Talk:Last universal common ancestor/Archive 1

"Probabilities"

I don't have access to the cited Science News article, but numbers as large as 10^2860 are ridiculous. This must be a typo. Mphelbert (talk) 18:27, 24 July 2010 (UTC)

I'd have thought so, but I have access to the article through my university and it does indeed say "Therefore, UCA is at least 10^(2,860) times more probable than the closest competing hypothesis."

Quite an incredible number, but it's what's in the paper.

These numbers are correct. There are many places in Statistical Mechanics, Quantum Mechanics, and other "hard" sciences where such probabilities show up. These numbers are from a paper in Nature, which is arguably the most prestigious science journal in the world and they are correct.

138.253.48.109 (talk) 11:37, 23 August 2010 (UTC)

Steel, Mike; Penny, David (13 May 2010). "Origins of life: Common ancestry put to the test". Nature. 465 (7295). London: Macmillan Publishers Limited: 168–169. doi:10.1038/465168a. ISSN 0028-0836.{{cite journal}}: CS1 maint: date and year (link)

Theobald, Douglas L. (13 May 2010). "A formal test of the theory of universal common ancestry". Nature. 465 (7295). London: Macmillan Publishers Limited: 219–222. doi:10.1038/nature09014. ISSN 0028-0836.{{cite journal}}: CS1 maint: date and year (link)

I do not know why the two Nature citations were removed, but I put them in originally, and have restored them.

Nick Beeson (talk) 11:39, 6 April 2011 (UTC)

Falsified material in this article.

Concerning this abstract/paper by Douglas L. Theobald (Theobald DL on his paper) which is cited in the Wikipedia article at http://en.wikipedia.org/wiki/Universal_ancestor

> "Nature. 2010 May 13; 465(7295):219-22.
> A formal test of the theory of universal common ancestry.
> Theobald DL.
> Department of Biochemistry, Brandeis University, Waltham,
> Massachusetts 01778, USA. dtheob...@brandeis.edu
> Comment in:
>     * Nature. 2010 May 13;465(7295):168-9.
> Abstract
> Universal common ancestry (UCA) is a central pillar of modern
> evolutionary theory. As first suggested by Darwin, the theory of UCA
> posits that all extant terrestrial organisms share a common genetic
> heritage, each being the genealogical descendant of a single species
> from the distant past. ***The classic evidence for UCA, although
> massive, is largely restricted to 'local' common ancestry-for example,
> of specific phyla rather than the entirety of life-and has yet to
> fully integrate the recent advances from modern phylogenetics and
> probability theory. Although UCA is widely assumed, it has rarely been
> subjected to formal quantitative testing,*** and this has led to
> critical commentary emphasizing the intrinsic technical difficulties
> in empirically evaluating a theory of such broad scope. Furthermore,
> several researchers have proposed that early life was characterized by
> rampant horizontal gene transfer, ****leading some to question the
> monophyly of life.**** Here I provide the FIRST, to my knowledge,
> formal, fundamental test of UCA, without assuming that sequence
> similarity implies genetic kinship. I test UCA by applying model
> selection theory to molecular phylogenies, focusing on a set of
> ubiquitously conserved proteins that are proposed to be orthologous.
> Among a wide range of biological models involving the independent
> ancestry of major taxonomic groups, the model selection tests are
> found to overwhelmingly support UCA irrespective of the presence of
> horizontal gene transfer and symbiotic fusion events. These results
> provide powerful statistical evidence corroborating the monophyly of
> all known life.
> PMID: 20463738 [PubMed - indexed for MEDLINE]"

> From - http://www.ncbi.nlm.nih.gov/pubmed/20463738 (fromhttp://en.wikipedia.org/wiki/Evolution)

Look how in the following that two Wikipedia contributors (Mike Steel and David Penny) have falsified data from the SAME paper/abstract (abstract by Theobald, DL, also known as Douglas L. Theobald) that I cited above, crediting *themselves* with writing a book or something or other (likely a letter to the magazine that printed Theobald's paper) on the subject of the article/paper on the SAME DATE as the article/paper and linking to Theobald's paper.

From Wikipedia's article Last Common Ancestor at - http://en.wikipedia.org/wiki/Universal_ancestor - last updated 17 Sept. 2010

David Penny and Mike Steel write (notice the quoted material is a partial sentence only and IS NOT CONTAINED in the abstract/paper by Theobald, which is at the top of this post):

"There is strong quantitative support, by a formal test"[1] for the theory that all living organisms on Earth are descended from a common ancestor.[4]"

Note who their sources for this statement are: themselves (#4), and the paper/abstract I cited above (#1). And the PMID numbers in both #1 and #4 are links which lead to the same abstract/paper by Theobald.

1. ^ a b c d Theobald, Douglas L. (13 May 2010). "A formal test of the theory of universal common ancestry". Nature 465 (7295): 219–222. doi:10.1038/nature09014. PMID 20463738.

4. ^ a b Steel, Mike; Penny, David (13 May 2010). "Origins of life: Common ancestry put to the test". Nature 465 (7295): 168–169. doi: 10.1038/465168a. PMID 2046372

Linda 444 (talk) 19:07, 27 September 2010 (UTC)

Linda 444,

I am sorry that you find this suspicious, but there is nothing the least suspicious about this.

It is common in the two most prestigious scientific journals in the world: Nature, and Science. They both have a "commentary" section where the publish "editorials" explaining articles published later in the same issue. The goal of editorials is to:

• inform the educated layman why an article is important;
• show how it fits into the research goals of a field; and
• discuss its impact on other fields.

These editorials always cite the article in the same issue of the journal, and often cite the editorial author's own research. The reader is expected to trust the journal editor to have chosen an expert in the field. who will present a neutral point of view. The readers know the author's work is impacted by the article under discussion, and that they will therefore cite their own work.

I cited the commentary precisely because it tells the audience why the research is important in words Wikipedia readers can be expected to understand.

Nick Beeson (talk) 12:56, 6 April 2011 (UTC)

Problems with Some "Evidence"

This needs to be updated with respect to some of the evidence points given in the "Evidence of universal common descent". There are elements of this that, while evidentiary, is not true of all current life on earth.

Examples include:

• Re the repeated statement that "only 20 amino acids are used": Human DNA codes for 22 amino acids (though, admittedly, only 20 of those are directly coded by the codons) and those 22 acids can all be used in proteins. It might be better to say that the same common 20 amino acids are used, rather than "only".
• DNA is, indeed, always composed of four nucleotides, but some forms of life substitute one of the nucleotides for a different one. That is, not all life uses the combination "(deoxyadenosine, deoxycytidine, deoxythymidine and deoxyguanosine)"; some life uses a DNA in which one of these is replaced by some other deoxynucleotide.
• I would have to dig for this, but I think I read that not all life uses the glycolysis pathway. Some of the archaea H₂S, if I remember correctly, do not implement this pathway.

There is plenty of evidence still, of the last universal ancestor; this is just a matter of correcting the article qualifications to be more accurate in view of later discoveries.

CoyneT ^talk

Good points. Please don't be shy about editing, though. If you see something that needs to be corrected, be bold. -Thibbs (talk) 19:35, 29 May 2010 (UTC)

CoyneT, let's see a source regarding your claim of human DNA coding for synthases to make non-LUCA amino acids. (They must be directly encoded by the codons to be "coded for" in the DNA, otherwise a synthase enzyme for the amino acid in question would have to be encoded.) I'm well aware that plants make extra amino acids as a defense mechanism, but I'm not so sure we make amino acids outside the main 20. The Mysterious El Willstro (talk) 03:37, 25 March 2012 (UTC)

Arbitrary choice of codons?

This article states that there was an arbitrary choice of codon patterning. I am not an expert, but last I checked, there was evidence that each codon tends to be more attracted to its amino acid in solution than to any other. Also, to describe the universal ancestor as already having 3-base codons etc should be cited in my opinion. Any such organism must have evolved from something simpler, or been put there by an intelligent designer. - Richard Cavell (talk) 12:11, 19 March 2011 (UTC)

There were simpler globules (I say "globules" because calling them "organisms" whatsoever is rather debatable) that existed before LUCA. LUCA has "Last" in its name for partly that very reason: It lived fairly late in the Abiogenesis Event. The Mysterious El Willstro (talk) 03:48, 25 March 2012 (UTC)

Cavalier-Smith phylogeny?!

I am baffled by the appearance of a phylogenitic tree based on cavalier-smith papers being presented as the accepted view of the tree of life. It is all but the accepted view. I find the Cavalier-smith papers very interesting and bold, but they must be read in context (the reviewers' comments on his biology direct paper spell it out). Molecular phylogeny may be wrong, but until the consensus is against it, it should be the main view presented. Putting together a cladogram requires a lot of effort and I do not want to summarily delete it, but in most scientific litterature LUCA is not a bacterium, but a bacterium/neomuran ancestor. Most papers that do claim it to be a bacterium place it in the Firmicutes and not with a basal phylum "Chloroflexi" (the phylum does not have a proper name and Cavalier-Smith coined the term Chlorobacteria, but that is not how the system works another example why the papers require a pinch of salt). Therefore should this large tree be transfered elsewhere? --Squidonius (talk) 03:49, 1 August 2011 (UTC) Moved here for now: Phylogeny

References

This article is about phylogeny based on a controversial theory. For other phylogenies, see bacterial phyla.

LUCA

?Armatimonadetes (Candidate division OP10) Chlorobacteria1,2,3 (Green Non-sulfur or anoygenic photoheterotrophic Eubacteria) Deinococci1,2,3   Glycobacteria Cyanobacteria2,3 (Blue-green Algae/Bacteria)   Gracilicutes3 Spirochaetes (Spiral-shaped Eubacteria)   Sphingobacteria Gemmatimonas aurantiaca (DAP-less cell wall Eubacteria) Fibrobacter Chlorobi (Green Sulfur Eubacteria) Bacteroidetes   Exoflagellata   Planctobacteria ?'Candidatus Poribacter' Planctomycetes (Peptidoglycan-less Cell Wall Eubacteria) Chlamydiales Lentisphaerae (Candidate division vadinBE97) Verrucomicrobia ?Caldisericum exile (Candidate division OP5)   Geobacteria Acidobacteria   Ferrobacteria Chrysiogenaceae Nitrospiraceae Deferribacteres Thermodesulfobacteriaceae Aquificales Proteobacteria   Unibacteria ?Fusobacteriales3 Thermotogales Heliobacteriaceae   Posibacteria   Endobacteria Dictyoglomus Mollicutes (Cellwall-less Endobacteria) Teichobacteria   Actinobacteria ?Nostocoida limicola I♠ ?Candidatus Planktophila limnetica♠ ?Cathayosporangium alboflavum♠ ?Tonsillophilus suis♠ Rubrobacteridae Coriobacteriaceae Nitriliruptoridae Acidimicrobiales   Proteates ?Boyliae praeputiale♠ ?Frankia alni♠4,5,7 Acidothermus cellulolyticus4,5,7 Cryptosporangiaceae4 Nakamurellaceae4,5 Geodermatophilaceae4,5,7 Sporichthya4,5,6,7 Streptomyces5 Catenulisporiineae Kineosporiaceae5,7 Micrococcineae6 [incl. Actinomycetaceae, Bifidobacteriaceae] Streptosporangiineae5 Propionibacteriineae7 Jiangellaceae Actinocatenispora Micromonosporaceae7 Glycomycetaceae Thermomonospora chromogena5 Thermobispora bispora5 Pseudonocardiineae7 [incl. Actinopolyspora] Corynebacteriineae7 [incl. Mycobacteriales]   Neomura Archaeabacteria Eukaryota (Nucleic organisms)

Notes:
1 Eobacteria
2 Glidobacteria
3 Negibacteria
4 Frankiineae
5 Streptomycetes
6 Arthrobacteria
7 Arabobacteria (Neomura stem from within Arabobacteria)
8 Archaeobacteria
Eurybacteria = Selenobacteriales, Heliobacteriaceae, Fusobacteriales & Thermotogales
Aphragmabacteria = Mollicutes & Erysilothrichia
Terrabacteria: Chlorobacteri, Deinococci, Cyanobacteria, Endobacteria, Actinobacteria & ?Fusobacteria
Selabacteria: Terrabacteria & Hydrobacteria

♠ Strain found at the National Center for Biotechnology Information (NCBI) but has no standing with the Bacteriological Code (1990 and subsequent Revision) as detailed by List of Prokaryotic names with Standing in Nomenclature (LPSN) as a result of the following reasons:
• No pure culture isolated or available for Prokayotes.
• Not validly published because the effective publication only documents deposit of the type strain in a single recognized culture collection.
• Not approved and published by the International Journal of Systematic Biology or the International Journal of Systematic and Evolutionary Microbiology (IJSB/IJSEM).

That looks like it has enough sources to discuss it in the Article, although other possible phylogenies should be discussed as well. The Mysterious El Willstro (talk) 01:19, 30 April 2012 (UTC)

Auto-Archive

Let's start Auto-Archiving this Talk Page. The Mysterious El Willstro (talk) 01:45, 30 April 2012 (UTC)

Features Section

I removed two points from the features section. If people have objections to this, let's discuss it here :)

• All other properties of the organism were the result of protein functions.

This seems to me to be a fairly vague statement, which leaves it very open to interpretation by the reader. What does it mean by "all other" properties? Even given this ambiguity, I find it very hard to imagine how this could be true in any interpretation. Many properties of organisms depend, for instance, on the lipids in their membranes, something which certainly true for LUCA as well. Also, this statement disregards the importance of catalytic or otherwise functional RNAs, which were probably even more prominent in LUCA than in most modern organisms (where they are still very significant!) given that most of the original catalytic functions of the life were probably carried out by RNAs and later replaced by proteins. Anyways, I find this point uninformative at best and downright misleading at worst.

• Glucose could be used as a source of energy and carbon; only the D-isomer was used.

My problem here is not with the D-isomer, but rather with the assertion that LUCA metabolized glucose. While this is certainly possible, given the immense variety of metabolisms present in modern bacteria (which are discussed in the PNAS article currently cited as ref 8), LUCA's metabolism (or range of metabolisms) is likely not known with much certainty. Unless someone can find some sources suggesting that LUCA metabolized glucose, I think this statement is quite unfounded. A2soup (talk) 01:36, 4 May 2013 (UTC)

Religious Bias

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The information in the "Criticism" section can be broadly defined as "Creation Science." These are arguments commonly used to support the pre-conceived conclusion that humans evolved independently of all other organisms on earth. Basically, the author's position is that instead of there being ONE family tree for all life on earth, there are a bunch of different trees and that in some cases(particularly that of humans) the tree is simply linear. While the article should probably contain some general comment to the effect that there are some other non-trivial hypotheses about the exact path to our current biodiversity, it is NOT acceptable for non-NPOV theories outside sphere of accepted science to comrprise 60+% of the article. —The preceding unsigned comment was added by 167.83.10.20 (talk) 20:15, 11 April 2007 (UTC).

Let us PLEASE not get religious "criticisms" into this article. That should belong in Conservapedia. Let's keep it proper science on this page. — Preceding unsigned comment added by 149.172.153.15 (talk) 10:29, 22 November 2012 (UTC)

I am removing the "LUCA is refuted" paragraph, it's thinly disguised creationism. The somewhat relevant parts of it, about problems rooting the tree of life, are already addressed in the article via the section on gene transfer.

-Blueshifter 15:26, 29 April 2007 (UTC)

The criticism section smacks of creationist nonsense right from the first sentance. —Preceding unsigned comment added by 12.33.211.29 (talk • contribs) 09:56, 20 June 2007

It shouldn't automatically be dismissed as 'nonsense'. People need to be open to other viewpoints and interpretations of the scientific evidence. I do understand the rules of needing reliable/verified material for the wiki, though. But people still need to have more respect for other viewpoints. — Preceding unsigned comment added by 98.213.92.109 (talk • contribs) 05:06, 9 January 2012

Removed unsourced, weasely criticism section. There is no doubt some published scientific criticism - so find and cite it if the section is to be re-written. Vsmith 11:28, 20 June 2007 (UTC)

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"What we know" section created

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I created a paragraph that attempts to list all the properties shared by all independently living organisms (not viruses), based on the assumption that the LUA must also have had these properties. I had lots of fun doing this. It is clearly incomplete; be bold, improve it. Emmanuelm (talk) 16:15, 11 January 2008 (UTC)

It's very interesting, nice work. It would be better if you had a source, but I won't touch it. One thing struck me however: "almost all independently living organisms". Considering the scope of the LUA concept, "almost" has no place there. I've removed it, at the risk of being less exact(?) In this place however "almost" is a weasel word. But again, nice work. Piet | Talk 20:37, 15 January 2008 (UTC)

Thanks Piet. I added two references only; they were surprisingly difficult to find. Please help by finding more. Emmanuelm (talk) 17:00, 18 January 2008 (UTC)

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"Darwin's black box and the LUA" section created

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I added this paragraph. A bit weak, but I think it is interesting. If you delete it, I will not revert. Emmanuelm (talk) 17:08, 11 January 2008 (UTC)

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Merger proposal

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According to the definition of Ur-organism found in its article, there seems to be no need for both articles on "ur-organism" and "LUCA". I am not familiar with the ur-organism concept, but it also seems possible to me that it actually refers to the first instance of life or even the First Common Ancestor (as discussed above), and that the definition listed at Ur-organism is incorrect. Does anyone know anything more about this? Should the two be merged and disambiguation be set up or should the definition of ur-organism simply be rewritten accurately? -Thibbs (talk) 21:58, 3 May 2008 (UTC)

In Google scholar, a search for "ur-organism" returned 8 hits, only one article using this term in its title. A search for "last universal common ancestor" return 53,000 hits. As per WP:Fringe, I vote we kill the Ur-organism article and redirect it to this one. Emmanuelm (talk) 20:18, 4 May 2008 (UTC)

Sounds good to me unless as I suggested earlier ur-organism actually means something different than it purports to in the ur-organism article. I'll try to do a little follow up on this. -Thibbs (talk) 23:36, 4 May 2008 (UTC)

OK, well this is proving to be more of a challenge than I'd thought. There seems to be much confusion of language online about what the term means. Harold J. Morowitz' book, Beginnings of Cellular Life: Metabolism Recapitulates Biogenesis (1993, Yale University Press) suggests that

"We envision the Ur-cells as being very simple, whereas the universal ancestor must—by comparison to these—have been quite complex. Thus, the gap between the approach from above and the approach from below must be filled by an evolutionary path from the ur-organism to the universal ancestor. The problem is not simply the origin of life, it is the physical formation of the the Ur-organism and a subsequent evolutionary epoch giving rise to the universal ancestor."

Later in the chapter he refers to the ur-organism as "a protobiotic form." This source, then, clearly supports the idea that "ur-organism" is a term for the First Universal Ancestor (not to be confused with the First Living Organism) rather than the Last Universal Ancestor. There are a few corroboratory sources from the social sciences or religious scholarship which I would hesitate to rely upon (eg. Rist's paper and Unger's article which was referenced in Google Scholar...). There are also an irritating number of folks online who employ the term "ur organism" to mean "your organism" as in "u take ur organism and put it undr teh microscope." The wiki article, Ur-organism, references Darwin as the originator of the term and I have run text searches on online versions of Origin of Species to no avail. I have not yet run tests on Descent of Man or his other works. I notice that Oparin has also been referenced but I have not yet examined his use of the term (if indeed he has used it at all). Before doing difficult-to-reverse changes to wiki, though, it seems to me that we need more authority than the unreferenced definition found in the ur-organism article. If anyone can find any information on the use of this term it would be very helpful. -Thibbs (talk) 00:37, 5 May 2008 (UTC)

Another option, incidentally, is to simply merge "ur-organism" with "abiogenesis" somehow. Prior to any merge, though, we need to get consensus on the definition of the term "ur-organism." -Thibbs (talk) 00:41, 5 May 2008 (UTC)

Another search at Google Books found two mentions in the context of evolution. No Darwin, no Oparin. Fringe comes to mind once more.

BTW, I'll bet (less than a dollar) that this weird word comes from Ur, the birth city of Abraham, the founder of all monotheistic religions. Emmanuelm (talk) 03:23, 5 May 2008 (UTC)

I lost my cheap bet with myself. From Audi Quattro the "Ur-" prefix is a German augmentative used, in this case, to mean "original" . Emmanuelm (talk) 03:30, 5 May 2008 (UTC)

Wow, Thibbs, the LUCA concept is a theoretical construct based on analogy (genetic and others) between currently living organisms. The adjective "last" is used to mean "most recent". It refers to the fact that this bug was most certainly not the first living organism but was itself the result of a long evolution. This evolution is, unfortunately, locked in a blackbox that may never be cracked by science. This is briefly explained in the article. You may expand it if you have time. Emmanuelm (talk) 13:53, 6 May 2008 (UTC)

Emmanuelm, you are incorrect that the term LUCA requires that "this bug was most certainly not the first living organism but was itself the result of a long evolution." It is possible that LUCA could be the same as the first instance of life in the universe, although this is more unlikely than your guess. I am very cognizant of the fact that this article is about the "last" (meaning "most recent") ancestor common to all life and I don't believe I've made any claims to the contrary. You must recognize, however, that there is a small chance that the last common ancestor to all current life is also the last common ancestor to all life that ever lived. I don't propose here to change the article to focus on this, but I certainly object to the assertion that this LUCA "bug" was most certainly not the first living organism when in fact it may well have been. (Incidentally I would also caution against using the term "bug" to describe the LUCA as bugs are, in fact, orders of magnitude more complex than the LUCA organism would statistically certainly have been). Perhaps to clarify I should mention that the FUA discussed above would also be a theoretical concept based on genetic analogy between organisms, however the scope of its analogical pool would include organisms (non-extant) that are not included in the line of the LUCA's ancestry. I will add a quick example to better explain this tricky concept above.

I think we have drifted away from the main topic of this thread, however. My question, to reiterate, was: Does the term "ur-organism" mean "LUCA," "First Universal Ancestor," or "First Living Organism?"

PS - Thanks for your contributions so far, Emmanuelm. I am glad at least someone else is aware of this corner of wiki. If there is anyone else out there who knows anything about the issue at hand or can help in any way please feel free to chime in. -Thibbs (talk) 15:52, 6 May 2008 (UTC)

Once this merge dispute is resolved, can someone fix cenancestor to point to the best article describing it? Thanks. StevePrutz (talk) 04:37, 22 May 2008 (UTC)

After a quick Google, I conclude that cenancestor is a synonym of LUCA. I changed the redirection of cenancestor to reflect this. I still think that ur-organism is different and should probably be redirected to origin of life. Emmanuelm (talk) 21:22, 23 May 2008 (UTC)

I agree with Emmanuelm that ur-organism is most likely different from LUCA. I had written to the creator of the article on "ur-organism" and he has not responded. I will go ahead and remove the redirect tags for ur-organism->LUCA and rewrite the lead for ur-organism so that it can no longer be confused with the LUCA. -Thibbs (talk) 21:36, 24 May 2008 (UTC)

Thibbs, I like what you wrote in Ur-organism; I clarified it further. I think that article can now be laid to sleep.

Now, to come back to a much more interesting argument, you wrote above I certainly object to the assertion that this LUCA "bug" was most certainly not the first living organism when in fact it may well have been. Please have a look at some very cool animated videos of DNA duplication, transcription and RNA translation linked here. Then tell me again: do you honestly believe that this extraordinarily complex and precise machinery which, by the way, was fully functional in the LUA, could be the first functioning cell? When the chance of an event occurring is vanishingly low, one can say it "most certainly" did not happen this way.

I let good sense dictate my writing, not absurd rhetoric. Good sense tells me that such a complex process is the result of a very long evolution. The fact that we have no trace of this evolution is unfortunate but does not make it non-existent. Emmanuelm (talk) 15:05, 29 May 2008 (UTC)

Thank you. I agree that "ur-organism" is more or less finished now and I think your additions were valuable there. A few unsourced claims remain such as the Darwin connection, but I think that on the whole it is much less confusing now.

As far as my earlier suggestion that there was a small chance that the hypothetical LUA may have been the first living organism, I should start by clarifying that I don't consider this scenario likely. I tried somewhat unsuccessfully to make this clear in the sentences just prior to the one you've quoted. Regarless of my doubts as to its likelihood, however, it is important to remember that strict adherence to the definition of LUA should not be confused with "absurd rhetoric" considering that even an organism which has left no trace may still be described accurately. With nothing but a definition and the analogies that can be drawn from extant organisms, it strikes me as rather foolhardy to make statistical certifications of the processes by which the LUA's hereditary information was replicated when the scientific community is simultanously statistically certain that most extant organisms remain undiscovered. All it would take would be the discovery of an RNA-based lifeform to chip away at the currently "known" attributes of this conceptual LUA organism. I believe such a discovery is unlikely but hardly "vanishingly low"... In general I believe that when speaking of the LUA we must guard ourselves against fixing on any of these "known" attributes as "most certainly" true even if we strongly believe them to be so based on current evidence.

Please also note that I am not proposing to change the text of the article to reflect this hypothetical scenario involving the discovery of an RNA-based lifeform. I believe that such a suggestion might unnecessarily muddy the waters. Yet I maintain that it was quite pertinent to bring up the possibility that the LUA and first living organism could be one and the same insofar as this suggestion arose during a dialogue about hypothetical organisms restricted to only the talk page.

PS - That was a pretty cool animated video. It's a pity about the video quality, but I certainly agree with your argument that such complexity could not have come from a single evolutionary step short of some sort of non-evolutionary act such as interstellar seeding, etc. I am actually quite a sucker for animated demonstrations of biological concepts, so my thanks to you. -Thibbs (talk) 22:22, 29 May 2008 (UTC)

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New Scientist Article 21. JAN 2009

This looks interesting. Info from this source might be good to extend the article with.

"Why Darwin was wrong about the tree of life". New Scientist (2692): 34–39. 21 January 2009.

--InsufficientData (talk) 21:47, 25 January 2009 (UTC)

That was before the big statistical test in 2010. We have new evidence in favor of LUCA since that article was written. The Mysterious El Willstro (talk) 18:29, 16 May 2013 (UTC)

Problem at Organism

The article at Organism contains material about the last universal ancestor that has been removed from this article, namely whether there is significant scientific debate about the existence of an LUA. See Organism#Was there a universal ancestor?. Should this article mention that there is a minority opinion held by the religiously motivated "intelligent design" advocates? --Bejnar (talk) 22:59, 11 December 2013 (UTC)

The point about lateral gene transfer making it difficult to pinpoint the LUCA is a good one and definitely relevant to this article. Opposition from the the ID crown would only be relevant to the degree there are relevant good sources for it. Petter Bøckman (talk) 08:07, 16 December 2013 (UTC)

It would be extremely difficult to "pinpoint" LUCA in the sense of reconstructing its exact genome. Horizontal gene transfer does make that task even more difficult. Even with horizontal gene transfer, though, the odds that LUCA existed are astronomically in favor. 10³⁴⁸⁹. Horizontal gene transfer does not negate the existence of a single ancestral cell at some point; it only pushes back the date when that cell would have lived even longer ago. This is what Theobald (2010) clarified, truly a landmark paper.

If you're talking about LUCA being difficult to pinpoint, that is true. If you're talking about the existence of LUCA, however, the math definitely vouches for its existence. The Mysterious El Willstro (talk) 04:44, 21 December 2013 (UTC)

No, I was not discussing the existence of LUCA, I was as you suggested refering to the time of existence (though obviously not clearly enough). I suggest wording an entry something like this: "Transfer of genetic material between cells (horizontal transfer) makes it very difficult to pinpoint both the exact genetic the LUCA, and pushes the time of its existence back.", or something to that effect. Petter Bøckman (talk) 14:10, 27 December 2013 (UTC)

Ah, I see your point there. The Mysterious El Willstro (talk) 04:36, 27 March 2014 (UTC)

Species or single cell?

Are we talking about a species here, or about a single, individual cell? -- 77.7.152.59 (talk) 02:03, 24 November 2010 (UTC)

We are talking about 1 individual globule (early cell) whose lineage survived beyond the very earliest evolutionary period. There were any number of globules of the molecules now known as biological polymers that came together during the Primordial Soup Event, but only 1 whose lineage survived, and the evidence for this lies in the biosphere's common chemical features some of which are already listed in the Article. Does that make sense? The Mysterious El Willstro (talk) 07:01, 7 February 2011 (UTC)

I suppose we can be fairly certain this was a single cell organism. The single cell status is referred to in the last few bullet points, but not stated explicitly. It probably also had a cell wall as this is primitive to both Archeans and Eubacteria. Why aren't these rather basic traits mentioned in the article? I am sure the reader not well versed in cell biology would like some "what was this critter like" type of gross morphology information, not just the technicalities of the internal workings. Petter Bøckman (talk) 22:32, 28 December 2011 (UTC)

Petter Bøckman, in principle I agree. The issue is that many finer details of what this critter was like are actually not conclusively known. The Mysterious El Willstro (talk) 03:42, 25 March 2012 (UTC)

Actually, the finer details of this critter are surprisingly well known (details of metabolism etc.). What I’m after are the larger traits which it seems the authors of this article have not bothered with as they are self-evident to anyone with a smattering of biology (single cell, cell wall, generally “bacteria-like”). I was thinking a sentence like:

"Considering what we know of the offspring groups (see phylogenetic bracketing), the LUCA was a small, single-cell organism. It would have had a cell wall and a ring-shaped coil of DNA (or possibly RNA) floating freely within the cell, like modern bacteria. It would likely not have stood out against a collection of modern generalized small size bacteria." Petter Bøckman (talk) 13:13, 30 April 2012 (UTC)

References

By finer details, I mean we don't know LUCA's exact genome and proteome (and unfortunately, it's quite possible that we never will). We don't know anything else at that level of detail, for that matter.

More to the point, I support your sentence to be added, minus the "(or possibly RNA)" part. Bearing in mind that this is the Last Universal Common Ancestor, not the abiogenic Ur-organism, it would have been post-RNA-world, although a very early DNA-based organism. (I talked about this with my Micro. Professor before I graduated this past May.) The Mysterious El Willstro (talk) 18:15, 17 July 2012 (UTC)

Just to dig this up again, someone explain for me, why it couldn't have been a colony of sister cells, of which some branched off into this and some into that. Or would that just mean LUCA is the first of that cell lineage? Couldn't some very similar but non-identical cells have started the various lines? Why not? I have the idea of a certain amount of little cells floating around at the time, quite advanced compared to early lipid-bags of replicating proteins, but with some genetic variation. So why would only one of them be the ancestor? Don't most animals evolve from populations of ancestor animals, rather than just the one? With a genetic range before speciation chops the range off. I'm not arguing, I want to know, but this isn't obvious from what I can read here. 94.197.121.12 (talk) 22:31, 27 May 2015 (UTC)

Best name

There appear to be four possible names for this article, and it does not look as though the current one is the most usual. I did a google search (with "-Wikipedia") on the following terms (without the abbreviations), obtaining the following results:

• Last Universal Ancestor, LUA: 10,300
• Last Universal Common Ancestor, LUCA: 112,000
• Cenancestor: 5,000
• Progenote: 10,300

Recent announcements in the media (such as the New York Times article cited in the item above) have all used "LUCA", which may not prove anything, but is suggestive. LUCA also reads as a clear descriptive term, which would be an advantage. Given LUCA's runaway top score, and for these other reasons, I propose that we rename the article, preserving redirects from the other three terms. Chiswick Chap (talk) 18:07, 13 September 2016 (UTC)

2. Google Trends currently shows Last Universal Ancestor being used more in searches than Last Universal Common Ancestor: https://www.google.com/trends/explore?date=all&q=Last%20Universal%20Ancestor,Last%20Universal%20Common%20Ancestor,Cenancestor,Progenote

The 2 terms have traded places since 2004. I am not certain counting google searches is a scientific approach. I prefer Last Universal Common Ancestor as a more descriptive name.CuriousMind01 (talk) 23:57, 13 September 2016 (UTC)

Thank you. One consideration we have not yet analysed is in titles of scientific papers, using Google Scholar, a quite different tool:

• Last Universal Ancestor, LUA: 10,300 (Scholar: 491)
• Last Universal Common Ancestor, LUCA: 112,000 (Scholar: 4,130)
• Cenancestor: 5,000 (Scholar: 574)
• Progenote: 10,300 (Scholar: 1260)

This does not indicate whether LUA may once have been a major term or not, but it is certainly far behind LUCA, and is apparently last behind Progenote and Cenancestor also. Chiswick Chap (talk) 05:57, 14 September 2016 (UTC)

Orphaned references in Last universal common ancestor

I check pages listed in Category:Pages with incorrect ref formatting to try to fix reference errors. One of the things I do is look for content for orphaned references in wikilinked articles. I have found content for some of Last universal common ancestor's orphans, the problem is that I found more than one version. I can't determine which (if any) is correct for this article, so I am asking for a sentient editor to look it over and copy the correct ref content into this article.

Reference named "IND-20171002":

• From Earliest known life forms: Johnston, Ian (2 October 2017). "Life first emerged in 'warm little ponds' almost as old as the Earth itself - Charles Darwin's famous idea backed by new scientific study". The Independent. Retrieved 2 October 2017.
• From Abiogenesis: Johnston, Ian (2 October 2017). "Life first emerged in 'warm little ponds' almost as old as the Earth itself - Charles Darwin's famous idea backed by new scientific study". The Independent. Archived from the original on 3 October 2017. Retrieved 2 October 2017. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

I apologize if any of the above are effectively identical; I am just a simple computer program, so I can't determine whether minor differences are significant or not. AnomieBOT⚡ 14:38, 10 October 2018 (UTC)

Location of the root

I want to point out that the base of the tree has nothing to do with the origin of life. Any conclusion that comes from LUCA analysis can not directly touch the orgien of life. In the same way, I would take the results of Willian Martin's group very carefully, if you read the articles, the conclusions are not really well supported. Avazquez-salazar (talk) 19:03, 24 October 2018 (UTC)

To-do

There are many inaccuracies with this article. For example, it says "Only 20 amino acids were used, only in L-isomers" -- but it's pretty well established that LUCA had selenoproteins. Much of the "Features" section lacks reliable sources (16-19 are all from more than a decade ago), and it would be reasonable to rewrite the paragraph (The genetic code was expressed into proteins ... chemical pathways) entirely. I also suggest combining Martin (2016)'s findings with the "Features" section. Allopathie (talk) 02:53, 31 January 2019 (UTC)

Why does progenote redirect to this article?

Granted, the first sentence says that LUCA is sometimes called "progenote", but also says that it's a misnomer, so progenote is a different thing and should have its own article or redirect to somewhere else IMHO (perhaps Three-domain system or Darwinian_threshold#Before_the_Darwinian_Threshold). Apokrif (talk) 16:25, 6 August 2019 (UTC)

Age from Bristol paper - contradicted by new Moon data?

In the Uni. of Bristol paper cited in the introduction, they themselves put a hard limit on the age of the LUCA at the date of the Moon's formation (in line with the giant impact hypothesis). It certainly defies credulity that cellular life could survive a collision between planets, given that the Earth's crust would likely liquify and the atmosphere would be briefly composed of gaseous rock.

Recent work on the age of the Moon constrains its formation between 4.40 and 4.45 Ga "A long-lived magma ocean on a young Moon". Science Advances.. This post-dates the 4,519–4,477 Ma range for the LUCA given in the bristol paper by 10's of millions of years at least. It appears that one of these papers (or the GIH) must therefore be incorrect.

Is it worth noting this in the article? As I think this casts significant doubt on the calibration used in the paper.

00A86B (talk) 17:12, 18 August 2021 (UTC)

Well, it's one view only, but more importantly here we editors are not allowed to reason and make inferences under the WP:OR rules. In truth, the difference between the "maybe 3.5 billion years ago" estimates differ so largely from the 4.x/moon age estimates that a few tens of millions is small beer. I think we'd best just ignore it. Obviously if someone writes a review article critiquing the Bristolians on this point then we can mention it. All the best, Chiswick Chap (talk) 19:23, 18 August 2021 (UTC)

That's very fair, though I wonder if it is worth mentioning in a more general sense that the date of lunar formation is considered a lower bound (for both LUCA and abiogensis)? It's easy enough to find 2-3 papers on LUCA that all agree that ancestors of modern life cannot predate this. 00A86B (talk) 12:32, 19 August 2021 (UTC)

You can say that, citing it to a suitable source. Chiswick Chap (talk) 12:48, 19 August 2021 (UTC)

Is LUCA plural or singular

I'm not a scientist, just took interest to this subject.

This article describes LUCA as "population" of organisms. Shouldn't it be just an (one) organism? Especially as I saw another Wikipedia write-up alluding to an individual unicellular organism? Vusi Dlamini (talk) 03:40, 20 September 2021 (UTC)

Grammatically, it's singular. However, it's not the case that there was exactly one cell which lived for millions of years and then suddenly gave rise to all life as we know it. There was always a population. If you follow the logic and trace the ancestry back and back, you arrive at a set of genes that all life today shares; that set must have been possessed by an individual, way back when. That doesn't exclude the notion that a lot of similar individuals were all around at that time. Hope this helps a bit. Chiswick Chap (talk) 08:32, 20 September 2021 (UTC)

both of you are wrong. common ancestry DOES entail one individual ancestor. but saying that there was one last common ancestor does not mean that this last common ancestor did not leave in a population. me and some guy in bulgaria share a most recent common ancestor in one dude and girl. i don't know who this couple was, but it's one couple. that doesn't exclude that this couple lived in a population of other people.

at the same time, there is a broader interpretation you could have of universal common ancestry. some scientists think there was a single discrete organism that was the universal common ancestor of all life. but some scientists are compelled by the idea of a 'communal common ancestor', first proposed by carl woese to my knowledge. it's a bit complicated to explain here, but ill leave yallw ith thatHaddarr (talk) 05:28, 26 December 2021 (UTC)

Your reply demonstrates that you did not understand what I said above, or, since your account is in fact equivalent to mine, that you did not read it. Chiswick Chap (talk) 10:31, 26 December 2021 (UTC)

it is not equivalent. the communal understanding of LUCA is not equivalent to a population of discrete individuals. Haddarr (talk) 23:09, 26 December 2021 (UTC)

The article has LUCA confused with the early microbial community (which was a community; but not a proper "population" since discrete species and taxa didn't readily exist yet). LUCA was a single bacterial cell whose descendants survived.

It's a little bit like the case of the Mitochondrial Eve. There were plenty of other women alive in her time, but their lineages died out.

The LUCA is basically a much broader version of Mitochondrial Eve, this time concerning all life rather than just humans in particular. Hope that helps. Master's Degree in Biology, by the way. The Mysterious El Willstro (talk) 08:05, 29 December 2021 (UTC)

Citations in the lead

There are 25 citations currently in the lead, and 23 of them (!) are not used anywhere in the article body. This runs contrary to the "no new materials in the lead", as the lead is meant purely as a summary of the rest of the article. If those 25 sources are important, they should be in the body, either as well (if the lead text is debated) or removed from the lead altogether. Currently, it's just a mess. Chiswick Chap (talk) 13:27, 9 May 2022 (UTC)

Well since that clearly needs fixing, I've created a new 'Age' section and moved the materials out there, but for some 'Historical' stuff which has gone to that section. Chiswick Chap (talk)

Recent Reseach 2021

This could be of interest:

https://www.inverse.com/science/hydrogen-powered-life?utm_source=pocket-newtab-global-en-GB (How did life arise? New study offers fundamental evidence for a disputed theory)

points to:

https://www.frontiersin.org/articles/10.3389/fmicb.2021.793664/full#B62 (Energy at Origins: Favorable Thermodynamics of Biosynthetic Reactions in the Last Universal Common Ancestor (LUCA))

79.74.128.144 (talk) 01:21, 26 December 2021 (UTC)

It shows that basic components can arise spontaneously; what it doesn't show is how those components can be combined, which does require an input of energy. That leads to all the questions about how you manage with or without an ATPase, a major reason why the energy available via the "free" pH gradient in a hydrothermal vent is of interest. Any alternative habitat scenario must of course answer the same question. Chiswick Chap (talk) 08:06, 11 October 2022 (UTC)