Biological research has come a long way towards understanding the nature of life. From the late 1990s our knowledge was greatly extended by the Human Genome Project, which mapped the entire genome sequences of many species, including human and chimpanzee. In the ‘postgenomic’ era, interpretation of this vast body of information in terms of protein function and metabolism (known as proteomics and metabolomics respectively) has become an important challenge, as is the understanding of organisms on the systems level (systems biology).
| c. 1500 million BC | World | The first plants, algae, appear on Earth. |
| c. 1 billion BC | World | The first fungi appear on Earth. |
| c. 570 million BC | World | The first invertebrate animals (arthropods, molluscs, and worms) appear on Earth. |
| c. 520 million BC | World | The first vertebrates appear on Earth. |
| c. 500 million BC | World | The first fish appear on Earth. |
| c. 450 million BC | World | The first lichens appear on Earth. They may have been the first form of life to live on land. |
| c. 350 million BC | World | The first land-living animals, the arthropods, appear on Earth. |
| c. 350 million BC | World | The first amphibians appear on Earth. |
| c. 300 million BC | World | The first reptiles appear on Earth. |
| c. 245 million BC | World | Many plants and animals die out in a mass extinction. It may have been caused by a huge meteorite impact. |
| c. 205 million BC–c. 65 million BC | World | Dinosaurs flourished on Earth. |
| c. 200 million BC | World | The first mammals appear on Earth. |
| c. 180 million BC | World | The first birds appear on Earth. |
| c. 65 million BC | World | The dinosaurs and many other species of plant and animal become extinct. This may have been caused by a huge meteorite impact. |
| c. 50 million BC | World | The first primates appear on Earth. |
| c. 2500000 BC | World | Homo habilis, small intelligent apes, evolve. They walk on their back legs and later learn to use tools. |
| c. 1700000 BC | World | Homo erectus evolves from Homo habilis. They learn to hunt, build huts, and use fire. |
| 1658 | Netherlands | Dutch microscopist Jan Swammerdam records oval particles in the blood of frogs – the first observation of red blood cells. |
| 1665 | England | English scientist Robert Hooke publishes Micrographia, the first serious scientific work on microscopy, describing the function of the microscope, and coining the name ‘cells’ to describe cavities he has found in the structure of cork. |
| 1674 | Netherlands | The Dutch microscopist Anton van Leeuwenhoek uses single-lens microscopes to study the composition of organisms. He discovers an extensive fauna of minute organisms, which he describes as ‘very little animalcules’. |
| 1679 | France | French Huguenot refugee Denis Papin makes a ‘steam digester’ – an early form of pressure cooker – for softening bones, and demonstrates it to the Royal Society in England. A weighted valve allows pressure to build up to a predetermined level and is the forerunner of the later safety valve. The sytem is also used for the autoclave. |
| 1683 | Netherlands | Dutch microscopist Anton van Leeuwenhoek is the first to observe bacteria. |
| 1735 | Sweden | In his Systema Naturae/System of Nature, Swedish botanist Carolus Linnaeus (Carl von Linné) introduces a system for classifying plants based on their reproductive anatomy. In later editions be makes use of binomial nomenclature as a way to simply and stabilize the naming of species. |
| 1766 | Swiss Confederation | Swiss biologist Albrecht von Haller shows that nerves stimulate muscles to contract, and that all nerves lead to the spinal column and brain. His work lays the foundation of modern neurology. |
| 1767 | Italy | Italian biologist Lazzaro Spallanzani disproves Georges Buffon's theories of the spontaneous generation of life by preserving organic material in vials sealed by fusing the glass. |
| 1791 | Italy | Italian physiologist Luigi Galvani announces his observations on the muscular contraction of dead frogs, which he argues are caused by electricity. |
| 1809 | France | French biologist Jean-Baptiste de Lamarck publishes Philosophie zoologique/Zoological Philosophy in which he theorizes that organs improve with use and degenerate with disuse and that these environmentally adapted traits are inheritable. He also proposes a progressive theory of evolution. |
| 1826 | France | French physiologist René Joachim Henri Dutrochet carries out the first quantitative experiments on osmosis – the passage of a solvent through a semipermeable membrane. |
| 1831 | Scotland | Scottish botanist Robert Brown discovers the nucleus in plant cells. |
| 1836 | Germany | German physiologist Theodor Schwann discovers pepsin, the first known animal enzyme to be isolated. |
| 1838 | Germany | German botanist Matthias Jakob Schleiden publishes the article ‘Contributions to Phytogenesis’, in which he recognizes that cells are the fundamental units of all plant life. He is thus the first to formulate cell theory. |
| 1839 | Germany | German physiologist Theodor Schwann publishes Microscopic Investigations on the Accordance in the Structure and Growth of Plants and Animals, in which he argues that all animals and plants are composed of cells. Along with Matthias Schleiden, he thus founds modern cell theory. |
| 1856 | France | French chemist and microbiologist Louis Pasteur establishes that micro-organisms are responsible for fermentation, thus establishing the discipline of microbiology. |
| 1858 | Germany | The German biologist Rudolf Virchow publishes Die Cellularpathologie in ihrer Begründung auf physiologische und pathologische Gewebenlehre/Cellular Pathology as Based upon Physiological and Pathological Histology. In it he expands his ideas on the cell as the basis of life and disease, establishing cellular pathology as essential in understanding disease. |
| 24 November 1859 | England | Charles Darwin publishes On the Origin of Species by Natural Selection, which expounds his theory of evolution by natural selection, and by implication denies the truth of biblical creation and God's hand in Nature. It sells out immediately and revolutionizes biology. |
| 1866 | Austria | Austrian monk and botanist Gregor Mendel publishes ‘Versuche uber Pflanzenhybriden/Experiments on Plant Hybridization’ in the little known Proceedings of the Brunn Natural History Society in which he describes the inheritance of different characteristics in pea plants and proposes general methods for predicting patterns of inheritance, from one generation to the next. The work establishes the fundamental laws of heredity and is the basis of modern genetics. Mendel sends the paper to eminent biologists but is ignored. |
| 1866 | Germany | The German embryologist Ernst Haeckel proposes a third category of living beings intermediate between plants and animals. Called Protista, it consists mostly of microscopic organisms such as protozoans, algae, and fungi. |
| 1875 | Germany | The German cytologist Eduard Adolf Strasburger publishes Über Zellbildung und Zellteilung/On Cell Formation and Cell Division, in which he describes the process of mitosis. |
| 1877 | France | The French bacteriologist Louis Pasteur discovers that certain bacteria die when cultured with another type of bacteria, suggesting that the latter gives off a toxic substance – an antibiotic. |
| 5 May 1881 | France | French microbiologist Louis Pasteur vaccinates sheep against anthrax. It is the first infectious disease to be treated effectively with an antibacterial vaccine, and his success lays the foundations of immunology. |
| 24 March 1882 | Germany | German physician Robert Koch announces the discovery of Mycobacterium tuberculosis, the bacillus responsible for tuberculosis. This is the first time a micro-organism has been definitively associated with a human disease. |
| 1892 | Russia | Russian microbiologist Dimitry Iosifovich Ivanovsky publishes ‘On Two Diseases of Tobacco’ in which he announces that mosaic disease in tobacco is caused by micro-organisms too small to be seen through a microscope. |
| 1899 | Germany | German chemist Emil Hermann Fischer shows that proteins are polymers, or large molecules, comprised of amino acids. |
| 1900 | Netherlands, Gemany, Austria | Dutch geneticist Hugo Marie de Vries, German botanist Carl Erich Correns, and Austrian botanist Erich Tschermak von Seysenegg, simultaneously and independently, rediscover the Austrian monk Gregor Mendel's 1865 work on heredity. |
| 1901 | Austria | Austrian immunologist Karl Landsteiner discovers the ABO blood group system. |
| 1908 | | English mathematician Godfrey Hardy and German physician Wilhelm Weinberg establish the mathematical basis for population genetics. |
| 1910 | USA | US geneticist Thomas Hunt Morgan discovers that certain inherited characteristics of the fruit fly Drosophila melanogaster are sex linked. He later argues that because all sex-related characteristics are inherited together they are linearly arranged on the X-chromosome. |
| 1925 | USA | US geneticists Thomas Hunt Morgan, Alfred Sturtevant, and Calvin Blackman Bridges publish the results of their genetic experiments with the fruit fly Drosophila melanogaster, showing that genes can be mapped onto chromosomes. |
| 1930 | UK | English geneticist and statistician Ronald Fisher publishes The Genetical Theory of Natural Selection in which he synthesizes Mendelian genetics and Darwinian evolution. |
| 1948 | USA | US biologist Alfred Mirsky discovers ribonucleic acid (RNA) in chromosomes. |
| 1952 | USA | US biologists Alfred Day Hershey and Martha Chase use radioactive tracers to show that bacteriophages infect bacteria with DNA and not protein. |
| 1952 | UK | English biophysicist Rosalind Franklin uses X-ray diffraction to study the structure of DNA. She suggests that its sugar-phosphate backbone is on the outside – an important clue that leads to the elucidation of the structure of DNA the following year. |
| 25 April 1953 | England, USA | English molecular biologist Francis Crick and US biologist James Watson announce the discovery of the double helix structure of DNA, the basic material of heredity. They also theorize that if the strands are separated then each can form the template for the synthesis of an identical DNA molecule. It is perhaps the most important discovery in biology. |
| 1955 | USA | Spanish-born US molecular biologist Severo Ochoa discovers polynucleotide phosphorylase, the enzyme responsible for the synthesis of RNA (ribonucleic acid), which allows him to synthesize RNA. |
| 1955 | USA | The US geneticists Joshua Lederberg and Norton Zinder discover that some viruses carry part of the chromosome of one bacterium to another; called transduction it becomes an important tool in genetics research. |
| 1956 | USA | US biologists Maklon Hoagland and Paul Zamecnik discover transfer RNA (ribonucleic acid), which transfers amino acids, the building blocks of proteins, to the correct site on the messenger RNA. |
| 1956 | USA | US biochemist and physician Arthur Kornberg discovers how DNA (deoxyribonucleic acid) molecules replicate, allowing him to synthesize DNA in a test tube. |
| 1961 | England | English molecular biologist Francis Crick and South African chemist Sydney Brenner discover that each base triplet on the DNA strand codes for a specific amino acid in a protein molecule. |
| 1969 | USA | US geneticist Jonathan Beckwith and associates at the Harvard Medical School isolate a single gene for the first time. |
| 1970 | USA | US geneticist Hamilton Smith discovers the Hind II restriction enzyme that breaks the DNA strand at predictable places, making it an invaluable tool in recombinant DNA technology. |
| September 1970 | USA | Indian-born US biochemist Har Gobind Khorana assembles an artificial yeast gene from its chemical components. |
| 1975 | world | The gel-transfer hybridization technique for the detection of specific DNA (deoxyribonucleic acid) sequences is developed; it is a key development in genetic engineering. |
| 1977 | England | English biochemist Frederick Sanger describes the full sequence of 5,386 bases in the DNA (deoxyribonucleic acid) of virus phiX174 in Cambridge, England; the first sequencing of an entire genome. |
| 1981 | USA | US geneticists J W Gordon and F H Ruddle of the University of Ohio inject genes from one animal into the fertilized egg of a mouse that develop into mice with the foreign gene in many of the cells; the gene is then passed on to their offspring creating permanently altered (transgenic) animals; it is the first transfer of a gene from one animal species to another. |
| 27 February 1997 | UK | Scottish researcher Ian Wilmut of the Roslin Institute in Edinburgh, Scotland, announces that British geneticists have cloned an adult sheep. A cell was taken from the udder of the mother sheep and its DNA (deoxyribonucleic acid) combined with an unfertilized egg that had had its DNA removed. The fused cells were grown in the laboratory and then implanted into the uterus of a surrogate mother sheep. The resulting lamb, Dolly, came from an animal that was six years old. This is the first time cloning has been achieved using cells other than reproductive cells. The news is met with international calls to prevent the cloning of humans. |
| 7 January 1998 | World, Germany | Doctors meeting at the World Medical Association's conference in Hamburg, Germany, call for a worldwide ban on human cloning. US president Clinton calls for legislation banning cloning. |
| October 1998 | USA | US biologist French Anderson announces a technique that could cure inherited diseases by inserting a healthy gene to replace a damaged one. He calls for a full debate on the issue of gene therapy, which brings with it the dilemma of whether it is ethical to enable the choice of physical attributes such as eye colour and height. |
| 10 December 1998 | World | The first genetic blueprint for a whole multicellular animal – a nematode worm – is completed. The 97 million-letter code, which is published on the Internet, is for a tiny worm called Caenorhabditis elegans. The study began 15 years previously and cost £30 million. |
| October 1999 | Russia | A Russian expedition led by scientist Bernard Buigues discovers the carcass of a 23,000-year-old woolly mammoth frozen in Siberia. The carcass is flown to Khatanga, Russia, where scientists plan to clone the mammoth using an elephant as a surrogate mother. |
| 26 June 2000 | USA, UK | Scientists working on the Human Genome Project in London, England, and Washington, DC, announce that they have completed the first draft of the entire structure of human DNA. |
