking the Genome, Introduction; see also: Sulston, The Common Thread

References

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• Allen, Garland E. Life Science in the Twentieth Century. Cambridge University Press, 1975.
• Annas, Julia Classical Greek Philosophy. In Boardman, John; Griffin, Jasper; Murray, Oswyn (ed.) The Oxford History of the Classical World. Oxford University Press: New York, 1986. ISBN 0-19-872112-9
• Barnes, Jonathan Hellenistic Philosophy and Science. In Boardman, John; Griffin, Jasper; Murray, Oswyn (ed.) The Oxford History of the Classical World. Oxford University Press: New York, 1986. ISBN 0-19-872112-9
• Bowler, Peter J. The Earth Encompassed: A History of the Environmental Sciences. W. W. Norton & Company: New York, 1992. ISBN 0-393-32080-4
• Bowler, Peter J. The Eclipse of Darwinism: Anti-Darwinian Evolution Theories in the Decades around 1900. The Johns Hopkins University Press: Baltimore, 1983. ISBN 0-8018-2932-1
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• Creager, Angela N. H. The Life of a Virus: Tobacco Mosaic Virus as an Experimental Model, 1930-1965. University of Chicago Press: Chicago, 2002. ISBN 0-226-12025-2
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• Fruton, Joseph S. Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology. Yale University Press: New Haven, 1999. ISBN 0-300-07608-8
• Gottweis, Herbert. Governing Molecules: The Discursive Politics of Genetic Engineering in Europe and the United States. MIT Press: Cambridge, MA, 1998. ISBN 0-262-07189-4
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• Hagen, Joel B. An Entangled Bank: The Origins of Ecosystem Ecology. Rutgers University Press: New Brunswick, 1992. ISBN 0-8135-1824-5
• Hall, Stephen S. Invisible Frontiers: The Race to Synthesize a Human Gene. Atlantic Monthly Press: New York, 1987. ISBN 0-87113-147-1
• Junker, Thomas. Geschichte der Biologie. C. H. Beck: München, 2004.
• Kay, Lily E. The Molecular Vision of Life: Caltech, The Rockefeller Foundation, and the Rise of the New Biology. Oxford University Press: New York, 1993. ISBN 0-19-511143-5
• Kohler, Robert E. Lords of the Fly: Drosophila Genetics and the Experimental Life. Chicago University Press: Chicago, 1994. ISBN 0-226-45063-5
• Kohler, Robert E. Landscapes and Labscapes: Exploring the Lab-Field Border in Biology. University of Chicago Press: Chicago, 2002. ISBN 0-226-45009-0
• Krimsky, Sheldon. Biotechnics and Society: The Rise of Industrial Genetics. Praeger Publishers: New York, 1991. ISBN 0-275-93860-3
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• Lovejoy, Arthur O. The Great Chain of Being: A Study of the History of an Idea. Harvard University Press, 1936. Reprinted by Harper & Row, ISBN 0-674-36150-4, 2005 paperback: ISBN 0-674-36153-9.
• Magner, Lois N. A History of the Life Sciences, third edition. Marcel Dekker, Inc.: New York, 2002. ISBN 0-8247-0824-5
• Mason, Stephen F. A History of the Sciences. Collier Books: New York, 1956.
• Mayr, Ernst. The Growth of Biological Thought: Diversity, Evolution, and Inheritance. The Belknap Press of Harvard University Press: Cambridge, Massachusetts, 1982. ISBN 0-674-36445-7
• Mayr, Ernst and William B. Provine, eds. The Evolutionary Synthesis: Perspectives on the Unification of Biology. Harvard University Press: Cambridge, 1998. ISBN 0-674-27226-9
• Morange, Michel. A History of Molecular Biology, translated by Matthew Cobb. Harvard University Press: Cambridge, 1998. ISBN 0-674-39855-6
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• Rabinow, Paul. Making PCR: A Story of Biotechnology. University of Chicago Press: Chicago, 1996. ISBN 0-226-70146-8
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• Sulston, John. The Common Thread: A Story of Science, Politics, Ethics and the Human Genome. National Academy Press, 2002. ISBN 0309084091
• Smocovitis, Vassiliki Betty. Unifying Biology: The Evolutionary Synthesis and Evolutionary Biology. Princeton University Press: Princeton, 1996. ISBN 0-691-03343-9
• Thackray, Arnold, ed. Private Science: Biotechnology and the Rise of the Molecular Sciences. University of Pennsylvania Press: Philadelphia, 1998. ISBN 0812234286
• Wilson, Edward O. Naturalist. Island Press, 1994.

External links

• International Society for History, Philosophy, and Social Studies of Biology - professional history of biology organization
• History of Biology at Bioexplorer.Net - a collection of history of biology links
• Biology: History - Google Directory

• History of biology
• Biology
• History of science