c. 200 B.C. - Sushruta - wrote Sushruta Samhita describing over 120 surgical instruments, 300 surgical procedures and classified human surgery in 8 categories. Performed cosmetic surgery.
c. 400 B.C. - Xenophanes examined fossils and speculated on the evolution of life.
c.700 B.C. - Aristotle attempted a comprehensive classification of animals. His written works include Historion Animalium, a general biology of animals, De Partibus Animalium, a comparative anatomy and physiology of animals, and De Generatione Animalium, on developmental biology.
c. 600 BC - Theophrastos (or Theophrastus) begins the systematic study of botany.
c. 900 B.C. - Herophilos dissected the human body.
c. 100 B.C. - Diocles wrote the last known anatomy book and was the first to use the term anatomy.
c. 50-70 - Historia Naturalis by Pliny the Elder (Gaius Plinius Secundus) was published in 37 volumes.
130-200 - Claudius Galen wrote numerous treatises on human anatomy.
c. 1010 - Avicenna (Ibn Sina or Abu Ali al Hussein ibn Abdallah) published his Canon of Medicine (Kitab al-Qanun fi al-tibb).
1663 - Robert Hooke sees cells in cork using a microscope.
1668 - Francesco Redi disproves spontaneous generation by showing that fly maggots only appear on pieces of meat in jars if the jars are open to the air. Jars covered with cheesecloth contained no flies.
1672 - Marcello Malpighi publishes the first description of chick development, including the formation of muscle somites, circulation, and nervous system.
1683 - Anton van Leeuwenhoek observes bacteria. Leeuwenhoek's discoveries renew the question of spontaneous generation in microorganisms.
1767 - Kaspar Friedrich Wolff argues that the tissues of a developing chick form from nothing and are not simply elaborations of already-present structures in the egg.
1768 - Lazzaro Spallanzani again disproves spontaneous generation by showing that no organisms grow in a rich broth if it is first heated (to kill any organisms) and allowed to cool in a stoppered flask. He also shows that fertilization in mammals requires an egg and semen.
1771 - Joseph Priestley demonstrates that plants produce a gas that animals and flames consume. Those two gases are carbon dioxide and oxygen.
1798 - Thomas Malthus discusses human population growth and food production in An Essay on the Principle of Population.
1802 - The term biology in its modern sense is propounded independently by Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur) and Lamarck (Hydrogéologie). The word had been coined in 1800 by Karl Friedrich Burdach.
1809 - Lamarck proposes a modern theory of evolution based on the inheritance of acquired characteristics.
1817 - Pierre-Joseph Pelletier and Joseph-Bienaime Caventou isolate chlorophyll.
1820 - Christian Friedrich Nasse formulates Nasse's law: hemophilia occurs only in males and is passed on by unaffected females.
1824 - J. L Prevost and J. B. Dumas showed that the sperm in semen were not parasites, as previously thought, but, instead, the agents of fertilization.
1826 - Karl von Baer shows that the eggs of mammals are in the ovaries, ending a 200-year search for the mammalian egg.
1828 - Friedrich Woehler synthesizes urea; first synthesis of an organic compound from inorganic starting materials.
1858 - Rudolf Virchow proposes that cells can only arise from pre-existing cells; "Omnis cellula e celulla," all cell from cells. The Cell Theory states that all organisms are composed of cells (Schleiden and Schwann), and cells can only come from other cells (Virchow).
1864 - Louis Pasteur disproves the spontaneous generation of cellular life.
1865 - Gregor Mendel demonstrates in pea plants that inheritance follows definite rules. The Principle of Segregation states that each organism has two genes per trait, which segregate when the organism makes eggs or sperm. The Principle of Independent Assortment states that each gene in a pair is distributed independently during the formation of eggs or sperm. Mendel's trailblazing foundation for the science of genetics went unnoticed, to his lasting disappointment.
1865 - Friedrich August Kekulé von Stradonitz realizes that benzene is composed of carbon and hydrogen atoms in a hexagonal ring.
1874 - Jacobus van 't Hoff and Joseph-Achille Le Bel advance a three-dimensional stereochemical representation of organic molecules and propose a tetrahedral carbon atom.
1876 - Oskar Hertwig and Hermann Fol independently describe (in sea urchin eggs) the entry of sperm into the egg and the subsequent fusion of the egg and sperm nuclei to form a single new nucleus.
1884 - Emil Fischer begins his detailed analysis of the compositions and structures of sugars.
1892 - Hans Driesch separates the individual cells of a 2-cell sea urchin embryo and shows that each cell develops into a complete individual, thus disproving the theory of preformation and showing that each cell is "totipotent," containing all the hereditary information necessary to form an individual.
1937 - In Genetics and the Origin of Species, Theodosius Dobzhansky applies the chromosome theory and population genetics to natural populations in the first mature work of neo-Darwinism, also called the modern synthesis, a term coined by Julian Huxley.
1938 - A living coelacanth is found off the coast of southern Africa.
1940 - Donald Griffin and Robert Galambos announce their discovery of sonar echolocation by bats.
1942 - Max Delbruck and Salvador Luria demonstrate that bacterial resistance to virus infection is caused by random mutation and not adaptive change.
1952 - American developmental biologists Robert Briggs and Thomas King clone the first vertebrate by transplanting nuclei from leopard frogs embryos into enucleated eggs. More differentiated cells were the less able they are to direct development in the enucleated egg.
1952 - Fred Sanger, Hans Tuppy, and Ted Thompson complete their chromatographic analysis of the insulin amino acid sequence.
1952 - Rosalind Franklin concludes that DNA is a double helix with a diameter of 2 nm and the sugar-phosphate backbones on the outside of the helix, based on x ray diffraction studies. She suspects the two sugar-phosphate backbones have a peculiar relationship to each other.
1953 - After examining Franklin's unpublished data, James D. Watson and Francis Crick publish a double-helix structure for DNA, with one sugar-phosphate backbone running in the opposite direction to the other. They further suggest a mechanism by which the molecule can replicate itself and serve to transmit genetic information. Their paper, combined with the Hershey-Chase experiment and Chargaff's data on nucleotides, finally persuades biologists that DNA is the genetic material, not protein.
1960 - Four separate researchers (S. Weiss, J. Hurwitz, Audrey Stevens and J. Bonner) discover bacterial RNA polymerase, which polymerizes nucleotides under the direction of DNA.
1960 - Juan Oro finds that concentrated solutions of ammonium cyanide in water can produce the nucleotide organic base adenine.
1960 - Robert Woodward synthesizes chlorophyll.
1961 - German plant physiologist H. J. Matthaei cracks the first codon of the genetic code (the codon for the amino acid phenylalanine) using Grunberg-Manago's enzyme system for making polynucleotides.
1972 - Albert Eschenmoser and Robert Woodward synthesize vitamin B-12.
1972 - Stephen Jay Gould and Niles Eldredge propose an idea they call "punctuated equilibrium," which states that the fossil record is an accurate depiction of the pace of evolution, with long periods of "stasis" (little change) punctuated by brief periods of rapid change and species formation (within a lineage).
1972 - SJ Singer and GL Nicholson develop the fluid mosaic model, which deals with the make-up of the membrane of all cells.
1974 - Manfred Eigen and Manfred Sumper show that mixtures of nucleotide monomers and RNA replicase will give rise to RNA molecules which replicate, mutate, and evolve.
1974 - Leslie Orgel shows that RNA can replicate without RNA-replicase and that zinc aids this replication.
1977 - John Corliss, Jack Dymond, Louis Gordon, John Edmond, Richard von Herzen, Robert Ballard, Kenneth Green, David Williams, Arnold Bainbridge, Kathy Crane, and Tjeerd van Andel discover chemosynthetically based animal communities located around submarine hydrothermal vents on the Galapagos Rift.
History of science • History of medicine • Philosophy of biology • Timeline of biology and organic chemistry • Natural philosophy • Natural theology • Humboldtian science • Relationship between religion and science • Eugenics • Human Genome Project • Darwin Day • History of creationism • History of the creation-evolution controversy