History of Earth

For more detail of the geological history of Earth, see Geological history of Earth.
For more detail of the biological history of Earth, see History of life on Earth.
Earth's history with time-spans of the eons to scale. Ma means "million years ago".

The natural history of Earth concerns the development of planet Earth from its formation to the present day.[1][2] Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geological change and biological evolution.

The geological time scale (GTS), as defined by international convention,[3] depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history. Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula.[4][5][6] Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. While the Earth was in its earliest stage (Early Earth), a giant impact collision with a planet-sized body named Theia is thought to have formed the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water on the surface.

The Hadean eon represents the time before a reliable (fossil) record of life; it began with the formation of the planet and ended 4.0 billion years ago. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution. The succeeding eon is the Phanerozoic, divided into three eras: the Palaeozoic, an era of arthropods, fishes, and the first life on land; the Mesozoic, which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs; and the Cenozoic, which saw the rise of mammals. Recognizable humans emerged at most 2 million years ago, a vanishingly small period on the geological scale.

The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago,[7][8][9] during the Eoarchean Era, after a geological crust started to solidify following the earlier molten Hadean eon. There are microbial mat fossils such as stromatolites found in 3.48 billion-year-old sandstone discovered in Western Australia.[10][11][12] Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old metasedimentary rocks discovered in southwestern Greenland[13] as well as "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia.[14][15] According to one of the researchers, "If life arose relatively quickly on Earth … then it could be common in the universe."[14]

Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and began enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose, developed over time, and culminated in the Cambrian Explosion about 538.8 million years ago. This sudden diversification of life forms produced most of the major phyla known today, and divided the Proterozoic Eon from the Cambrian Period of the Paleozoic Era. It is estimated that 99 percent of all species that ever lived on Earth, over five billion,[16] have gone extinct.[17][18] Estimates on the number of Earth's current species range from 10 million to 14 million,[19] of which about 1.2 million are documented, but over 86 percent have not been described.[20]

The Earth's crust has constantly changed since its formation, as has life since its first appearance. Species continue to evolve, taking on new forms, splitting into daughter species, or going extinct in the face of ever-changing physical environments. The process of plate tectonics continues to shape the Earth's continents and oceans and the life they harbor.

  1. ^ Cite error: The named reference Stanley2005 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference TimeScale was invoked but never defined (see the help page).
  3. ^ "International Stratigraphic Chart". International Commission on Stratigraphy
  4. ^ Cite error: The named reference USGS1997 was invoked but never defined (see the help page).
  5. ^ Dalrymple, G. Brent (2001). "The age of the Earth in the twentieth century: a problem (mostly) solved". Special Publications, Geological Society of London. 190 (1): 205–221. Bibcode:2001GSLSP.190..205D. doi:10.1144/GSL.SP.2001.190.01.14. S2CID 130092094.
  6. ^ Manhesa, Gérard; Allègre, Claude J.; Dupréa, Bernard & Hamelin, Bruno (1980). "Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics". Earth and Planetary Science Letters. 47 (3): 370–382. Bibcode:1980E&PSL..47..370M. doi:10.1016/0012-821X(80)90024-2.
  7. ^ Schopf, J. William; Kudryavtsev, Anatoliy B.; Czaja, Andrew D.; Tripathi, Abhishek B. (5 October 2007). "Evidence of Archean life: Stromatolites and microfossils". Precambrian Research. 158 (3–4). Amsterdam: Elsevier: 141–155. Bibcode:2007PreR..158..141S. doi:10.1016/j.precamres.2007.04.009. ISSN 0301-9268.
  8. ^ Schopf, J. William (29 June 2006). "Fossil evidence of Archaean life". Philosophical Transactions of the Royal Society B. 361 (1470). London: Royal Society: 869–885. doi:10.1098/rstb.2006.1834. ISSN 0962-8436. PMC 1578735. PMID 16754604.
  9. ^ Raven, Peter H.; Johnson, George B. (2002). Biology (6th ed.). Boston, MA: McGraw Hill. p. 68. ISBN 978-0-07-112261-0. LCCN 2001030052. OCLC 45806501.
  10. ^ Borenstein, Seth (13 November 2013). "Oldest fossil found: Meet your microbial mom". Excite. Yonkers, NY: Mindspark Interactive Network. Associated Press. Retrieved 2015-06-02.
  11. ^ Pearlman, Jonathan (13 November 2013). "Oldest signs of life on Earth found". The Daily Telegraph. London. Archived from the original on 2022-01-11. Retrieved 2014-12-15.
  12. ^ Noffke, Nora; Christian, Daniel; Wacey, David; Hazen, Robert M. (16 November 2013). "Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia". Astrobiology. 13 (12). New Rochelle, NY: Mary Ann Liebert, Inc.: 1103–1124. Bibcode:2013AsBio..13.1103N. doi:10.1089/ast.2013.1030. ISSN 1531-1074. PMC 3870916. PMID 24205812.
  13. ^ Ohtomo, Yoko; Kakegawa, Takeshi; Ishida, Akizumi; et al. (January 2014). "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7 (1). London: Nature Publishing Group: 25–28. Bibcode:2014NatGe...7...25O. doi:10.1038/ngeo2025. ISSN 1752-0894.
  14. ^ a b Borenstein, Seth (19 October 2015). "Hints of life on what was thought to be desolate early Earth". Excite. Yonkers, NY: Mindspark Interactive Network. Associated Press. Archived from the original on 23 October 2015. Retrieved 8 October 2018.
  15. ^ Bell, Elizabeth A.; Boehnike, Patrick; Harrison, T. Mark; et al. (19 October 2015). "Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon" (PDF). Proc. Natl. Acad. Sci. U.S.A. 112 (47). Washington, DC: National Academy of Sciences: 14518–14521. Bibcode:2015PNAS..11214518B. doi:10.1073/pnas.1517557112. ISSN 1091-6490. PMC 4664351. PMID 26483481. Retrieved 2015-10-20. Early edition, published online before print.
  16. ^ Kunin, W.E.; Gaston, Kevin, eds. (1996). The Biology of Rarity: Causes and consequences of rare–common differences. Springer. ISBN 978-0-412-63380-5. Retrieved 26 May 2015.
  17. ^ 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.
  18. ^ Novacek, Michael J. (8 November 2014). "Prehistory's Brilliant Future". New York Times. Retrieved 2014-12-25.
  19. ^ Miller, G.; Spoolman, Scott (2012). Environmental Science – Biodiversity Is a Crucial Part of the Earth's Natural Capital. Cengage Learning. p. 62. ISBN 978-1-133-70787-5. Retrieved 2014-12-27.
  20. ^ Mora, C.; Tittensor, D.P.; Adl, S.; Simpson, A.G.; Worm, B. (23 August 2011). "How many species are there on Earth and in the ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. PMC 3160336. PMID 21886479.