Common descent: Difference between revisions

{{shortShort description|Characteristic of a group of organisms with a common ancestor}}

{{for For|use of the term in linguistics and philology |Comparative method (linguistics) |Historical linguistics |Proto-language |Textual criticism}}

{{redirect Redirect|Common ancestor |use of the term in graph theory |Lowest common ancestor}}

'''Common descent''' is a concept in [[evolutionary biology]] applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonly referred to as the [[last universal common ancestor]] (LUCA) of all [[life]] on [[Earth]].<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=2016-07-25|title=The physiology and habitat of the last universal common ancestor|url=https://www.nature.com/articles/nmicrobiol2016116|journal=Nature Microbiology|language=en|volume=1|issue=9|page=16116|doi=10.1038/nmicrobiol.2016.116|pmid=27562259|s2cid=2997255|issn=2058-5276}}</ref><ref>{{Cite journal|last1=Forterre|first1=Patrick|last2=Gribaldo|first2=Simonetta|last3=Brochier|first3=Céline|date=October 2005|title=[Luca: the last universal common ancestor]|journal=Médecine/Sciences|volume=21|issue=10|pages=860–865|doi=10.1051/medsci/20052110860|issn=0767-0974|pmid=16197904|doi-access=free}}</ref><ref name="theobald">{{cite journal |last=Theobald |first=Douglas L. |date=13 May 2010 |title=A formal test of the theory of universal common ancestry |journal=[[Nature (journal)|Nature]] |volume=465 |issue=7295 |pages=219–222 |doi=10.1038/nature09014 |pmid=20463738|bibcode=2010Natur.465..219T |s2cid=4422345 }}</ref><ref name="steel">{{cite journal |last1=Steel |first1=Mike |author1-link=Mike Steel (mathematician) |last2=Penny |first2=David |date=13 May 2010 |title=Origins of life: Common ancestry put to the test |journal=Nature |volume=465 |issue=7295 |pages=168–169 |doi=10.1038/465168a |pmid=20463725|bibcode=2010Natur.465..168S |s2cid=205055573 |doi-access=free }}</ref>

Common descent is an effect of [[speciation]], in which multiple species derive from a single ancestral population. The more recent the ancestral population two species have in common, the more closely are they related. The most recent common ancestor of all currently living organisms is the last universal ancestor,<ref name="theobald" /> which lived about [[Timeline of the evolutionary history of life|3.9 billion years ago]].<ref>{{cite journal |last=Doolittle |first=W. Ford |author-link=Ford Doolittle |date=February 2000 |title=Uprooting the Tree of Life |url=http://shiva.msu.montana.edu/courses/mb437_537_2004_fall/docs/uprooting.pdf |journal=[[Scientific American]] |volume=282 |issue=2 |pages=90–95 |doi=10.1038/scientificamerican0200-90 |pmid=10710791 |archive-url=https://web.archive.org/web/20060907081933/http://shiva.msu.montana.edu/courses/mb437_537_2004_fall/docs/uprooting.pdf |archive-date=2006-09-07 |access-date=2015-11-22|bibcode=2000SciAm.282b..90D }}</ref><ref>{{cite journal |last1=Glansdorff |first1=Nicolas |author2=Ying Xu |last3=Labedan |first3=Bernard |date=9 July 2008 |title=The Last Universal Common Ancestor: emergence, constitution and genetic legacy of an elusive forerunner |journal=[[Biology Direct]] |volume=3 |page=29 |doi=10.1186/1745-6150-3-29 |pmc=2478661 |pmid=18613974 |doi-access=free }}</ref> The two earliest pieces of evidence for life on Earth are [[graphite]] found to be [[Biogenic substance|biogenic]] in 3.7 billion-year-old [[metasedimentary rock]]s discovered in western [[Greenland]]<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. |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}}</ref> and [[microbial mat]] [[fossil]]s found in 3.48 billion-year-old [[sandstone]] discovered in [[Western Australia]].<ref name="AP-20131113">{{cite news |last=Borenstein |first=Seth |date=13 November 2013 |title=Oldest fossil found: Meet your microbial mom |url=https://www.yahoo.com/news/oldest-fossil-found-meet-microbial-mom-223338964.html |publisher=[[Yahoo News]] |agency=[[Associated Press]] |access-date=2015-11-22 |archive-date=2019-11-10 |archive-url=https://web.archive.org/web/20191110152138/https://www.yahoo.com/news/oldest-fossil-found-meet-microbial-mom-223338964.html |url-status=dead }}</ref><ref name="AST-20131108">{{cite journal |last1=Noffke |first1=Nora |author1-link=Nora Noffke |last2=Christian |first2=Daniel |last3=Wacey |first3=David |last4=Hazen |first4=Robert M. |author-link4=Robert Hazen |date=16 December 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 |doi=10.1089/ast.2013.1030 |pmc=3870916 |pmid=24205812|bibcode=2013AsBio..13.1103N }}</ref> All currently living organisms on Earth share a common [[Genetics|genetic]] heritage, though the suggestion of substantial [[horizontal gene transfer]] during early evolution has led to questions about the [[monophyly]] (single ancestry) of life.<ref name="theobald" /> 6,331 groups of [[gene]]s common to all living animals have been identified; these may have arisen from a single [[Animal#Phylogeny|common ancestor]] that lived [[Cryogenian|650 million years ago]] in the [[Precambrian]].<ref name="NYT-20180504" /><ref name="NC-20150430" />

{{quoteBlockquote|There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. One point to note is Kamran is no way related to Ian's dog.<ref name="origin_490">{{harvnb|Darwin|1859|p=490}}</ref>}}

The idea that all living things (including things considered non-living by science) are related is a recurring theme in many indigenous worldviews across the world.<ref>{{Cite webnews|last=Staff|first=I. C. T.|title=We Are All Related: Indigenous Knowledge Reaffirmed by Digitized Tree of Life|url=https://indiancountrytoday.com/archive/we-are-all-related-indigenous-knowledge-reaffirmed-by-digitized-tree-of-life|access-date=2021-05-05|websitenewspaper=IndianIct CountryNews|date=13 September 2018 Today|language=en}}</ref> Later on, in the 1740s, the French [[mathematician]] [[Pierre Louis Maupertuis]] arrived at the idea that all organisms had a common ancestor, and had diverged through random variation and [[natural selection]].<ref>{{harvnb |Crombie |Hoskin |1970 |pp=[https://books.google.com/books?id=OOgzAAAAIAAJ&pg=PA62&dq=Maupertuis+%22for+the+first+time%22&cdpg=1#v=onepage&q=Maupertuis%20%22for%20the%20first%20time%22&f=falsePA62 62–63]}}</ref><ref>{{harvnb |Treasure |1985 |p=142}}</ref> In ''Essai de cosmologie'' (1750), Maupertuis noted:

In 1790, the philosopher [[Immanuel Kant]] wrote in ''Kritik der Urteilskraft'' (''[[Critique of Judgment]]'') that the similarity{{efn|Now called [[Homology (biology)|homology]].}} of animal forms implies a common original type, and thus a common parent.<ref>{{harvnb |Kant |1987 |p=[https://books.google.com/books?id=y5wQD-ioaUUC&pg=PA304&dq=Critique+of+Judgment+%22original+mother%22&cdpg=1#v=onepage&q=&f=falsePA304 304]}}: "Despite all the variety among these forms, they seem to have been produced according to a common archetype, and this analogy among them reinforces our suspicion that they are actually akin, produced by a common original mother."</ref>

<blockquote>No reliable observation has ever been found to contradict the general notion of common descent. It should come as no surprise, then, that the scientific community at large has accepted evolutionary descent as a historical reality since Darwin’sDarwin's time and considers it among the most reliably established and fundamentally important facts in all of science.<ref>{{Cite journal | doi=10.1007/s12052-007-0001-z|title = Evolution as Fact, Theory, and Path| journal=Evolution: Education and Outreach| volume=1| pages=46–52|year = 2008|last1 = Gregory|first1 = T. Ryan|doi-access=free}}</ref></blockquote>

All known forms of life are based on the same fundamental biochemical organization: genetic information encoded in [[DNA]], transcribed into [[RNA]], through the effect of [[protein]]- and RNA-[[enzyme]]s, then translated into proteins by (highly similar) [[ribosome]]s, with [[Adenosine triphosphate|ATP]], [[Nicotinamide adenine dinucleotide phosphate|NADPH]] and others as energy sources. Analysis of small sequence differences in widely shared substances such as [[cytochrome c]] further supports universal common descent.<ref name=Knight>{{cite journal |last1=Knight |first1=Robin |last2=Freeland |first2=Stephen J. |last3=Landweber |first3=Laura F. |date=January 2001 |title=Rewiring the keyboard: evolvability of the genetic code |journal=[[Nature Reviews Genetics]] |volume=2 |issue=1 |pages=49–58 |doi=10.1038/35047500 |pmid=11253070 |s2cid=12267003 }}</ref> Some 23 proteins are found in all organisms, serving as [[enzyme]]s carrying out core functions like DNA replication. The fact that only one such set of enzymes exists is convincing evidence of a single ancestry.<ref name="theobald" /><ref name="Than2010">{{cite magazine |last1=Than|first1=Ker |title=All Species Evolved From Single Cell, Study Finds |url=https://news.nationalgeographic.com/news/2010/05/100513-science-evolution-darwin-single-ancestor/ |archive-url=https://web.archive.org/web/20100515123853/http://news.nationalgeographic.com/news/2010/05/100513-science-evolution-darwin-single-ancestor |url-status=dead |archive-date=May 15, 2010 |magazine=National Geographic |access-date=22 November 2017 |date=14 May 2010}}</ref> 6,331 [[gene]]s common to all living animals have been identified; these may have arisen from a single [[Animal#Phylogeny|common ancestor]] that lived [[Cryogenian|650 million years ago]] in the [[Precambrian]].<ref name="NYT-20180504">{{cite news |last=Zimmer |first=Carl |author-link=Carl Zimmer |title=The Very First Animal Appeared Amid an Explosion of DNA |url=https://www.nytimes.com/2018/05/04/science/first-animal-genes-evolution.html |archive-url=https://ghostarchive.org/archive/20220101/https://www.nytimes.com/2018/05/04/science/first-animal-genes-evolution.html |archive-date=2022-01-01 |url-access=limited |date=4 May 2018 |work=[[The New York Times]] |access-date=4 May 2018 }}{{cbignore}}</ref><ref name="NC-20150430">{{cite journal |last1=Paps |first1=Jordi |last2=Holland |first2=Peter W. H. |title=Reconstruction of the ancestral metazoan genome reveals an increase in genomic novelty |date=30 April 2018 |journal=[[Nature Communications]] |volume=9 |pages=1730 |number=1730 (2018) |doi=10.1038/s41467-018-04136-5 |pmid=29712911 |pmc=5928047 |bibcode=2018NatCo...9.1730P }}</ref>

The way that [[Genetic code|codon]]s (DNA triplets) are mapped to [[amino acid]]s seems to be strongly optimised. Richard Egel argues that in particular the [[hydrophobic]] (non-polar) side-chains are well organised, suggesting that these enabled the earliest organisms to create [[peptide]]s with water-repelling regions able to support the essential electron exchange ([[redox]]) reactions for energy transfer.<ref name=Egel>{{cite journal |last1=Egel |first1=Richard |title=Primal Eukaryogenesis: On the Communal Nature of Precellular States, Ancestral to Modern Life |journal=Life |date=March 2012 |volume=2 |issue=1 |pages=170–212 |doi=10.3390/life2010170 |pmc=4187143 |pmid=25382122|bibcode=2012Life....2..170E |doi-access=free }}</ref>

Biologists often{{quantify|date=March 2018}} point to the universality of many aspects of cellular life as supportive evidence to the more compelling evidence listed above. These similarities include the energy carrier [[adenosine triphosphate]] (ATP), and the fact that all amino acids found in proteins are [[Chirality (chemistry)#In biochemistry|left-handed]]. It is, however, possible that these similarities resulted because of the [[Laws of science|laws of physics and chemistry]] - rather than through universal common descent - and therefore resulted in convergent evolution. In contrast, there is evidence for homology of the central subunits of [[ATPase#Transmembrane ATP synthases|Transmembranetransmembrane ATPases]] throughout all living organisms, especially how the rotating elements are bound to the membrane. This supports the assumption of a LUCA as a cellular organism, although primordial membranes may have been semipermeable and evolved later to the membranes of modern bacteria, and on a second path to those of modern archaea also.<ref>

If early organisms had been driven by the same environmental conditions to [[Convergent evolution|evolve similar biochemistry convergently]], they might independently have acquired similar genetic sequences. Theobald's "formal test" was accordingly criticised by Takahiro Yonezawa and colleagues<ref>{{cite journal |last1=Yonezawa |first1=Takahiro |last2=Hasegawa |first2=Masami |title=Was the universal common ancestry proved? |date=16 December 2010 |journal=Nature |volume=468 |issue=7326 |page=E9 |doi=10.1038/nature09482 |pmid=21164432|bibcode=2010Natur.468E...9Y |s2cid=4318346 |doi-access=free }}</ref> for not including consideration of convergence. They argued that Theobald's test was insufficient to distinguish between the competing hypotheses. Theobald has defended his method against this claim, arguing that his tests distinguish between phylogenetic structure and mere sequence similarity. Therefore, Theobald argued, his results show that "real universally [[Conserved sequence|conserved]] proteins are [[sequence homology|homologous]]."<ref>{{cite journal |last=Theobald |first=Douglas L. |date=16 December 2010 |title=Theobald reply |journal=Nature |volume=468 |issue=7326 |page=E10 |doi=10.1038/nature09483|bibcode=2010Natur.468E..10T |s2cid=4317014 |doi-access=free }}</ref><ref>{{cite journal |last=Theobald |first=Douglas L. |date=24 November 2011 |title=On universal common ancestry, sequence similarity, and phylogenetic structure: The sins of P-values and the virtues of Bayesian evidence |journal=Biology Direct |volume=6 |issue=1 |page=60 |doi=10.1186/1745-6150-6-60 |pmc=3314578 |pmid=22114984 |doi-access=free }}</ref>

[[Category:LastMost recent common ancestors]]