Editing Last universal common ancestor (section)

== Historical background ==

{{further|Tree of life (biology)}}

[[File:Darwin Tree 1837.png|thumb|upright|A [[Tree of life (biology)|tree of life]], like this one from [[Charles Darwin]]'s notebooks {{circa|July&nbsp;1837}}, implies a single common ancestor at its root (labelled "1").]]

A [[phylogenetic tree]] directly portrays the idea of [[evolution]] by [[common descent|descent from a single ancestor]]<!-- at the root of the tree-->.<ref name="Gregory 2008">{{cite journal |last=Gregory |first=T. Ryan |year=2008 |title=Understanding evolutionary trees |journal=Evolution: Education and Outreach |volume=1 |issue=2 |pages=121–137 |doi=10.1007/s12052-008-0035-x|s2cid=15488906 |doi-access=free }}</ref> An early tree of life was sketched by [[Jean-Baptiste Lamarck]] in his ''[[Philosophie zoologique]]'' in 1809.<ref>{{cite book |last=Lamarck |first=Jean Baptiste Pierre Antoine de Monet de |author-link=Jean-Baptiste Lamarck |title=Philosophie zoologique |orig-date=1809 |year=1994 |location=Paris |page=737 <!-- |oclc=31599154 --> |url=https://ia801004.us.archive.org/28/items/LamarckPZ/Lamarck_PZ.pdf }}</ref><ref>{{cite journal |last=Noble |first=Denis |author-link=Denis Noble |date=1 July 2020 |title=Editorial: Charles Darwin, Jean-Baptiste Lamarck, and 21st&nbsp;century arguments on the fundamentals of biology |journal=Progress in Biophysics and Molecular Biology |volume=153 |pages=1–4 |doi=10.1016/j.pbiomolbio.2020.02.005 |pmid=32092299 |s2cid=211475380 |url=https://www.sciencedirect.com/science/article/pii/S0079610720300134 |access-date=2022-12-23 |archive-date=1 March 2022 |archive-url=https://web.archive.org/web/20220301193402/https://www.sciencedirect.com/science/article/pii/S0079610720300134 |url-status=live }}</ref> [[Charles Darwin]] more famously proposed the theory of universal common descent through an evolutionary process in his book ''[[On the Origin of Species]]'' in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed."<ref name="Darwin 1859">{{cite book |last=Darwin |first=Charles |author-link=Charles Darwin |year=1859 |title=The Origin of Species by Means of Natural Selection |pages=484, 490<!-- original pages --> |publisher=[[John Murray (publishing house)|John Murray]] |url=http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=484 |access-date=8 October 2022 |archive-date=8 October 2022 |archive-url=https://web.archive.org/web/20221008150204/http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=484 |url-status=live }}</ref> The last sentence of the book begins with a restatement of the hypothesis:
{{blockquote|text=There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one&nbsp;...|source=<ref name="Darwin 1859"/>}}

The term "last universal common ancestor" or "LUCA" was first used in the 1990s for such a primordial organism.<ref>{{cite thesis |last=Wikham |first=Gene Stephen |date=March 1995 |title=The molecular phylogenetic analysis of naturally occurring hyperthermophilic microbial communities |publisher=[[Indiana University]] |degree=PhD |page=4}} {{ProQuest|304192982}}</ref><ref name="Forterre 1997 pp. 764–770">{{cite journal |last=Forterre |first=Patrick |year=1997 |title=Archaea: What can we learn from their sequences? |journal=Current Opinion in Genetics & Development |volume=7 |issue=6 |pages=764–770 |doi=10.1016/s0959-437x(97)80038-x|pmid=9468785 }}</ref><ref>{{cite book |last1=Koonin |first1=Eugene V. |author1-link=Eugene Koonin |last2=Galperin |first2=Michael Y. |year=2003 |title=Sequence - Evolution - Function: Computational approaches in comparative genomics |location=Boston, MA |publisher=Kluwer |isbn=978-1-4757-3783-7 |page=252 |oclc=55642057 }}</ref>