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The earliest known life forms on Earth are putative fossilized microorganisms found in hydrothermal vent precipitates.^[1] The earliest time that life forms first appeared on Earth is at least 3.77 billion years ago, possibly as early as 4.28 billion years,^[1] or even 4.5 billion years;^[3]^[4] not long after the oceans formed 4.41 billion years ago, and after the formation of the Earth 4.54 billion years ago.^[1]^[2]^[5]^[6] The earliest direct evidence of life on Earth are microfossils of microorganisms permineralized in 3.465-billion-year-old Australian Apex chert rocks.^[7]^[8]

Biosphere

Currently, Earth remains the only place in the universe known to harbor life.^[9]^[10] The Earth's biosphere extends down to at least 19 km (12 mi) below the surface,^[11]^[12]^[13]^[14] and up to at least 76 km (47 mi)^[15] into the atmosphere,^[16]^[17]^[18] and includes soil, hydrothermal vents, and rock.^[19]^[20] Further, the biosphere has been found to extend 800 m (2,600 ft; 0.50 mi) below the ice of Antarctica,^[21]^[22] and includes the deepest parts of the ocean,^[23]^[24]^[25] down to rocks kilometers below the sea floor.^[24]^[26]^[27] In July 2020, marine biologists reported that aerobic microorganisms (mainly), in "quasi-suspended animation", were found in organically-poor sediments, up to 101.5 million years old, 250 feet below the seafloor in the South Pacific Gyre (SPG) ("the deadest spot in the ocean"), and could be the longest-living life forms ever found.^[28]^[29] Under certain test conditions, life forms have been observed to survive in the vacuum of outer space.^[30]^[31] More recently, in August 2020, bacteria were found to survive for three years in outer space, according to studies conducted on the International Space Station.^[32]^[33] The total mass of the biosphere has been estimated to be as much as 4 trillion tons of carbon.^[34] According to one researcher, "You can find microbes everywhere – [they are] extremely adaptable to conditions, and survive wherever they are."^[24]

Of all species of life forms that ever lived on Earth, over five billion,^[35] more than 99%, are estimated to be extinct.^[36]^[37] Some estimates on the number of Earth's current species range from 10 million to 14 million,^[38] of which about 1.2 million have been documented and over 86 percent remain undescribed.^[39] However, a May 2016 scientific report estimates 1 trillion species currently on Earth, with only one-thousandth of one percent described.^[40] Additionally, there are an estimated 10 nonillion (10 to the 31st power) individual viruses (including the related virions) on Earth, the most numerous type of biological entity,^[41] and which some biologists consider to be life forms.^[42] Moreover, there are more individual viruses than all the estimated stars in the universe;^[43] which, in turn, are considered to be more numerous than all the grains of beach sand on planet Earth.^[44] About 200 virus types are known to cause diseases in humans.^[43] Other possible virus-like forms, some pathogenic, less likely to be considered living, much smaller than viruses and possibly much more primitive, include viroids, virusoids and prions.^[45]

NASA scientists study earliest known life forms on Earth

Stromatolites studied in the Pilbara region of North West Australia

Earliest life forms

Archaea, prokaryotic microbes, were first found in extreme environments, such as hydrothermal vents.

The age of the Earth is about 4.54 billion years;^[46]^[47]^[48] the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago.^[49]^[50]^[51] There is evidence that suggests life began as early as 4.5 billion years ago.^[3]^[4]

A December 2017 report stated that 3.465-billion-year-old Australian Apex chert rocks once contained microorganisms, the earliest direct evidence of life on Earth.^[7]^[8] A 2013 publication announced the discovery of microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.^[52]^[53]^[54]^[55] Evidence of biogenic graphite,^[56] and possibly stromatolites,^[57]^[58]^[59] were discovered in 3.7 billion-year-old metasedimentary rocks in southwestern Greenland, and described in 2014 in the journal Nature. Potential "remains of life" were found in 4.1 billion-year-old rocks in Western Australia, and described in a 2015 study.^[60]

A 2016 genetic study concluded that the last universal common ancestor (LUCA) may have lived in deep-sea hydrothermal vents 3.5 to 3.8 billion years ago.^[63] A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean.^[3]^[4] In March 2017, fossilized microorganisms (microfossils) were announced to have been discovered in hydrothermal vent precipitates from an ancient sea-bed in the Nuvvuagittuq Belt of Quebec, Canada. These may be as old as 4.28 billion years, the oldest evidence of life on Earth, suggesting "an almost instantaneous emergence of life" after ocean formation 4.41 billion years ago.^[1]^[2]^[5]^[6] Some researchers even speculate that life may have started nearly 4.5 billion years ago.^[3]^[4] According to biologist Stephen Blair Hedges, "If life arose relatively quickly on Earth … then it could be common in the universe."^[64]^[65]^[66]

As for life on land, in 2019 scientists reported the discovery of a fossilized fungus, named Ourasphaira giraldae, in the Canadian Arctic, that may have grown on land a billion years ago, well before plants were living on land.^[67]^[68]^[69] In July 2018, scientists reported that the earliest life on land may have been bacteria 3.22 billion years ago.^[70] In May 2017, evidence of microbial life on land may have been found in 3.48 billion-year-old geyserite in the Pilbara Craton of Western Australia.^[71]^[72]

In January 2018, a study found that 4.5 billion-year-old meteorites found on Earth contained liquid water along with prebiotic complex organic substances that may be ingredients for life.^[62]^[73]

Gallery

Earliest known life forms (click "show" on right for more images)

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Quaternary ice age*

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*Ice Ages

Stromatolites may have been made by microbes moving upward to avoid being smothered by sediment.^[58]^[59]
Stromatolites left behind by cyanobacteria are one of the oldest fossils of life on Earth.
The cyanobacterial-algal mat, salty lake on the White Sea seaside.

Wrinkled Kinneyia-type sedimentary structures formed beneath cohesive microbial mats in peritidal zones.^[74]
Kinneyia-like structure in the Grimsby Formation (Silurian) exposed in Niagara Gorge, NY.

Template:LifeOnEarth

References

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External links

Biota (Taxonomicon)
Life (Systema Naturae 2000)
Vitae (BioLib)
Wikispecies – a free directory of life
Google Images: Earliest known life forms
Video (24:32): "Migration of Life in the Universe" on YouTube – Gary Ruvkun, 2019.

[NAT-20170301-1] Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; slack, John F.; Rittner, Martin; Pirajno, Franco; O'Neil, Jonathan; Little, Crispin T. S. (2 March 2017). "Evidence for early life in Earth's oldest hydrothermal vent precipitates" (PDF). Nature. 543 (7643): 60–64. Bibcode:2017Natur.543...60D. doi:10.1038/nature21377. PMID 28252057. S2CID 2420384.

[NYT-20170301-2] Zimmer, Carl (1 March 2017). "Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest". New York Times. Retrieved 2 March 2017.

[PHY-20180820-3] Staff (20 August 2018). "A timescale for the origin and evolution of all of life on Earth". Phys.org. Retrieved 20 August 2018.

[NAT-20180820-4] Betts, Holly C.; Putick, Mark N.; Clark, James W.; Williams, Tom A.; Donoghue, Philip C.J.; Pisani, Davide (20 August 2018). "Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin". Nature. 2 (10): 1556–1562. doi:10.1038/s41559-018-0644-x. PMC 6152910. PMID 30127539.

[BBC-20170301-5] Ghosh, Pallab (1 March 2017). "Earliest evidence of life on Earth 'found". BBC News. Retrieved 2 March 2017.

[4.3b_oldest-6] Dunham, Will (1 March 2017). "Canadian bacteria-like fossils called oldest evidence of life". Reuters. Retrieved 1 March 2017.

[WU-20171218-7] Tyrell, Kelly April (18 December 2017). "Oldest fossils ever found show life on Earth began before 3.5 billion years ago". University of Wisconsin–Madison. Retrieved 18 December 2017.

[PNAS-2017-8] Schopf, J. William; Kitajima, Kouki; Spicuzza, Michael J.; Kudryavtsev, Anatolly B.; Valley, John W. (2017). "SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions". PNAS. 115 (1): 53–58. Bibcode:2018PNAS..115...53S. doi:10.1073/pnas.1718063115. PMC 5776830. PMID 29255053.

[NASA-1990-9] Graham, Robert W. (February 1990). "Extraterrestrial Life in the Universe" (PDF). NASA (NASA Technical Memorandum 102363). Lewis Research Center, Cleveland, Ohio. Retrieved 2 June 2015.

[Alterman-2009-10] Altermann, Wladyslaw (2009). "From Fossils to Astrobiology – A Roadmap to Fata Morgana?". In Seckbach, Joseph; Walsh, Maud (eds.). From Fossils to Astrobiology: Records of Life on Earth and the Search for Extraterrestrial Biosignatures. Cellular Origin, Life in Extreme Habitats and Astrobiology. Vol. 12. Dordrecht, the Netherlands; London: Springer Science+Business Media. p. xvii. ISBN 978-1-4020-8836-0. LCCN 2008933212.

[EA-20181211-11] Deep Carbon Observatory (10 December 2018). "Life in deep Earth totals 15 to 23 billion tons of carbon – hundreds of times more than humans – Deep Carbon Observatory collaborators, exploring the 'Galapagos of the deep,' add to what's known, unknown, and unknowable about Earth's most pristine ecosystem". EurekAlert!. Retrieved 11 December 2018.

[SA-20181211-12] Dockrill, Peter (11 December 2018). "Scientists Reveal a Massive Biosphere of Life Hidden Under Earth's Surface". Science Alert. Retrieved 11 December 2018.

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 == Biosphere ==
-Currently, Earth remains the only place in the [[universe]] known to harbor [[life]].<ref name="NASA-1990">{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900013148.pdf |title=Extraterrestrial Life in the Universe |last=Graham |first=Robert W. |date=February 1990 |place=[[Glenn Research Center|Lewis Research Center]], Cleveland, Ohio |website=[[NASA]] |type=NASA Technical Memorandum 102363 |accessdate=2 June 2015}}</ref><ref name="Alterman-2009">{{cite book |last=Altermann |first=Wladyslaw |year=2009 |chapter=From Fossils to Astrobiology – A Roadmap to Fata Morgana? |editor1-last=Seckbach |editor1-first=Joseph |editor2-last=Walsh |editor2-first=Maud |title=From Fossils to Astrobiology: Records of Life on Earth and the Search for Extraterrestrial Biosignatures |series=Cellular Origin, Life in Extreme Habitats and Astrobiology |volume=12 |location=Dordrecht, the Netherlands; London |publisher=[[Springer Science+Business Media]] |isbn=978-1-4020-8836-0 |lccn=2008933212|p=xvii}}</ref> The Earth's [[biosphere]] extends down to at least {{convert|12|mi|km|order=flip|abbr=on}} below the surface,<ref name="EA-20181211">{{cite news|url=https://www.eurekalert.org/pub_releases/2018-12/tca-lid120318.php|title=Life in deep Earth totals 15 to 23 billion tons of carbon – hundreds of times more than humans – Deep Carbon Observatory collaborators, exploring the 'Galapagos of the deep,' add to what's known, unknown, and unknowable about Earth's most pristine ecosystem|author=Deep Carbon Observatory|date=10 December 2018|work=[[EurekAlert!]]|accessdate=11 December 2018|author-link=Deep Carbon Observatory}}</ref><ref name="SA-20181211">{{cite news|url=https://www.sciencealert.com/scientists-lift-lid-on-massive-biosphere-of-life-hidden-under-earth-s-surface|title=Scientists Reveal a Massive Biosphere of Life Hidden Under Earth's Surface|last=Dockrill|first=Peter|date=11 December 2018|work=Science Alert|accessdate=11 December 2018}}</ref><ref name="TI-20181211">{{cite news|url=https://www.independent.co.uk/news/science/deep-life-microbes-underground-bacteria-earth-surface-carbon-observatory-science-study-a8677521.html|title=Massive 'deep life' study reveals billions of tonnes of microbes living far beneath Earth's surface|last=Gabbatiss|first=Josh|date=11 December 2018|work=[[The Independent]]|accessdate=11 December 2018}}</ref><ref name="NYT-20181219">{{cite news|url=https://www.nytimes.com/2018/12/19/science/subsurface-microbes.html|title=Deep Beneath Your Feet, They Live in the Octillions – The real journey to the center of the Earth has begun, and scientists are discovering subsurface microbial beings that shake up what we think we know about life.|last=Klein|first=JoAnna|date=19 December 2018|work=[[The New York Times]]|accessdate=21 December 2018}}</ref> and up to at least {{convert|47|mi|km|order=flip|abbr=on}}<ref name="SA-20191104">{{cite news |last=Loeb |first=Abraham |authorlink=Abraham Loeb |title=Did Life from Earth Escape the Solar System Eons Ago? – There's no proof that it happene&nbsp;– but it's not impossible |url=https://blogs.scientificamerican.com/observations/did-life-from-earth-escape-the-solar-system-eons-ago/ |date=4 November 2019 |work=[[Scientific American]] |accessdate=5 November 2019 }}</ref> into the [[Atmosphere of Earth|atmosphere]],<ref name="SD-19980625-UG">{{cite web|url=https://www.sciencedaily.com/releases/1998/08/980825080732.htm|title=First-Ever Scientific Estimate Of Total Bacteria On Earth Shows Far Greater Numbers Than Ever Known Before|author=University of Georgia|date=25 August 1998|work=[[Science Daily]]|accessdate=10 November 2014}}</ref><ref name="ABM-20150112">{{cite web|url=http://www.astrobio.net/extreme-life/life-might-thrive-dozen-miles-beneath-earths-surface/|title=Life Might Thrive a Dozen Miles Beneath Earth's Surface|last=Hadhazy|first=Adam|date=12 January 2015|work=[[Astrobiology Magazine]]|accessdate=11 March 2017}}</ref><ref name="BBC-20151124">{{cite web|url=http://www.bbc.com/earth/story/20151124-meet-the-strange-creatures-that-live-in-solid-rock-deep-underground|title=The Strange Beasts That Live In Solid Rock Deep Underground|last=Fox-Skelly|first=Jasmin|date=24 November 2015|work=[[BBC online]]|accessdate=11 March 2017}}</ref> and includes [[pedosphere|soil]], [[Hydrothermal vent#Biological communities|hydrothermal vents]], and [[endolith|rock]].<ref name="NC-20200402">{{cite journal |author=Suzuki, Yohey |display-authors=et al. |title=Deep microbial proliferation at the basalt interface in 33.5–104 million-year-old oceanic crust |date=2 April 2020 |journal=[[Communications Biology]] |volume=3 |issue=136 |page=136 |doi=10.1038/s42003-020-0860-1 |pmid=32242062 |pmc=7118141 |doi-access=free }}</ref><ref name="EA-20200402">{{cite news |author=[[University of Tokyo]] |title=Discovery of life in solid rock deep beneath sea may inspire new search for life on Mars – Bacteria live in tiny clay-filled cracks in solid rock millions of years old |url=https://www.eurekalert.org/pub_releases/2020-04/uot-dol033020.php |date=2 April 2020 |work=[[EurekAlert!]] |accessdate=2 April 2020 }}</ref> Further, the biosphere has been found to extend {{convert|800|m|ft mi|abbr=on}} below the ice of [[Antarctica]],<ref name="NAT-20140820">{{cite journal|last=Fox|first=Douglas|date=20 August 2014|title=Lakes under the ice: Antarctica's secret garden|journal=[[Nature (journal)|Nature]]|volume=512|issue=7514|pages=244–246|bibcode=2014Natur.512..244F|doi=10.1038/512244a|pmid=25143097|doi-access=free}}</ref><ref name="FRB-20140820">{{cite web|url=https://www.forbes.com/sites/ericmack/2014/08/20/life-confirmed-under-antarctic-ice-is-space-next/|title=Life Confirmed Under Antarctic Ice; Is Space Next?|last=Mack|first=Eric|date=20 August 2014|work=[[Forbes]]|accessdate=21 August 2014}}</ref> and includes the [[Deep sea#Biology|deepest parts of the ocean]],<ref name="mariana_britannica">{{cite encyclopedia|title=Mariana Trench|encyclopedia=[[Encyclopædia Britannica]]|publisher=[[Encyclopædia Britannica]]|url=http://www.britannica.com/place/Pacific-Ocean|id=}}</ref><ref name="LS-20130317">{{cite web|url=http://www.livescience.com/27954-microbes-mariana-trench.html|title=Microbes Thrive in Deepest Spot on Earth|last=Choi|first=Charles Q.|date=17 March 2013|website=[[LiveScience]]|accessdate=17 March 2013}}</ref><ref name="NG-20130317">{{cite journal |last1=Glud|first1=Ronnie|last2=Wenzhöfer|first2=Frank|last3=Middelboe|first3=Mathias|last4=Oguri|first4=Kazumasa|last5=Turnewitsch|first5=Robert|last6=Canfield|first6=Donald E.|last7=Kitazato|first7=Hiroshi|date=17 March 2013|title=High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth|journal=[[Nature Geoscience]]|volume=6|issue=4|pages=284–288|bibcode=2013NatGe...6..284G|doi=10.1038/ngeo1773}}</ref> down to rocks kilometers below the sea floor.<ref name="LS-20130317" /><ref name="LS-20130314">{{cite web|url=http://www.livescience.com/27899-ocean-subsurface-ecosystem-found.html|title=Intraterrestrials: Life Thrives in Ocean Floor|last=Oskin|first=Becky|date=14 March 2013|website=[[LiveScience]]|accessdate=17 March 2013}}</ref><ref name="BBC-20141215-RM">{{cite news|url=https://www.bbc.com/news/science-environment-30489814|title=Microbes discovered by deepest marine drill analysed|last=Morelle|first=Rebecca|date=15 December 2014|work=[[BBC News]]|accessdate=15 December 2014}}</ref> In July 2020, [[Marine biology|marine biologists]] reported that [[Aerobic organism|aerobic]] [[microorganism]]s (mainly), in "[[Suspended animation|quasi-suspended animation]]", were found in [[Sediment|organically-poor sediments]], up to 101.5 million years old, 250 feet below the [[Seabed|seafloor]] in the [[South Pacific Gyre]] (SPG) ("the deadest spot in the ocean"), and could be the [[List of longest-living organisms|longest-living life forms]] ever found.<ref name="NYT-2200728">{{cite news |last=Wu |first=Katherine J. |title=These Microbes May Have Survived 100 Million Years Beneath the Seafloor - Rescued from their cold, cramped and nutrient-poor homes, the bacteria awoke in the lab and grew. |url=https://www.nytimes.com/2020/07/28/science/microbes-100-million-years-old.html |date=28 July 2020 |accessdate=31 July 2020 }}</ref><ref name="NC-20200728">{{cite journal |author=Morono, Yuki |display-authors=et al. |title=Aerobic microbial life persists in oxic marine sediment as old as 101.5 million years |url=https://www.nature.com/articles/s41467-020-17330-1 |date=28 July 2020 |journal=[[Nature Communications]] |volume=11 |number=3626 |accessdate=31 July 2020 }}</ref> Under certain test conditions, life forms have been observed to [[Panspermia#Research in outer space|survive in the vacuum of outer space]].<ref name="Dose">{{cite journal|last1=Dose|first1=K.|last2=Bieger-Dose|first2=A.|last3=Dillmann|first3=R.|last4=Gill|first4=M.|last5=Kerz|first5=O.|last6=Klein|first6=A.|last7=Meinert|first7=H.|last8=Nawroth|first8=T.|last9=Risi|first9=S.|year=1995|title=ERA-experiment "space biochemistry"|journal=Advances in Space Research|volume=16|issue=8|pages=119–129|bibcode=1995AdSpR..16..119D|doi=10.1016/0273-1177(95)00280-R|pmid=11542696|last10=Stridde|first10=C.}}</ref><ref name="Horneck">{{cite journal|author1=Horneck G.|author2=Eschweiler, U.|author3=Reitz, G.|author4=Wehner, J.|author5=Willimek, R.|author6=Strauch, K.|year=1995|title=Biological responses to space: results of the experiment "Exobiological Unit" of ERA on EURECA I|journal=Adv. Space Res.|volume=16|issue=8|pages=105–118|bibcode=1995AdSpR..16..105H|doi=10.1016/0273-1177(95)00279-N|pmid=11542695}}</ref> More recently, in August 2020, [[bacteria]] were found to survive for three years in [[outer space]], according to studies conducted on the [[International Space Station]].<ref name="CNN-20200826">{{cite news |last=Strickland |first=Ashley |title=Bacteria from Earth can survive in space and could endure the trip to Mars, according to new study |url=https://www.cnn.com/2020/08/26/world/earth-mars-bacteria-space-scn/index.html |date=26 August 2020 |work=[[CNN News]] |accessdate=26 August 2020 }}</ref><ref name="FM-20200826">{{cite journal |author=Kawaguchi, Yuko |display-authors=et al. |title=DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space |url=https://www.frontiersin.org/articles/10.3389/fmicb.2020.02050/full |date=26 August 2020 |journal=[[Frontiers in Microbiology]] |doi=10.3389/fmicb.2020.02050 |accessdate=26 August 2020 }}</ref> The total mass of the [[biosphere]] has been estimated to be as much as 4 trillion tons of [[carbon]].<ref name="AGCI-2015">{{cite web|url=http://www.agci.org/classroom/biosphere/index.php|title=The Biosphere: Diversity of Life|author=<!--Staff writer(s); no by-line.-->|work=Aspen Global Change Institute|location=Basalt, CO|accessdate=19 July 2015}}</ref> According to one researcher, "You can find [[microbe]]s everywhere – [they are] extremely adaptable to conditions, and survive wherever they are."<ref name="LS-20130317" />
+Currently, Earth remains the only place in the [[universe]] known to harbor [[life]].<ref name="NASA-1990">{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900013148.pdf |title=Extraterrestrial Life in the Universe |last=Graham |first=Robert W. |date=February 1990 |place=[[Glenn Research Center|Lewis Research Center]], Cleveland, Ohio |website=[[NASA]] |type=NASA Technical Memorandum 102363 |accessdate=2 June 2015}}</ref><ref name="Alterman-2009">{{cite book |last=Altermann |first=Wladyslaw |year=2009 |chapter=From Fossils to Astrobiology – A Roadmap to Fata Morgana? |editor1-last=Seckbach |editor1-first=Joseph |editor2-last=Walsh |editor2-first=Maud |title=From Fossils to Astrobiology: Records of Life on Earth and the Search for Extraterrestrial Biosignatures |series=Cellular Origin, Life in Extreme Habitats and Astrobiology |volume=12 |location=Dordrecht, the Netherlands; London |publisher=[[Springer Science+Business Media]] |isbn=978-1-4020-8836-0 |lccn=2008933212|p=xvii}}</ref> The Earth's [[biosphere]] extends down to at least {{convert|12|mi|km|order=flip|abbr=on}} below the surface,<ref name="EA-20181211">{{cite news|url=https://www.eurekalert.org/pub_releases/2018-12/tca-lid120318.php|title=Life in deep Earth totals 15 to 23 billion tons of carbon – hundreds of times more than humans – Deep Carbon Observatory collaborators, exploring the 'Galapagos of the deep,' add to what's known, unknown, and unknowable about Earth's most pristine ecosystem|author=Deep Carbon Observatory|date=10 December 2018|work=[[EurekAlert!]]|accessdate=11 December 2018|author-link=Deep Carbon Observatory}}</ref><ref name="SA-20181211">{{cite news|url=https://www.sciencealert.com/scientists-lift-lid-on-massive-biosphere-of-life-hidden-under-earth-s-surface|title=Scientists Reveal a Massive Biosphere of Life Hidden Under Earth's Surface|last=Dockrill|first=Peter|date=11 December 2018|work=Science Alert|accessdate=11 December 2018}}</ref><ref name="TI-20181211">{{cite news|url=https://www.independent.co.uk/news/science/deep-life-microbes-underground-bacteria-earth-surface-carbon-observatory-science-study-a8677521.html|title=Massive 'deep life' study reveals billions of tonnes of microbes living far beneath Earth's surface|last=Gabbatiss|first=Josh|date=11 December 2018|work=[[The Independent]]|accessdate=11 December 2018}}</ref><ref name="NYT-20181219">{{cite news|url=https://www.nytimes.com/2018/12/19/science/subsurface-microbes.html|title=Deep Beneath Your Feet, They Live in the Octillions – The real journey to the center of the Earth has begun, and scientists are discovering subsurface microbial beings that shake up what we think we know about life.|last=Klein|first=JoAnna|date=19 December 2018|work=[[The New York Times]]|accessdate=21 December 2018}}</ref> and up to at least {{convert|47|mi|km|order=flip|abbr=on}}<ref name="SA-20191104">{{cite news |last=Loeb |first=Abraham |authorlink=Abraham Loeb |title=Did Life from Earth Escape the Solar System Eons Ago? – There's no proof that it happene&nbsp;– but it's not impossible |url=https://blogs.scientificamerican.com/observations/did-life-from-earth-escape-the-solar-system-eons-ago/ |date=4 November 2019 |work=[[Scientific American]] |accessdate=5 November 2019 }}</ref> into the [[Atmosphere of Earth|atmosphere]],<ref name="SD-19980625-UG">{{cite web|url=https://www.sciencedaily.com/releases/1998/08/980825080732.htm|title=First-Ever Scientific Estimate Of Total Bacteria On Earth Shows Far Greater Numbers Than Ever Known Before|author=University of Georgia|date=25 August 1998|work=[[Science Daily]]|accessdate=10 November 2014}}</ref><ref name="ABM-20150112">{{cite web|url=http://www.astrobio.net/extreme-life/life-might-thrive-dozen-miles-beneath-earths-surface/|title=Life Might Thrive a Dozen Miles Beneath Earth's Surface|last=Hadhazy|first=Adam|date=12 January 2015|work=[[Astrobiology Magazine]]|accessdate=11 March 2017}}</ref><ref name="BBC-20151124">{{cite web|url=http://www.bbc.com/earth/story/20151124-meet-the-strange-creatures-that-live-in-solid-rock-deep-underground|title=The Strange Beasts That Live In Solid Rock Deep Underground|last=Fox-Skelly|first=Jasmin|date=24 November 2015|work=[[BBC online]]|accessdate=11 March 2017}}</ref> and includes [[pedosphere|soil]], [[Hydrothermal vent#Biological communities|hydrothermal vents]], and [[endolith|rock]].<ref name="NC-20200402">{{cite journal |author=Suzuki, Yohey |display-authors=et al. |title=Deep microbial proliferation at the basalt interface in 33.5–104 million-year-old oceanic crust |date=2 April 2020 |journal=[[Communications Biology]] |volume=3 |issue=136 |page=136 |doi=10.1038/s42003-020-0860-1 |pmid=32242062 |pmc=7118141 |doi-access=free }}</ref><ref name="EA-20200402">{{cite news |author=[[University of Tokyo]] |title=Discovery of life in solid rock deep beneath sea may inspire new search for life on Mars – Bacteria live in tiny clay-filled cracks in solid rock millions of years old |url=https://www.eurekalert.org/pub_releases/2020-04/uot-dol033020.php |date=2 April 2020 |work=[[EurekAlert!]] |accessdate=2 April 2020 }}</ref> Further, the biosphere has been found to extend {{convert|800|m|ft mi|abbr=on}} below the ice of [[Antarctica]],<ref name="NAT-20140820">{{cite journal|last=Fox|first=Douglas|date=20 August 2014|title=Lakes under the ice: Antarctica's secret garden|journal=[[Nature (journal)|Nature]]|volume=512|issue=7514|pages=244–246|bibcode=2014Natur.512..244F|doi=10.1038/512244a|pmid=25143097|doi-access=free}}</ref><ref name="FRB-20140820">{{cite web|url=https://www.forbes.com/sites/ericmack/2014/08/20/life-confirmed-under-antarctic-ice-is-space-next/|title=Life Confirmed Under Antarctic Ice; Is Space Next?|last=Mack|first=Eric|date=20 August 2014|work=[[Forbes]]|accessdate=21 August 2014}}</ref> and includes the [[Deep sea#Biology|deepest parts of the ocean]],<ref name="mariana_britannica">{{cite encyclopedia|title=Mariana Trench|encyclopedia=[[Encyclopædia Britannica]]|publisher=[[Encyclopædia Britannica]]|url=http://www.britannica.com/place/Pacific-Ocean|id=}}</ref><ref name="LS-20130317">{{cite web|url=http://www.livescience.com/27954-microbes-mariana-trench.html|title=Microbes Thrive in Deepest Spot on Earth|last=Choi|first=Charles Q.|date=17 March 2013|website=[[LiveScience]]|accessdate=17 March 2013}}</ref><ref name="NG-20130317">{{cite journal |last1=Glud|first1=Ronnie|last2=Wenzhöfer|first2=Frank|last3=Middelboe|first3=Mathias|last4=Oguri|first4=Kazumasa|last5=Turnewitsch|first5=Robert|last6=Canfield|first6=Donald E.|last7=Kitazato|first7=Hiroshi|date=17 March 2013|title=High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth|journal=[[Nature Geoscience]]|volume=6|issue=4|pages=284–288|bibcode=2013NatGe...6..284G|doi=10.1038/ngeo1773}}</ref> down to rocks kilometers below the sea floor.<ref name="LS-20130317" /><ref name="LS-20130314">{{cite web|url=http://www.livescience.com/27899-ocean-subsurface-ecosystem-found.html|title=Intraterrestrials: Life Thrives in Ocean Floor|last=Oskin|first=Becky|date=14 March 2013|website=[[LiveScience]]|accessdate=17 March 2013}}</ref><ref name="BBC-20141215-RM">{{cite news|url=https://www.bbc.com/news/science-environment-30489814|title=Microbes discovered by deepest marine drill analysed|last=Morelle|first=Rebecca|date=15 December 2014|work=[[BBC News]]|accessdate=15 December 2014}}</ref> In July 2020, [[Marine biology|marine biologists]] reported that [[Aerobic organism|aerobic]] [[microorganism]]s (mainly), in "[[Suspended animation|quasi-suspended animation]]", were found in [[Sediment|organically-poor sediments]], up to 101.5 million years old, 250 feet below the [[Seabed|seafloor]] in the [[South Pacific Gyre]] (SPG) ("the deadest spot in the ocean"), and could be the [[List of longest-living organisms|longest-living life forms]] ever found.<ref name="NYT-2200728">{{cite news |last=Wu |first=Katherine J. |title=These Microbes May Have Survived 100 Million Years Beneath the Seafloor - Rescued from their cold, cramped and nutrient-poor homes, the bacteria awoke in the lab and grew. |url=https://www.nytimes.com/2020/07/28/science/microbes-100-million-years-old.html |date=28 July 2020 |accessdate=31 July 2020 }}</ref><ref name="NC-20200728">{{cite journal |author=Morono, Yuki |display-authors=et al. |title=Aerobic microbial life persists in oxic marine sediment as old as 101.5 million years |date=28 July 2020 |journal=[[Nature Communications]] |volume=11 |number=3626 |page=3626 |doi=10.1038/s41467-020-17330-1 |pmid=32724059 |pmc=7387439 }}</ref> Under certain test conditions, life forms have been observed to [[Panspermia#Research in outer space|survive in the vacuum of outer space]].<ref name="Dose">{{cite journal|last1=Dose|first1=K.|last2=Bieger-Dose|first2=A.|last3=Dillmann|first3=R.|last4=Gill|first4=M.|last5=Kerz|first5=O.|last6=Klein|first6=A.|last7=Meinert|first7=H.|last8=Nawroth|first8=T.|last9=Risi|first9=S.|year=1995|title=ERA-experiment "space biochemistry"|journal=Advances in Space Research|volume=16|issue=8|pages=119–129|bibcode=1995AdSpR..16..119D|doi=10.1016/0273-1177(95)00280-R|pmid=11542696|last10=Stridde|first10=C.}}</ref><ref name="Horneck">{{cite journal|author1=Horneck G.|author2=Eschweiler, U.|author3=Reitz, G.|author4=Wehner, J.|author5=Willimek, R.|author6=Strauch, K.|year=1995|title=Biological responses to space: results of the experiment "Exobiological Unit" of ERA on EURECA I|journal=Adv. Space Res.|volume=16|issue=8|pages=105–118|bibcode=1995AdSpR..16..105H|doi=10.1016/0273-1177(95)00279-N|pmid=11542695}}</ref> More recently, in August 2020, [[bacteria]] were found to survive for three years in [[outer space]], according to studies conducted on the [[International Space Station]].<ref name="CNN-20200826">{{cite news |last=Strickland |first=Ashley |title=Bacteria from Earth can survive in space and could endure the trip to Mars, according to new study |url=https://www.cnn.com/2020/08/26/world/earth-mars-bacteria-space-scn/index.html |date=26 August 2020 |work=[[CNN News]] |accessdate=26 August 2020 }}</ref><ref name="FM-20200826">{{cite journal |author=Kawaguchi, Yuko |display-authors=et al. |title=DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space |date=26 August 2020 |journal=[[Frontiers in Microbiology]] |volume=11 |doi=10.3389/fmicb.2020.02050 |s2cid=221300151 }}</ref> The total mass of the [[biosphere]] has been estimated to be as much as 4 trillion tons of [[carbon]].<ref name="AGCI-2015">{{cite web|url=http://www.agci.org/classroom/biosphere/index.php|title=The Biosphere: Diversity of Life|author=<!--Staff writer(s); no by-line.-->|work=Aspen Global Change Institute|location=Basalt, CO|accessdate=19 July 2015}}</ref> According to one researcher, "You can find [[microbe]]s everywhere – [they are] extremely adaptable to conditions, and survive wherever they are."<ref name="LS-20130317" />
-Of all [[species]] of life forms that ever lived on Earth, over five billion,<ref name="Book-Biology">{{cite book|url=https://books.google.com/books?id=4LHnCAAAQBAJ&pg=PA110&lpg=PA110&dq#v=onepage|title=The Biology of Rarity: Causes and consequences of rare – common differences|year=1996|isbn=978-0412633805|editor1=Kunin, W.E.|accessdate=26 May 2015|editor2=Gaston, Kevin}}</ref> more than 99%, are estimated to be [[Extinction|extinct]].<ref name="StearnsStearns2000">{{cite book |last1=Stearns |first1=Beverly Peterson |last2=Stearns |first2=S. C. |last3=Stearns |first3=Stephen C. |title=Watching, from the Edge of Extinction |url=https://books.google.com/books?id=0BHeC-tXIB4C&q=99%20percent#v=onepage |year=2000 |publisher=[[Yale University Press]] |isbn=978-0-300-08469-6|page=preface x |accessdate=30 May 2017 }}</ref><ref name="NYT-20141108-MJN">{{cite news |last=Novacek |first=Michael J. |title=Prehistory's Brilliant Future |url=https://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |date=8 November 2014 |work=[[New York Times]] |accessdate=25 December 2014 }}</ref> Some estimates on the number of Earth's current species range from 10 million to 14 million,<ref name="MillerSpoolman2012">{{cite book|author1=G. Miller|author2=Scott Spoolman |title=Environmental Science – Biodiversity Is a Crucial Part of the Earth's Natural Capital |url=https://books.google.com/books?id=NYEJAAAAQBAJ&pg=PA62 |date=2012 |publisher=[[Cengage Learning]] |isbn=978-1-133-70787-5 |page=62 |accessdate=27 December 2014 }}</ref> of which about 1.2 million have been documented and over 86 percent remain undescribed.<ref name="PLoS-20110823">{{cite journal |last1=Mora |first1=C. |last2=Tittensor |first2=D.P. |last3=Adl |first3=S. |last4=Simpson |first4=A.G. |last5=Worm |first5=B. |title=How many species are there on Earth and in the ocean? |date=23 August 2011 |journal=[[PLOS Biology]] |doi=10.1371/journal.pbio.1001127 |pmid=21886479 |pmc=3160336 |volume=9 |issue=8 |pages=e1001127}}</ref> However, a May 2016 scientific report estimates 1 trillion species currently on Earth, with only one-thousandth of one percent described.<ref name="NSF-2016002">{{cite news |author=Staff |title=Researchers find that Earth may be home to 1 trillion species |url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=138446 |date=2 May 2016 |work=[[National Science Foundation]] |accessdate=6 May 2016 }}</ref> Additionally, there are an estimated 10 nonillion (10 to the 31st power) individual [[virus]]es (including the related [[virion]]s) on Earth, the most numerous type of biological entity,<ref name="NRM-2005">{{cite journal | vauthors = Edwards RA, Rohwer F |title=Viral metagenomics |journal=[[Nature Reviews Microbiology]] |volume=3 |issue=6 |pages=504–10 |date=June 2005 |pmid=15886693 |doi=10.1038/nrmicro1163 }}</ref> and which some [[Virus|biologists consider to be life forms]].<ref name="SA-20080808">{{cite web |last=Villarreal |first=Luis P. |title=Are Viruses Alive? - Although viruses challenge our concept of what "living" means, they are vital members of the web of life |url=https://www.scientificamerican.com/article/are-viruses-alive-2004/ |date=8 August 2008 |work=[[Scientific American]] |accessdate=19 May 2020 }}</ref> Moreover, there are more individual viruses than all the estimated stars in the universe;<ref name="NG-20200415">{{cite news |last=Wu |first=Katherine J. |title=There are more viruses than stars in the universe. Why do only some infect us? - More than a quadrillion quadrillion individual viruses exist on Earth, but most are not poised to hop into humans. Can we find the ones that are? |url=https://www.nationalgeographic.com/science/2020/04/factors-allow-viruses-infect-humans-coronavirus/ |date=15 April 2020 |work=[[National Geographic Society]] |accessdate=18 May 2020 }}</ref> which, in turn, are considered to be more numerous than all the grains of beach sand on planet Earth.<ref name="SWIN-20020201">{{cite web |last=Mackie |first=Glen |title=To see the Universe in a Grain of Taranaki Sand  |url=https://astronomy.swin.edu.au/~gmackie/billions.html |date=1 February 2002 |work=[[Swinburne University of Technology]] |accessdate=18 May 2020 }}</ref> About 200 virus types are known to cause [[Social history of viruses|diseases in humans]].<ref name="NG-20200415" /> Other possible virus-like forms, some [[pathogen]]ic, less likely to be considered living, much smaller than viruses and possibly much more primitive, include [[viroid]]s, [[virusoid]]s and [[prion]]s.<ref name="MB-20190813">{{cite web |author=Staff |title=Difference among virus, virion, viroid, virusoid and prion |url=https://medium.com/@nehamicrobio83/difference-among-virus-virion-viroid-virusoid-and-prion-a01f22f06825 |date=13 August 2019 |work=Microbiology Easy Notes |accessdate=18 May 2020 }}</ref>
+Of all [[species]] of life forms that ever lived on Earth, over five billion,<ref name="Book-Biology">{{cite book|url=https://books.google.com/books?id=4LHnCAAAQBAJ&pg=PA110&lpg=PA110&dq#v=onepage|title=The Biology of Rarity: Causes and consequences of rare – common differences|year=1996|isbn=978-0412633805|editor1=Kunin, W.E.|accessdate=26 May 2015|editor2=Gaston, Kevin}}</ref> more than 99%, are estimated to be [[Extinction|extinct]].<ref name="StearnsStearns2000">{{cite book |last1=Stearns |first1=Beverly Peterson |last2=Stearns |first2=S. C. |last3=Stearns |first3=Stephen C. |title=Watching, from the Edge of Extinction |url=https://books.google.com/books?id=0BHeC-tXIB4C&q=99%20percent#v=onepage |year=2000 |publisher=[[Yale University Press]] |isbn=978-0-300-08469-6|page=preface x |accessdate=30 May 2017 }}</ref><ref name="NYT-20141108-MJN">{{cite news |last=Novacek |first=Michael J. |title=Prehistory's Brilliant Future |url=https://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |date=8 November 2014 |work=[[New York Times]] |accessdate=25 December 2014 }}</ref> Some estimates on the number of Earth's current species range from 10 million to 14 million,<ref name="MillerSpoolman2012">{{cite book|author1=G. Miller|author2=Scott Spoolman |title=Environmental Science – Biodiversity Is a Crucial Part of the Earth's Natural Capital |url=https://books.google.com/books?id=NYEJAAAAQBAJ&pg=PA62 |date=2012 |publisher=[[Cengage Learning]] |isbn=978-1-133-70787-5 |page=62 |accessdate=27 December 2014 }}</ref> of which about 1.2 million have been documented and over 86 percent remain undescribed.<ref name="PLoS-20110823">{{cite journal |last1=Mora |first1=C. |last2=Tittensor |first2=D.P. |last3=Adl |first3=S. |last4=Simpson |first4=A.G. |last5=Worm |first5=B. |title=How many species are there on Earth and in the ocean? |date=23 August 2011 |journal=[[PLOS Biology]] |doi=10.1371/journal.pbio.1001127 |pmid=21886479 |pmc=3160336 |volume=9 |issue=8 |pages=e1001127}}</ref> However, a May 2016 scientific report estimates 1 trillion species currently on Earth, with only one-thousandth of one percent described.<ref name="NSF-2016002">{{cite news |author=Staff |title=Researchers find that Earth may be home to 1 trillion species |url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=138446 |date=2 May 2016 |work=[[National Science Foundation]] |accessdate=6 May 2016 }}</ref> Additionally, there are an estimated 10 nonillion (10 to the 31st power) individual [[virus]]es (including the related [[virion]]s) on Earth, the most numerous type of biological entity,<ref name="NRM-2005">{{cite journal | vauthors = Edwards RA, Rohwer F |title=Viral metagenomics |journal=[[Nature Reviews Microbiology]] |volume=3 |issue=6 |pages=504–10 |date=June 2005 |pmid=15886693 |doi=10.1038/nrmicro1163 |s2cid=8059643 }}</ref> and which some [[Virus|biologists consider to be life forms]].<ref name="SA-20080808">{{cite web |last=Villarreal |first=Luis P. |title=Are Viruses Alive? - Although viruses challenge our concept of what "living" means, they are vital members of the web of life |url=https://www.scientificamerican.com/article/are-viruses-alive-2004/ |date=8 August 2008 |work=[[Scientific American]] |accessdate=19 May 2020 }}</ref> Moreover, there are more individual viruses than all the estimated stars in the universe;<ref name="NG-20200415">{{cite news |last=Wu |first=Katherine J. |title=There are more viruses than stars in the universe. Why do only some infect us? - More than a quadrillion quadrillion individual viruses exist on Earth, but most are not poised to hop into humans. Can we find the ones that are? |url=https://www.nationalgeographic.com/science/2020/04/factors-allow-viruses-infect-humans-coronavirus/ |date=15 April 2020 |work=[[National Geographic Society]] |accessdate=18 May 2020 }}</ref> which, in turn, are considered to be more numerous than all the grains of beach sand on planet Earth.<ref name="SWIN-20020201">{{cite web |last=Mackie |first=Glen |title=To see the Universe in a Grain of Taranaki Sand  |url=https://astronomy.swin.edu.au/~gmackie/billions.html |date=1 February 2002 |work=[[Swinburne University of Technology]] |accessdate=18 May 2020 }}</ref> About 200 virus types are known to cause [[Social history of viruses|diseases in humans]].<ref name="NG-20200415" /> Other possible virus-like forms, some [[pathogen]]ic, less likely to be considered living, much smaller than viruses and possibly much more primitive, include [[viroid]]s, [[virusoid]]s and [[prion]]s.<ref name="MB-20190813">{{cite web |author=Staff |title=Difference among virus, virion, viroid, virusoid and prion |url=https://medium.com/@nehamicrobio83/difference-among-virus-virion-viroid-virusoid-and-prion-a01f22f06825 |date=13 August 2019 |work=Microbiology Easy Notes |accessdate=18 May 2020 }}</ref>
 {{multipleimage |align=center|direction=horizontal |header=NASA scientists study earliest known life forms on Earth |width= |image1=PIA23551-MarsRover-OldEarthFossilsStudied-20190819.jpg |caption1=<div align="center">[[:File:PIA23551-MarsRover-OldEarthFossilsStudied-20190819.jpg|Stromatolites studied in the Pilbara region of North West Australia]]</div> |width1=200 |image2=NASA-MarsScienceTeams-StudyAncientLifeInAustralia.webm |caption2=<div align="center">[[:File:NASA-MarsScienceTeams-StudyAncientLifeInAustralia.webm|Related video: 3:03]]</div> |width2=268 |footer= }}
 == Earliest life forms ==
 [[File:Halobacteria.jpg|thumb|upright=0.80|left|[[Archaea]], [[Prokaryotes|prokaryotic]] [[microorganism|microbes]], were first found in [[extreme environment]]s, such as [[hydrothermal vent]]s.]]
-The [[age of the Earth]] is about 4.54 billion years;<ref name="USGS1997">{{cite web |url=http://pubs.usgs.gov/gip/geotime/age.html |title=Age of the Earth |date=9 July 2007 |website=[[United States Geological Survey]] |accessdate=2006-01-10}}</ref><ref>{{cite journal |last=Dalrymple |first=G. Brent |authorlink=Brent Dalrymple  |title=The age of the Earth in the twentieth century: a problem (mostly) solved |journal=Special Publications, Geological Society of London |date=2001 |volume=190 |issue=1 |pages=205–221 |doi=10.1144/GSL.SP.2001.190.01.14 |bibcode = 2001GSLSP.190..205D }}</ref><ref>{{cite journal |last1=Manhesa |first1=Gérard |last2=Allègre |first2=Claude J. |authorlink2=Claude Allègre |last3=Dupréa |first3=Bernard |last4=Hamelin |first4=Bruno |date=May 1980 |title=Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics |journal=[[Earth and Planetary Science Letters]] |volume=47 |issue=3 |pages=370–382 |bibcode=1980E&PSL..47..370M |doi=10.1016/0012-821X(80)90024-2 |issn=0012-821X}}</ref> the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago.<ref name="Origin1">{{cite journal |last1=Schopf |first1=J. William |authorlink1=J. William Schopf |last2=Kudryavtsev |first2=Anatoliy B. |last3=Czaja |first3=Andrew D. |last4=Tripathi |first4=Abhishek B. |date=5 October 2007 |title=Evidence of Archean life: Stromatolites and microfossils |journal=[[Precambrian Research]] |volume=158 |pages=141–155 |issue=3–4 |doi=10.1016/j.precamres.2007.04.009 |issn=0301-9268|bibcode=2007PreR..158..141S }}</ref><ref name="Origin2">{{cite journal |last=Schopf |first=J. William |date=29 June 2006 |title=Fossil evidence of Archaean life |journal=[[Philosophical Transactions of the Royal Society B]] |volume=361 |issue=1470 |pages=869–885 |doi=10.1098/rstb.2006.1834 |issn=0962-8436 |pmid=16754604 |pmc=1578735}}</ref><ref name="RavenJohnson2002">{{cite book |last1=Raven |first1=Peter H. |authorlink1=Peter H. Raven |last2=Johnson |first2=George B. |authorlink2=George B. Johnson |year=2002 |title=Biology |url=https://archive.org/details/biologyrave00rave |url-access=registration |edition=6th |location=Boston, MA |publisher=[[McGraw-Hill Education|McGraw-Hill]] |isbn=978-0-07-112261-0 |lccn=2001030052 |oclc=45806501 |p=[https://archive.org/details/biologyrave00rave/page/68 68]}}</ref> There is evidence that suggests life began as early as 4.5 billion years ago.<ref name="PHY-20180820" /><ref name="NAT-20180820" />
+The [[age of the Earth]] is about 4.54 billion years;<ref name="USGS1997">{{cite web |url=http://pubs.usgs.gov/gip/geotime/age.html |title=Age of the Earth |date=9 July 2007 |website=[[United States Geological Survey]] |accessdate=2006-01-10}}</ref><ref>{{cite journal |last=Dalrymple |first=G. Brent |authorlink=Brent Dalrymple  |title=The age of the Earth in the twentieth century: a problem (mostly) solved |journal=Special Publications, Geological Society of London |date=2001 |volume=190 |issue=1 |pages=205–221 |doi=10.1144/GSL.SP.2001.190.01.14 |bibcode = 2001GSLSP.190..205D |s2cid=130092094 }}</ref><ref>{{cite journal |last1=Manhesa |first1=Gérard |last2=Allègre |first2=Claude J. |authorlink2=Claude Allègre |last3=Dupréa |first3=Bernard |last4=Hamelin |first4=Bruno |date=May 1980 |title=Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics |journal=[[Earth and Planetary Science Letters]] |volume=47 |issue=3 |pages=370–382 |bibcode=1980E&PSL..47..370M |doi=10.1016/0012-821X(80)90024-2 |issn=0012-821X}}</ref> the earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago.<ref name="Origin1">{{cite journal |last1=Schopf |first1=J. William |authorlink1=J. William Schopf |last2=Kudryavtsev |first2=Anatoliy B. |last3=Czaja |first3=Andrew D. |last4=Tripathi |first4=Abhishek B. |date=5 October 2007 |title=Evidence of Archean life: Stromatolites and microfossils |journal=[[Precambrian Research]] |volume=158 |pages=141–155 |issue=3–4 |doi=10.1016/j.precamres.2007.04.009 |issn=0301-9268|bibcode=2007PreR..158..141S }}</ref><ref name="Origin2">{{cite journal |last=Schopf |first=J. William |date=29 June 2006 |title=Fossil evidence of Archaean life |journal=[[Philosophical Transactions of the Royal Society B]] |volume=361 |issue=1470 |pages=869–885 |doi=10.1098/rstb.2006.1834 |issn=0962-8436 |pmid=16754604 |pmc=1578735}}</ref><ref name="RavenJohnson2002">{{cite book |last1=Raven |first1=Peter H. |authorlink1=Peter H. Raven |last2=Johnson |first2=George B. |authorlink2=George B. Johnson |year=2002 |title=Biology |url=https://archive.org/details/biologyrave00rave |url-access=registration |edition=6th |location=Boston, MA |publisher=[[McGraw-Hill Education|McGraw-Hill]] |isbn=978-0-07-112261-0 |lccn=2001030052 |oclc=45806501 |p=[https://archive.org/details/biologyrave00rave/page/68 68]}}</ref> There is evidence that suggests life began as early as 4.5 billion years ago.<ref name="PHY-20180820" /><ref name="NAT-20180820" />
-A December 2017 report stated that 3.465-billion-year-old [[Australia]]n [[Apex chert]] rocks once contained [[microorganism]]s, the earliest ''direct'' evidence of life on Earth.<ref name="WU-20171218" /><ref name="PNAS-2017" /> A 2013 publication announced the discovery of [[microbial mat]] [[fossil]]s in 3.48 billion-year-old [[sandstone]] in Western Australia.<ref name="AP-20131113">{{cite news|url=http://apnews.excite.com/article/20131113/DAA1VSC01.html|title=Oldest fossil found: Meet your microbial mom|last=Borenstein|first=Seth|date=13 November 2013|work=[[Excite]]|accessdate=2 June 2015|publisher=[[Mindspark Interactive Network]]|agency=[[Associated Press]]|location=Yonkers, NY}}</ref><ref name="TG-20131113-JP">{{cite news|url=https://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html|title=Oldest signs of life on Earth found|last=Pearlman|first=Jonathan|date=13 November 2013|newspaper=[[The Daily Telegraph]]|accessdate=2014-12-15|publisher=[[Telegraph Media Group]]|location=London}}</ref><ref name="AST-20131108">{{cite journal|last1=Noffke|first1=Nora|last2=Christian|first2=Daniel|last3=Wacey|first3=David|last4=Hazen|first4=Robert M.|authorlink4=Robert Hazen|date=16 November 2013|title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia|journal=[[Astrobiology (journal)|Astrobiology]]|volume=13|issue=12|pages=1103–1124|bibcode=2013AsBio..13.1103N|doi=10.1089/ast.2013.1030|issn=1531-1074|pmc=3870916|pmid=24205812}}</ref><ref name="NC-20170509">{{cite journal|last1=Djokic|first1=Tara|last2=Van Kranendonk|first2=Martin J.|last3=Campbell|first3=Kathleen A.|last4=Walter|first4=Malcolm R.|last5=Ward|first5=Colin R.|date=9 May 2017|title=Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits|journal=[[Nature Communications]]|volume=8|pages=15263|bibcode=2017NatCo...815263D|doi=10.1038/ncomms15263|pmc=5436104|pmid=28486437}}</ref> Evidence of [[biogenic substance|biogenic]] [[graphite]],<ref name="NG-20131208">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |s2cid=54767854 |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 |issn=1752-0894}}</ref> and possibly [[stromatolite]]s,<ref name="NYT-20160831">{{cite news |last=Wade |first=Nicholas |title=World's Oldest Fossils Found in Greenland |url=https://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |date=31 August 2016 |work=[[New York Times]] |accessdate=31 August 2016 }}</ref><ref name="NAT-20160922">{{cite journal |last=Allwood |first=Abigail C. |title=Evidence of life in Earth's oldest rocks |date=22 September 2016 |journal=[[Nature (journal)|Nature]] |volume=537 |issue=7621 |pages=500–5021 |doi=10.1038/nature19429 |pmid=27580031 }}</ref><ref name="NG-20181017">{{cite web |last=Wei-Haas |first=Maya |title='World's oldest fossils' may just be pretty rocks – Analysis of 3.7-billion-year-old outcrops has reignited controversy over when life on Earth began. |url=https://www.nationalgeographic.com/science/2018/10/news-oldest-stromatolite-fossilized-life-rocks-greenland/ |date=17 October 2018 |work=[[National Geographic]] |accessdate=19 October 2018 }}</ref> were discovered in 3.7 billion-year-old [[Metasediment|metasedimentary rocks]] in southwestern [[Greenland]], and described in 2014 in the journal [[Nature (journal)|Nature]]. Potential "[[Biotic material|remains]] of life" were found in 4.1 billion-year-old rocks in Western Australia, and described in a 2015 study.<ref name="PNAS-20151019">{{cite journal|title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|last1=Bell|first1=Elizabeth|last2=Boehnke|first2=Patrick|date=24 November 2015|journal=[[Proceedings of the National Academy of Sciences of the United States of America]]|last3=Harrison|first3=T. Mark|last4=Mao|first4=Wendy L.|volume=112|issue=47|pages=14518–14521|doi=10.1073/pnas.1517557112|pmid=26483481|pmc=4664351|bibcode=2015PNAS..11214518B}}</ref>
+A December 2017 report stated that 3.465-billion-year-old [[Australia]]n [[Apex chert]] rocks once contained [[microorganism]]s, the earliest ''direct'' evidence of life on Earth.<ref name="WU-20171218" /><ref name="PNAS-2017" /> A 2013 publication announced the discovery of [[microbial mat]] [[fossil]]s in 3.48 billion-year-old [[sandstone]] in Western Australia.<ref name="AP-20131113">{{cite news|url=http://apnews.excite.com/article/20131113/DAA1VSC01.html|title=Oldest fossil found: Meet your microbial mom|last=Borenstein|first=Seth|date=13 November 2013|work=[[Excite]]|accessdate=2 June 2015|publisher=[[Mindspark Interactive Network]]|agency=[[Associated Press]]|location=Yonkers, NY}}</ref><ref name="TG-20131113-JP">{{cite news|url=https://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html|title=Oldest signs of life on Earth found|last=Pearlman|first=Jonathan|date=13 November 2013|newspaper=[[The Daily Telegraph]]|accessdate=2014-12-15|publisher=[[Telegraph Media Group]]|location=London}}</ref><ref name="AST-20131108">{{cite journal|last1=Noffke|first1=Nora|last2=Christian|first2=Daniel|last3=Wacey|first3=David|last4=Hazen|first4=Robert M.|authorlink4=Robert Hazen|date=16 November 2013|title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia|journal=[[Astrobiology (journal)|Astrobiology]]|volume=13|issue=12|pages=1103–1124|bibcode=2013AsBio..13.1103N|doi=10.1089/ast.2013.1030|issn=1531-1074|pmc=3870916|pmid=24205812}}</ref><ref name="NC-20170509">{{cite journal|last1=Djokic|first1=Tara|last2=Van Kranendonk|first2=Martin J.|last3=Campbell|first3=Kathleen A.|last4=Walter|first4=Malcolm R.|last5=Ward|first5=Colin R.|date=9 May 2017|title=Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits|journal=[[Nature Communications]]|volume=8|pages=15263|bibcode=2017NatCo...815263D|doi=10.1038/ncomms15263|pmc=5436104|pmid=28486437}}</ref> Evidence of [[biogenic substance|biogenic]] [[graphite]],<ref name="NG-20131208">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |s2cid=54767854 |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 |issn=1752-0894}}</ref> and possibly [[stromatolite]]s,<ref name="NYT-20160831">{{cite news |last=Wade |first=Nicholas |title=World's Oldest Fossils Found in Greenland |url=https://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |date=31 August 2016 |work=[[New York Times]] |accessdate=31 August 2016 }}</ref><ref name="NAT-20160922">{{cite journal |last=Allwood |first=Abigail C. |title=Evidence of life in Earth's oldest rocks |date=22 September 2016 |journal=[[Nature (journal)|Nature]] |volume=537 |issue=7621 |pages=500–5021 |doi=10.1038/nature19429 |pmid=27580031 |s2cid=205250633 }}</ref><ref name="NG-20181017">{{cite web |last=Wei-Haas |first=Maya |title='World's oldest fossils' may just be pretty rocks – Analysis of 3.7-billion-year-old outcrops has reignited controversy over when life on Earth began. |url=https://www.nationalgeographic.com/science/2018/10/news-oldest-stromatolite-fossilized-life-rocks-greenland/ |date=17 October 2018 |work=[[National Geographic]] |accessdate=19 October 2018 }}</ref> were discovered in 3.7 billion-year-old [[Metasediment|metasedimentary rocks]] in southwestern [[Greenland]], and described in 2014 in the journal [[Nature (journal)|Nature]]. Potential "[[Biotic material|remains]] of life" were found in 4.1 billion-year-old rocks in Western Australia, and described in a 2015 study.<ref name="PNAS-20151019">{{cite journal|title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|last1=Bell|first1=Elizabeth|last2=Boehnke|first2=Patrick|date=24 November 2015|journal=[[Proceedings of the National Academy of Sciences of the United States of America]]|last3=Harrison|first3=T. Mark|last4=Mao|first4=Wendy L.|volume=112|issue=47|pages=14518–14521|doi=10.1073/pnas.1517557112|pmid=26483481|pmc=4664351|bibcode=2015PNAS..11214518B}}</ref>
-[[File:Porous chondriteIDP.jpg|thumb|The theory of [[panspermia]] suggests that [[life]] on [[Earth]] may have come from biological matter carried by [[space dust]]<ref name="ARX-20171106">{{cite journal |last=Berera |first=Arjun |title=Space dust collisions as a planetary escape mechanism |journal=Astrobiology |volume=17 |issue=12 |pages=1274–1282 |date=6 November 2017 |arxiv=1711.01895 |accessdate=|bibcode=2017AsBio..17.1274B |doi=10.1089/ast.2017.1662 |pmid=29148823 }}</ref> or [[meteorite]]s.<ref name="SA-20180110" />]]
+[[File:Porous chondriteIDP.jpg|thumb|The theory of [[panspermia]] suggests that [[life]] on [[Earth]] may have come from biological matter carried by [[space dust]]<ref name="ARX-20171106">{{cite journal |last=Berera |first=Arjun |title=Space dust collisions as a planetary escape mechanism |journal=Astrobiology |volume=17 |issue=12 |pages=1274–1282 |date=6 November 2017 |arxiv=1711.01895 |accessdate=|bibcode=2017AsBio..17.1274B |doi=10.1089/ast.2017.1662 |pmid=29148823 |s2cid=126012488 }}</ref> or [[meteorite]]s.<ref name="SA-20180110" />]]
-A 2016 genetic study concluded that the [[last universal common ancestor]] (LUCA) may have lived in deep-sea [[hydrothermal vents]] 3.5 to 3.8 billion years ago.<ref>{{Cite journal|last1=Weiss|first1=Madeline C.|last2=Sousa|first2=Filipa L.|last3=Mrnjavac|first3=Natalia|last4=Neukirchen|first4=Sinje|last5=Roettger|first5=Mayo|last6=Nelson-Sathi|first6=Shijulal|last7=Martin|first7=William F.|date=September 2016|title=The physiology and habitat of the last universal common ancestor|journal=Nature Microbiology|volume=1|issue=9|pages=16116|doi=10.1038/nmicrobiol.2016.116|pmid=27562259|issn=2058-5276}}</ref> A 2018 study from the [[University of Bristol]], applying a [[molecular clock]] model, places the LUCA shortly after 4.5&nbsp;billion years ago, within the [[Hadean]].<ref name="PHY-20180820" /><ref name="NAT-20180820" /> In March 2017, fossilized [[microorganism]]s ([[Micropaleontology#Microfossils|microfossils]]) were announced to have been discovered in [[hydrothermal vent]] [[precipitates]] from an ancient sea-bed in the [[Nuvvuagittuq Greenstone Belt|Nuvvuagittuq Belt]] of Quebec, Canada. These may be as old as 4.28 billion years, the oldest evidence of life on Earth, suggesting "an almost instantaneous emergence of life" after [[Origin of water on Earth#Water in the development of Earth|ocean formation 4.41 billion years ago]].<ref name="NAT-20170301">{{cite journal |author=Dodd, Matthew S. |author2=Papineau, Dominic |author3=Grenne, Tor |author4=slack, John F. |author5=Rittner, Martin |author6=Pirajno, Franco |author7=O'Neil, Jonathan |author8=Little, Crispin T. S. |title=Evidence for early life in Earth's oldest hydrothermal vent precipitates|journal=Nature |volume=543 |issue=7643 |pages=60–64 |date=2 March 2017 | doi=10.1038/nature21377|pmid=28252057 |bibcode=2017Natur.543...60D |url=http://eprints.whiterose.ac.uk/112179/1/ppnature21377_Dodd_for%20Symplectic.pdf }}</ref><ref name="NYT-20170301">{{cite news |last=Zimmer |first=Carl |authorlink=Carl Zimmer |title=Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest |url=https://www.nytimes.com/2017/03/01/science/earths-oldest-bacteria-fossils.html |date=1 March 2017 |work=[[New York Times]] |accessdate=2 March 2017 }}</ref><ref name="BBC-20170301">{{cite web |last=Ghosh |first=Pallab |title=Earliest evidence of life on Earth 'found |url=https://www.bbc.co.uk/news/science-environment-39117523 |work=[[BBC News]] |date=1 March 2017 |accessdate=2 March 2017}}</ref><ref name="4.3b oldest">{{cite news |last1=Dunham |first1=Will |title=Canadian bacteria-like fossils called oldest evidence of life |url=http://ca.reuters.com/article/topNews/idCAKBN16858B?sp=true |date=1 March 2017 |newspaper=[[Reuters]] |accessdate=1 March 2017 }}</ref> Some researchers even speculate that life may have started nearly 4.5 billion years ago.<ref name="PHY-20180820">{{cite web |author=Staff |title=A timescale for the origin and evolution of all of life on Earth |url=https://phys.org/news/2018-08-timescale-evolution-life-earth.html |date=20 August 2018 |work=[[Phys.org]] |accessdate=20 August 2018 }}</ref><ref name="NAT-20180820">{{cite journal |last1=Betts |first1=Holly C. |last2=Putick |first2=Mark N. |last3=Clark |first3=James W. |last4=Williams |first4=Tom A. |last5=Donoghue |first5=Philip C.J. |last6=Pisani |first6=Davide |title=Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin |date=20 August 2018 |journal=[[Nature (journal)|Nature]] |volume=2 |issue=10 |pages=1556–1562 |doi=10.1038/s41559-018-0644-x |pmid=30127539 |pmc=6152910 }}</ref> According to biologist [[Stephen Blair Hedges]], "If life arose relatively quickly on Earth … then it could be common in the [[universe]]."<ref name="AP-20151019">{{cite news|url=https://apnews.com/e6be2537b4cd46ffb9c0585bae2b2e51|title=Hints of life on what was thought to be desolate early Earth|last=Borenstein|first=Seth|date=19 October 2015|accessdate=9 October 2018|newspaper=[[Associated Press]]}}</ref><ref name="CSM-20151020">{{cite news|url=https://www.csmonitor.com/Science/2015/1020/When-did-life-first-emerge-on-Earth-Maybe-a-lot-earlier-than-we-thought|title=When did life first emerge on Earth? Maybe a lot earlier than we thought|last=Schouten|first=Lucy|date=20 October 2015|work=[[The Christian Science Monitor]]|accessdate=9 October 2018|archive-url=https://web.archive.org/web/20160322214217/http://www.csmonitor.com/Science/2015/1020/When-did-life-first-emerge-on-Earth-Maybe-a-lot-earlier-than-we-thought|archive-date=22 March 2016|url-status= |publisher=[[Christian Science Publishing Society]]|location=Boston, Massachusetts|issn=0882-7729}}</ref><ref name="IND-20171002">{{cite web|url=https://www.independent.co.uk/news/science/origins-life-ponds-organisms-earth-age-study-a7978906.html|title=Life first emerged in 'warm little ponds' almost as old as the Earth itself – Charles Darwin's famous idea backed by new scientific study|last=Johnston|first=Ian|date=2 October 2017|work=[[The Independent]]|accessdate=2 October 2017}}</ref>
+A 2016 genetic study concluded that the [[last universal common ancestor]] (LUCA) may have lived in deep-sea [[hydrothermal vents]] 3.5 to 3.8 billion years ago.<ref>{{Cite journal|last1=Weiss|first1=Madeline C.|last2=Sousa|first2=Filipa L.|last3=Mrnjavac|first3=Natalia|last4=Neukirchen|first4=Sinje|last5=Roettger|first5=Mayo|last6=Nelson-Sathi|first6=Shijulal|last7=Martin|first7=William F.|date=September 2016|title=The physiology and habitat of the last universal common ancestor|journal=Nature Microbiology|volume=1|issue=9|pages=16116|doi=10.1038/nmicrobiol.2016.116|pmid=27562259|s2cid=2997255|issn=2058-5276}}</ref> A 2018 study from the [[University of Bristol]], applying a [[molecular clock]] model, places the LUCA shortly after 4.5&nbsp;billion years ago, within the [[Hadean]].<ref name="PHY-20180820" /><ref name="NAT-20180820" /> In March 2017, fossilized [[microorganism]]s ([[Micropaleontology#Microfossils|microfossils]]) were announced to have been discovered in [[hydrothermal vent]] [[precipitates]] from an ancient sea-bed in the [[Nuvvuagittuq Greenstone Belt|Nuvvuagittuq Belt]] of Quebec, Canada. These may be as old as 4.28 billion years, the oldest evidence of life on Earth, suggesting "an almost instantaneous emergence of life" after [[Origin of water on Earth#Water in the development of Earth|ocean formation 4.41 billion years ago]].<ref name="NAT-20170301">{{cite journal |author=Dodd, Matthew S. |author2=Papineau, Dominic |author3=Grenne, Tor |author4=slack, John F. |author5=Rittner, Martin |author6=Pirajno, Franco |author7=O'Neil, Jonathan |author8=Little, Crispin T. S. |title=Evidence for early life in Earth's oldest hydrothermal vent precipitates|journal=Nature |volume=543 |issue=7643 |pages=60–64 |date=2 March 2017 | doi=10.1038/nature21377|pmid=28252057 |bibcode=2017Natur.543...60D |s2cid=2420384 |url=http://eprints.whiterose.ac.uk/112179/1/ppnature21377_Dodd_for%20Symplectic.pdf }}</ref><ref name="NYT-20170301">{{cite news |last=Zimmer |first=Carl |authorlink=Carl Zimmer |title=Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest |url=https://www.nytimes.com/2017/03/01/science/earths-oldest-bacteria-fossils.html |date=1 March 2017 |work=[[New York Times]] |accessdate=2 March 2017 }}</ref><ref name="BBC-20170301">{{cite web |last=Ghosh |first=Pallab |title=Earliest evidence of life on Earth 'found |url=https://www.bbc.co.uk/news/science-environment-39117523 |work=[[BBC News]] |date=1 March 2017 |accessdate=2 March 2017}}</ref><ref name="4.3b oldest">{{cite news |last1=Dunham |first1=Will |title=Canadian bacteria-like fossils called oldest evidence of life |url=http://ca.reuters.com/article/topNews/idCAKBN16858B?sp=true |date=1 March 2017 |newspaper=[[Reuters]] |accessdate=1 March 2017 }}</ref> Some researchers even speculate that life may have started nearly 4.5 billion years ago.<ref name="PHY-20180820">{{cite web |author=Staff |title=A timescale for the origin and evolution of all of life on Earth |url=https://phys.org/news/2018-08-timescale-evolution-life-earth.html |date=20 August 2018 |work=[[Phys.org]] |accessdate=20 August 2018 }}</ref><ref name="NAT-20180820">{{cite journal |last1=Betts |first1=Holly C. |last2=Putick |first2=Mark N. |last3=Clark |first3=James W. |last4=Williams |first4=Tom A. |last5=Donoghue |first5=Philip C.J. |last6=Pisani |first6=Davide |title=Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin |date=20 August 2018 |journal=[[Nature (journal)|Nature]] |volume=2 |issue=10 |pages=1556–1562 |doi=10.1038/s41559-018-0644-x |pmid=30127539 |pmc=6152910 }}</ref> According to biologist [[Stephen Blair Hedges]], "If life arose relatively quickly on Earth … then it could be common in the [[universe]]."<ref name="AP-20151019">{{cite news|url=https://apnews.com/e6be2537b4cd46ffb9c0585bae2b2e51|title=Hints of life on what was thought to be desolate early Earth|last=Borenstein|first=Seth|date=19 October 2015|accessdate=9 October 2018|newspaper=[[Associated Press]]}}</ref><ref name="CSM-20151020">{{cite news|url=https://www.csmonitor.com/Science/2015/1020/When-did-life-first-emerge-on-Earth-Maybe-a-lot-earlier-than-we-thought|title=When did life first emerge on Earth? Maybe a lot earlier than we thought|last=Schouten|first=Lucy|date=20 October 2015|work=[[The Christian Science Monitor]]|accessdate=9 October 2018|archive-url=https://web.archive.org/web/20160322214217/http://www.csmonitor.com/Science/2015/1020/When-did-life-first-emerge-on-Earth-Maybe-a-lot-earlier-than-we-thought|archive-date=22 March 2016|url-status= |publisher=[[Christian Science Publishing Society]]|location=Boston, Massachusetts|issn=0882-7729}}</ref><ref name="IND-20171002">{{cite web|url=https://www.independent.co.uk/news/science/origins-life-ponds-organisms-earth-age-study-a7978906.html|title=Life first emerged in 'warm little ponds' almost as old as the Earth itself – Charles Darwin's famous idea backed by new scientific study|last=Johnston|first=Ian|date=2 October 2017|work=[[The Independent]]|accessdate=2 October 2017}}</ref>
-As for life on land, in 2019 scientists reported the discovery of a [[fossil]]ized [[fungus]], named ''[[Ourasphaira giraldae]]'', in the [[Northern Canada|Canadian Arctic]], that may have grown on land a billion years ago, well before [[plant]]s were living on land.<ref name="NYT-20190522">{{cite news|url=https://www.nytimes.com/2019/05/22/science/fungi-fossils-plants.html|title=How Did Life Arrive on Land? A Billion-Year-Old Fungus May Hold Clues – A cache of microscopic fossils from the Arctic hints that fungi reached land long before plants.|last=Zimmer|first=Carl|date=22 May 2019|work=[[The New York Times]]|accessdate=23 May 2019|authorlink=Carl Zimmer}}</ref><ref name="NAT-20190522">{{cite journal|last1=Loron|first1=Corentin C.|last2=François|first2=Camille|last3=Rainbird|first3=Robert H.|last4=Turner|first4=Elizabeth C.|last5=Borensztajn|first5=Stephan|last6=Javaux|first6=Emmanuelle J.|date=22 May 2019|title=Early fungi from the Proterozoic era in Arctic Canada|journal=[[Nature (journal)|Nature]]|volume=570|issue=7760|pages=232–235|publisher=[[Springer Science+Business Media|Springer Science and Business Media LLC]]|doi=10.1038/s41586-019-1217-0|pmid=31118507|bibcode=2019Natur.570..232L|issn=0028-0836}}</ref><ref name="Ars Technica 2019">{{cite web|url=https://arstechnica.com/science/2019/05/billion-year-old-fossils-may-be-early-fungus/|title=Billion-year-old fossils may be early fungus|last=Timmer|first=John|date=22 May 2019|website=[[Ars Technica]]|access-date=23 May 2019}}</ref> In July 2018, scientists reported that the earliest life on land may have been [[bacteria]] 3.22 billion years ago.<ref name="NG-20180723">{{cite journal|author=Homann, Martin|display-authors=et al.|date=23 July 2018|title=Microbial life and biogeochemical cycling on land 3,220 million years ago|journal=[[Nature Geoscience]]|volume=11|issue=9|pages=665–671|doi=10.1038/s41561-018-0190-9|bibcode=2018NatGe..11..665H}}</ref> In May 2017, evidence of microbial [[Evolutionary history of life#Colonization of land|life on land]] may have been found in 3.48 billion-year-old [[geyserite]] in the [[Pilbara Craton]] of Western Australia.<ref name="PO-20170509">{{cite news|url=https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html|title=Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks|author=Staff|date=9 May 2017|work=[[Phys.org]]|accessdate=13 May 2017}}</ref><ref name="EA-20190926">{{cite news |author=University of New South Wales |title=Earliest signs of life: Scientists find microbial remains in ancient rocks |url=https://www.eurekalert.org/pub_releases/2019-09/uons-eso092519.php |date=26 September 2019 |work=[[EurekAlert!]] |accessdate=27 September 2019 |author-link=University of New South Wales }}</ref>
+As for life on land, in 2019 scientists reported the discovery of a [[fossil]]ized [[fungus]], named ''[[Ourasphaira giraldae]]'', in the [[Northern Canada|Canadian Arctic]], that may have grown on land a billion years ago, well before [[plant]]s were living on land.<ref name="NYT-20190522">{{cite news|url=https://www.nytimes.com/2019/05/22/science/fungi-fossils-plants.html|title=How Did Life Arrive on Land? A Billion-Year-Old Fungus May Hold Clues – A cache of microscopic fossils from the Arctic hints that fungi reached land long before plants.|last=Zimmer|first=Carl|date=22 May 2019|work=[[The New York Times]]|accessdate=23 May 2019|authorlink=Carl Zimmer}}</ref><ref name="NAT-20190522">{{cite journal|last1=Loron|first1=Corentin C.|last2=François|first2=Camille|last3=Rainbird|first3=Robert H.|last4=Turner|first4=Elizabeth C.|last5=Borensztajn|first5=Stephan|last6=Javaux|first6=Emmanuelle J.|date=22 May 2019|title=Early fungi from the Proterozoic era in Arctic Canada|journal=[[Nature (journal)|Nature]]|volume=570|issue=7760|pages=232–235|publisher=[[Springer Science+Business Media|Springer Science and Business Media LLC]]|doi=10.1038/s41586-019-1217-0|pmid=31118507|bibcode=2019Natur.570..232L|s2cid=162180486|issn=0028-0836}}</ref><ref name="Ars Technica 2019">{{cite web|url=https://arstechnica.com/science/2019/05/billion-year-old-fossils-may-be-early-fungus/|title=Billion-year-old fossils may be early fungus|last=Timmer|first=John|date=22 May 2019|website=[[Ars Technica]]|access-date=23 May 2019}}</ref> In July 2018, scientists reported that the earliest life on land may have been [[bacteria]] 3.22 billion years ago.<ref name="NG-20180723">{{cite journal|author=Homann, Martin|display-authors=et al.|date=23 July 2018|title=Microbial life and biogeochemical cycling on land 3,220 million years ago|journal=[[Nature Geoscience]]|volume=11|issue=9|pages=665–671|doi=10.1038/s41561-018-0190-9|bibcode=2018NatGe..11..665H|s2cid=134935568}}</ref> In May 2017, evidence of microbial [[Evolutionary history of life#Colonization of land|life on land]] may have been found in 3.48 billion-year-old [[geyserite]] in the [[Pilbara Craton]] of Western Australia.<ref name="PO-20170509">{{cite news|url=https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html|title=Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks|author=Staff|date=9 May 2017|work=[[Phys.org]]|accessdate=13 May 2017}}</ref><ref name="EA-20190926">{{cite news |author=University of New South Wales |title=Earliest signs of life: Scientists find microbial remains in ancient rocks |url=https://www.eurekalert.org/pub_releases/2019-09/uons-eso092519.php |date=26 September 2019 |work=[[EurekAlert!]] |accessdate=27 September 2019 |author-link=University of New South Wales }}</ref>
 In January 2018, a study found that 4.5 billion-year-old [[meteorite]]s found on Earth contained [[Water#Liquid water|liquid water]] along with [[Abiogensis|prebiotic]] [[Organic compound|complex organic substances]] that may be ingredients for [[life]].<ref name="SA-20180110">{{cite journal |authors=Chan, Queenie H. S.|display-authors=etal|title=Organic matter in extraterrestrial water-bearing salt crystals |date=10 January 2018 |journal=[[Science Advances]] |volume=4 |pages=eaao3521|number=1, eaao3521 |doi=10.1126/sciadv.aao3521 |pmid=29349297|pmc=5770164|bibcode=2018SciA....4O3521C }}</ref><ref name="EA-20180110">{{cite news |author=Staff, Lawrence Berkeley National laboratory |title=Ingredients for life revealed in meteorites that fell to Earth – Study, based in part at Berkeley Lab, also suggests dwarf planet in asteroid belt may be a source of rich organic matter |url=https://www.eurekalert.org/pub_releases/2018-01/dbnl-ifl010918.php |date=10 January 2018 |newspaper=[[American Association for the Advancement of Science|AAAS – EurekAlert]] |accessdate=11 January 2018}}</ref>
@@ Line 35: / Line 35: @@
 </gallery>
 <gallery mode="packed" heights="130">
-File:Runzelmarken.jpg|[[Sediment|Wrinkled Kinneyia-type sedimentary structures]] formed beneath cohesive [[microbial mat]]s in [[Intertidal zone|peritidal zones]].<ref name=Porada2008>{{cite journal|author=Porada H. |author2=Ghergut J. |author3=Bouougri El H. |year=2008 |title=Kinneyia-Type Wrinkle Structures&nbsp;– Critical Review And Model Of Formation. |journal=[[PALAIOS]] |volume=23 |pages=65–77 |doi=10.2110/palo.2006.p06-095r |issue=2|bibcode=2008Palai..23...65P }}</ref>
+File:Runzelmarken.jpg|[[Sediment|Wrinkled Kinneyia-type sedimentary structures]] formed beneath cohesive [[microbial mat]]s in [[Intertidal zone|peritidal zones]].<ref name=Porada2008>{{cite journal|author=Porada H. |author2=Ghergut J. |author3=Bouougri El H. |year=2008 |title=Kinneyia-Type Wrinkle Structures&nbsp;– Critical Review And Model Of Formation. |journal=[[PALAIOS]] |volume=23 |pages=65–77 |doi=10.2110/palo.2006.p06-095r |issue=2|bibcode=2008Palai..23...65P |s2cid=128464944 }}</ref>
 File:Kinneyia Grimsby Silurian Niagara Gorge.jpg|[[Microbial mat|''Kinneyia''-like structure]] in the [[Grimsby Formation|Grimsby Formation (Silurian)]] exposed in [[Niagara Gorge|Niagara Gorge, NY]].
 </gallery>

v t e Origin of life
History of research	Panspermia (5th century BC) Spontaneous generation (4th century BC) Primordial soup (19th century)
Prebiotic synthesis	Pseudo-panspermia Miller–Urey experiment Formamide-based prebiotic chemistry Alternative abiogenesis scenarios
Protocells	GADV-protein world Clay hypothesis Iron–sulfur world Primordial sandwich PAH world Peptide-RNA world Quasispecies model RNA world
Earliest organisms	Earliest known life forms Last universal common ancestor (LUCA)
Research	Astrobiology Paleobiology

v t e Evolutionary biology
Introduction Outline Timeline of evolution History of life Index
Evolution	Abiogenesis Adaptation Adaptive radiation Altruism Cheating Reciprocal Baldwin effect Cladistics Coevolution Mutualism Common descent Convergence Divergence Earliest known life forms Evidence of evolution Evolutionary arms race Evolutionary pressure Exaptation Extinction Event Homology Last universal common ancestor Macroevolution Microevolution Mismatch Non-adaptive radiation Origin of life Panspermia Parallel evolution Signalling theory Handicap principle Speciation Species Species complex Taxonomy Unit of selection Gene-centered view of evolution
Population genetics	Artificial selection Biodiversity Evolutionarily stable strategy Fisher's principle Fitness Inclusive Gene flow Genetic drift Kin selection Parental investment Parent–offspring conflict Mutation Population Natural selection Sexual dimorphism Sexual selection Mate choice Social selection Trivers–Willard hypothesis Variation
Development	Canalisation Evolutionary developmental biology Genetic assimilation Inversion Modularity Phenotypic plasticity
Of taxa	Bacteria Birds origin Brachiopods Molluscs Cephalopods Dinosaurs Fish Fungi Insects butterflies Life Mammals cats canids wolves dogs hyenas dolphins and whales horses Kangaroos primates humans lemurs sea cows Plants pollinator-mediated Reptiles Spiders Tetrapods Viruses
Of organs	Cell DNA Flagella Eukaryotes symbiogenesis chromosome endomembrane system mitochondria nucleus plastids In animals eye hair auditory ossicle nervous system brain
Of processes	Aging Death Programmed cell death Avian flight Biological complexity Cooperation Color vision in primates Emotion Empathy Ethics Eusociality Immune system Metabolism Monogamy Morality Mosaic evolution Multicellularity Sexual reproduction Gamete differentiation/sexes Life cycles/nuclear phases Mating types Meiosis Sex-determination Snake venom
Tempo and modes	Gradualism/Punctuated equilibrium/Saltationism Micromutation/Macromutation Uniformitarianism/Catastrophism
Speciation	Allopatric Anagenesis Catagenesis Cladogenesis Cospeciation Ecological Hybrid Non-ecological Parapatric Peripatric Reinforcement Sympatric
History	Renaissance and Enlightenment Transmutation of species David Hume Dialogues Concerning Natural Religion Charles Darwin On the Origin of Species History of paleontology Transitional fossil Blending inheritance Mendelian inheritance The eclipse of Darwinism Neo-Darwinism Modern synthesis History of molecular evolution Extended evolutionary synthesis
Philosophy	Darwinism Alternatives Catastrophism Lamarckism Orthogenesis Mutationism Saltationism Structuralism Spandrel Theistic Vitalism Teleology in biology
Related	Biogeography Ecological genetics Evolutionary medicine Group selection Cultural evolution Cultural group selection Dual inheritance theory Hologenome theory of evolution Missing heritability problem Molecular evolution Astrobiology Phylogenetics Tree Polymorphism Protocell Systematics Transgenerational epigenetic inheritance
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