History of Biology Timeline

Harvey's De motu cordis in 1628 was the beginning of the end for Galenic theory, and alongside Santorio Santorio's studies of metabolism, it served as an influential model of quantitative approaches to physiology.

Image source: Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus

In 1828 Wöhler showed that the organic substance urea could be created by chemical means that do not involve life, providing a powerful challenge to vitalism.

Image source: Friedrich Wöhler

Robert Brown described the nucleus in 1831, a key discovery in the emerging science of cytology that would eventually reveal many of the cell's central components.

Image source: Robert Brown (botanist, born 1773)

Cell extracts ('ferments') that could effect chemical transformations were discovered, beginning with diastase in 1833. By the end of the 19th century the concept of enzymes was well established.

In 1838 and 1839, Schleiden and Schwann began promoting the ideas that the basic unit of organisms is the cell and that individual cells have all the characteristics of life, though they opposed the idea that all cells come from the division of other cells.

Image source: Cell theory

Physiologists such as Claude Bernard explored the chemical and physical functions of living bodies to an unprecedented degree, laying the groundwork for endocrinology, biomechanics, and the study of nutrition and digestion. The importance of experimental physiology grew dramatically over the second half of the 19th century.

Image source: Claude Bernard

Between 1874 and 1884 Walther Flemming described the discrete stages of mitosis, showing that they occurred in living cells, and that chromosomes doubled in number just before the cell divided and a daughter cell was produced.

Image source: Walther Flemming

Endocrinology developed quickly after the discovery of the first hormone, secretin, in 1902, building on the experimental physiology work of Claude Bernard and others.

Image source: Secretin

In 1669 Nicholas Steno published an essay explaining how the remains of living organisms could be trapped in layers of sediment and mineralized to produce fossils, catalyzing the development of paleontology amid debate over the Noachian flood.

Image source: Nicolas Steno

Carl Linnaeus published a basic taxonomy 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.

Image source: Carl Linnaeus

While Linnaeus conceived of species as unchanging parts of a designed hierarchy, Georges-Louis Leclerc, Comte de Buffon, treated species as artificial categories and living forms as malleable—even suggesting the possibility of common descent.

Image source: Georges-Louis Leclerc, Comte de Buffon

The compound 'biology' appears in the title of Volume 3 of Michael Christoph Hanow's Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia, published in 1766.

Image source: History of biology

Georges Cuvier and others made great strides in comparative anatomy and paleontology in the late 1790s and early 19th century, aided by widespread travel by naturalists that yielded a wealth of new information about the diversity and distribution of living organisms.

Image source: Georges Cuvier

The term biology in its modern sense was introduced independently by Thomas Beddoes (1799), Karl Friedrich Burdach (1800), Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur, 1802) and Jean-Baptiste Lamarck (Hydrogéologie, 1802).

The most significant evolutionary theory before Darwin's was that of Jean-Baptiste Lamarck; based on the inheritance of acquired characteristics, it described a chain of development stretching from the lowliest microbe to humans.

Image source: Jean-Baptiste Lamarck

Charles Lyell's influential Principles of Geology (1830) popularised Hutton's uniformitarianism, a theory that explained the geological past and present on equal terms, in contrast to the catastrophism held by most geologists of the era.

Image source: Principles of Geology

The 1859 publication of Darwin's On the Origin of Species by Means of Natural Selection is often considered the central event in the history of modern biology. Most scientists were convinced of evolution and common descent by the end of the 19th century, though natural selection was not accepted as the primary mechanism until well into the 20th century.

Image source: On the Origin of Species

In 1876 Alfred Russel Wallace wrote The Geographical Distribution of Animals, the standard reference work for over half a century, followed by Island Life in 1880, which focused on island biogeography.

Image source: Alfred Russel Wallace

Motoo Kimura's neutral theory of molecular evolution suggested that 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.

Image source: Neutral theory of molecular evolution

In 1980 Luis Alvarez and Walter Alvarez proposed the hypothesis that an impact event was responsible for the Cretaceous–Paleogene extinction event, reshaping thinking about mass extinctions.

Image source: Alvarez hypothesis

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.

Image source: Gregor Mendel

1900 marked the so-called rediscovery of Mendel by Carl Correns, who arrived at Mendel's laws, leading to the rapid development of genetics and the 'Mendelian-chromosome theory' of heredity taken up between 1910 and 1915.

Image source: Mendelian inheritance

Hugo de Vries tried to link the new genetics with evolution; building on his work with heredity and hybridization, he proposed a theory of mutationism, which was widely accepted in the early 20th century.

Image source: Mutationism

In the early 20th century, the rediscovery of Mendel's work led to the rapid development of genetics applied to fruit flies by Thomas Hunt Morgan and his students, and by the 1930s the combination of population genetics and natural selection produced the 'neo-Darwinian synthesis'.

Image source: Thomas Hunt Morgan

Warren Weaver, head of the science division of the Rockefeller Foundation, issued grants to promote research applying the methods of physics and chemistry to basic biological problems, coining the term molecular biology in 1938.

Image source: Molecular biology

After early work with Drosophila and maize, 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.

Image source: One gene–one enzyme hypothesis

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 from the phage group around Max Delbrück.

Image source: Avery–MacLeod–McCarty experiment

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. The 1958 Meselson–Stahl experiment confirmed semiconservative replication, and Gamow proposed that a fixed genetic code connected proteins and DNA.

Image source: Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid

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.

Image source: Lac operon

In 1961 it was demonstrated that three sequential bases of a gene's DNA specify each successive amino acid of a protein. To actually decipher the code took an extensive series of experiments between 1961 and 1966, most importantly the work of Nirenberg and Khorana.

Image source: Genetic code

Beginning with the lab of Paul Berg in 1972, aided by EcoRI from Herbert Boyer's lab and building on work with ligase by Arthur Kornberg's lab, molecular biologists put the pieces together to produce the first transgenic organisms.

Image source: Recombinant DNA

A voluntary moratorium on recombinant DNA research was largely respected, until the participants in the 1975 Asilomar Conference created policy recommendations and concluded that the technology could be used safely.

Image source: Asilomar Conference on Recombinant DNA

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.

Image source: RNA splicing

The Human Genome Project—the largest, most costly single biological study ever undertaken—began in 1988 under the leadership of James D. Watson, aiming to sequence the entire human genome.

Image source: Human Genome Project

By the late 20th century, new fields like genomics and proteomics reversed the trend of specialization, with organismal biologists using molecular techniques, and molecular and cell biologists investigating the interplay between genes and the environment.

Image source: Genomics

Shotgun sequencing and gene discovery methods pioneered by Craig Venter, 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.

At the beginning of the 21st century, biological sciences converged with previously differentiated new and classic disciplines like physics into research fields like biophysics.

Image source: Biophysics