Timeline of the evolutionary history of life

This timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, from kingdoms to species, and individual organisms and molecules, such as DNA and proteins. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species, living and extinct, have diverged through the process of evolution. More than 99 percent of all species, amounting to over five billion species,[1] that ever lived on Earth are estimated to be extinct.[2][3] Estimates on the number of Earth's current species range from 10 million to 14 million,[4] of which about 1.2 million have been documented and over 86 percent have not yet been described.[5] However, a May 2016 scientific report estimates that 1 trillion species are currently on Earth, with only one-thousandth of one percent described.[6]

While the dates given in this article are estimates based on scientific evidence, there has been controversy between more traditional views of increased biodiversity through a cone of diversity with the passing of time and the view that the basic pattern on Earth has been one of annihilation and diversification and that in certain past times, such as the Cambrian explosion, there was great diversity.[7][8]

  1. ^ McKinney 1997, p. 110
  2. ^ Stearns, Beverly Peterson; Stearns, S. C.; Stearns, Stephen C. (2000). Watching, from the Edge of Extinction. Yale University Press. p. preface x. ISBN 978-0-300-08469-6. Retrieved 30 May 2017.
  3. ^ Novacek, Michael J. (November 8, 2014). "Prehistory's Brilliant Future". The New York Times. New York. ISSN 0362-4331. Retrieved 2014-12-25.
  4. ^ Miller & Spoolman 2012, p. 62
  5. ^ Mora, Camilo; Tittensor, Derek P.; Adl, Sina; et al. (August 23, 2011). "How Many Species Are There on Earth and in the Ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. ISSN 1545-7885. PMC 3160336. PMID 21886479.
  6. ^ Staff (2 May 2016). "Researchers find that Earth may be home to 1 trillion species". National Science Foundation. Retrieved 11 April 2018.
  7. ^ Hickman, Crystal; Starn, Autumn. "The Burgess Shale & Models of Evolution". Reconstructions of the Burgess Shale and What They Mean... Morgantown, WV: West Virginia University. Retrieved 2015-10-18.
  8. ^ Barton et al. 2007, Figure 10.20 Four diagrams of evolutionary models