Talk:Last Common Ancestor

message: As for the cartoon, it was reinstated.  It appropriately makes the point defined later in the text, ie., "...the LCA is the seminal individual that first coded the mutation..." That would be mom or dad, no way around it.  I cannot believe someone would have a problem with that illustration in Wikipedia!  And if he did this discussion page is the place to make the case, not with some hit and run on the article. Tom Schmal 02:48, 15 August 2007 (UTC)
replies: text: How is that possible without us being clones of the LCA? 207.189.230.42 (talk) 09:05, 24 July 2008 (UTC)

text: First you would have to define what crucial characteristic suddenly makes an offspring the first member of a new species, and not a member of its parent(s) species.  Is that even tenable? 207.189.230.42 (talk) 09:05, 24 July 2008 (UTC)
thread_title: Previous discussion

message: Here are some web pages I am looking at now. Unfortunately, some of these only show abstract. Fred Hsu 01:27, 7 November 2007 (UTC)
thread_title:  Possible references for LCA 

message: I am removing the following content.  For sake of fairness, I move them here.  If anyone can find real references for these, feel free to move them back to the article, with proper inline citations. Fred Hsu 04:11, 7 November 2007 (UTC)
thread_title:  Removed content 

message: I have promised myself not to post any more useless replies here. Following are things to consider for whoever ends up resolving this dispute. Of course, please do read the entirety of this talk page as well. Fred Hsu (talk) 01:35, 10 December 2007 (UTC)
thread_title:  Things to consider - for whoever tries to resolve this dispute 

message: Ok, Fred here is my summary
In describing the individual (or founding population) at the bifurcation of two taxonomic groups (eg, of chimps and humans) the literature uses two terms - either the most recent common ancestor or the last common ancestor.  In my view, the latter more often used as a proper noun, eg, the LCA.  So if (as you say) Wikipedia has room for only one of these terms then the more proper name, LCA, should be the survivor.  Defining “most recent common ancestor” is too trivial.  Like “most recent fashion,” it does not really require a Wikipedia entry.  
The main value in retaining it as an article is the work done in lineage models by Chang and others identifying the Most Recent Common Ancestor of All Mankind.  We do not know exactly when the MRCAAM lived, somewhere 2,000 to 5,000 years ago.  It would have been handier had Chang dropped the word “Common” from his discovery’s name, but he didn’t.  Thus the definition for most recent common ancestor of all living individuals in a species has been taken, and can’t be used to describe someone else.
Which brings us to: Is LCA the proper name for the founder of a species?  As I noted in the links above, LCA is commonly used in literature to identify the founder of a taxonomic group.  “LCA of primates,” "LCA of all humans,"  “LCA of metazoans,” even LCA of mtDNA.  Above the species level, “MRCA of Primates” is probably equivalent to “LCA of primates.” Below the species level however, MRCA does not work. For example, Chang's MRCA of All Mankind means something else entirely and can’t be used as the name of the founder of the species. 
I don’t know if LCA is the only term to describe the founder of a species.  “Concestor” might work.  “MRCA of all mankind living and dead might work.”  But right now LCA as founder of a species is being used in the literature and is the proper subject for a Wikipedia article.  
Fred, I am putting out a request for comment.  I saw that you had found the links to LCA and replaced them with links to your MRCA article.  No wonder you are the only one discussing here!  To you who do care to read the original article, the one in question, you may find a copy of it here . 
  Tom Schmal (talk) 19:28, 14 December 2007 (UTC)
thread_title: Things to consider (from Tom)

message: For example, computer simulations suggest that every person living today could share a common ancestor who lived as few as 2,000 to 3,000 years ago. This person (name lost to history) has been entitled the Most Recent Common Ancestor (MRCA) of All Mankind. But there have not been any speciation events in Homo sapiens during the past 3,000 years, so this person cannot have been the LCA with any other species.
(Emphasis mine)
This seems unlikely: Asia and Europe were cut off from one another with what was likely quite minimal gene flow by 1000 BC and long before. Sub-Saharan Africa was also cut off, not to mention the more complete isolation Mesoamerica, Australia, &c. To say that we possess a common ancestor 2000-3000 years ago is to say that this founding population must have dispersed and either displaced or mixed with all other human cultures on the earth, since 2000-3000 years ago!! This clearly does not allow for reproductively isolated populations since then. Edit: I noticed the conflict between LCA and MRCA, but this computer simulation still does not seem like evidence to me, i.e. it seems more like what might have been (speculative) than what actually happened (factual). I have also noticed the problem of intermarrying in very recent times, but does this apply to very isolated, rarefied populations like the Negrito, who have effectively resisted foreign influence until the 20th century?
I would have less of a problem with this if it were highlighted that this scenario is completely artificial and oversimplified. --♦♦♦Vlmastra♦♦♦ (talk) 03:26, 8 January 2008 (UTC)
replies: text: Yes, I think the MRCA article has more complete and accurate descriptions of related concepts. And it contains proper inline citations for all paragraphs.  This is, mhm, because I took the pain to rewrite in a while back ;) Joking aside, you may want to check out Dawkins's The Ancestor's Tale for more accessible information. Fred Hsu (talk) 04:47, 8 January 2008 (UTC)
replies: text: Fred, please.  This place is for outside comments.  Tom Schmal (talk) 14:59, 12 January 2008 (UTC)
replies: text: Tom, it's not. This is a new section. I moved your comment down one line and properly indented it. Please follow the wikipedia styles when you write, both on article pages and on talk pages. Fred Hsu (talk) 13:34, 13 January 2008 (UTC)
thread_title: Last couple sentences

message: As explained in previous talk sections, MRCA=LCA generally. And the MRCA article has more complete, more accurate description of concepts with properly written paragraphs and citations. I will now examine both articles and make sure we don't lose anything important and correct in LCA during this transition. For reference, the current version of LCA at the time of this transition is this version. Fred Hsu (talk) 05:57, 6 June 2009 (UTC)
thread_title:  Merging LCA into MRCA