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Due to an inquiry in Last Common Ancestor I took a shot clearing up the confusion, maybe this will help.
An LCA is in fact the individual (or founding group) at the bifurcation point between two species. For us, this individual, which lived between two million and 40,000 bce, and no others contributed ALL of the genes that make up humanity. If we could pin the date down more closely we could probably call it "The MRCA between modern man and XXX" but we don't know the XXX.
Now fast forward to 2007. You and I and every person on earth could trace our ancestries back to around 2,000 years ago and find a common grandparent, aka The MRCA of All Mankind. Unlike the LCA, the genetic contribution of this ancestor to any one person is extremely small. This is because some ten million of his contemporaries ultimately get into the action.
Obviously the MRCA of All Mankind cannot be both of these individuals. Chang, et al, call the individual of 2,000 years ago the MRCA of All Mankind. So we call the other guy, the individual that began the species, the LCA (of all mankind).
Tom Schmal 06:19, 6 November 2007 (UTC)
This section states "The MRCA of humans alive today necessarily lived more recently than either." This is incorrect. If we imagine that there are four living humans, two males and two females, with matrilineal ancestor 3 generations back, with the males having the same father, then the "most recent common patrilineal ancestor of all living male humans" is more recent than the MRCA of all humans. Even if we use a definition of y chromosome Adam that includes the patrilineal ancestor of living females, this is still only exactly as recently, not more recently.
I'd suggest changing this to "The MRCA of humans alive today likely lived much more recently than either. By definition, the MT-MRCA is a common ancestor, but not likely the most recent. The Y-MRCA is by definition only the common ancestor of all males, but still likely to be much deeper in the past than the unrestricted MRCA, who may be an ancestor on any line."
But I don't have a citation for this. Can someone verify that the cite given for the original actually says this? I think someone may have simplified it, but using "necessarily" could be confusing. Kevinpet 06:12, 21 August 2007 (UTC)
from VfD:
Keep. Nunh-huh's fix makes the page work for me. I am replacing the VfD with a "stub" to save everybody's time. If you think otherwise, then please replace the VfD notice on the Most recent common ancestor page and post your objections above. Thanks. --- Rednblu 20:22, 2 Oct 2004 (UTC)
end moved discussion
I believe the confusion about this term is to do with how a single individual can pass on his or her DNA to all living individuals. The Most Recent Common Ancestor is a misnomer for the Most Recent Prolific Ancestor. Shared DNA merely means a single ancestral tree among a forest of ancestral trees has passed DNA on to all living individuals via prolific production of progeny who spread out through all the DNA trees of all living individuals. It is not indicative of a single source but merely a indicator of a single common point of some source DNA among many sources of DNA. IF you were to talk about multiple points of infection and view this shared DNA as if it were a virus you would realize it is just one virus among many but that it has infected everyone through time. It can then be viewed as an indicator of a very mobile population group who shared a common ancestral root and who seeded their DNA into many DNA trees throughout all know population groups. So the MRCA aka MRPA becomes an indicator of the most recent spread of a single source of DNA among all groups.
—The preceding unsigned comment was added by 210.209.65.40 ( talk) 09:25, 5 April 2007 (UTC).
I believe that the MRCA is purely a mathematical model which accounts for mutation rates, migration, etc, but has nothing whatever to do with individuals taking genealogical DNA tests. If I'm correct then the second paragraph of this article should be revised.
One alternative might be the insertion of a new paragraph to distinguish between meanings. Here's a stab at it:
The term is used in two ways. In ordinary usage the most recent common ancestor refers to:
- An individual identified as the most recent ancestor of two persons -- by DNA testing of two males or two females, or by traditional genealogy.
In scholarly usage, however, it has another meaning:.
- An individual who lived at a time which has been estimated by a mathematical model accounting for the rate of mutation (and sometimes also the rates of migration, inbreeding, etc.) and who is the most recent ancestor of all males, all females, or all living persons.
Any comments, objections, etc.? AnonUser 14:49, 14 October 2005 (UTC)
I agree with the focus as is. The article is confusing, however, because it uses multiple definitions of MRCA. I propose that the article clearly distinguish among them up front. AnonUser 19:24, 14 October 2005 (UTC)
Ah so -- you are correct. Perhaps its confusing because the examples are so dissimilar, without language tieing them together. If its confusing to me, its probably confusing to other readers too. Maybe a little tweaking would help. AnonUser 02:57, 15 October 2005 (UTC)
Long discussion here. My issue is that on one hand we are saying the MRCA may have lived in the common era, on the other hand we are saying MRCA lived in paleolithic, defined in that article as 2.5 MYA to 10 KYA. This is not helpful at all, we need a tighter bound. Since we know from the y-chromosomal Adam article that he lived just 60 KYA, can we at least deduce that MRCA was more recent than that? This would place MRCA between 60 KYA and 1000 CE. If no counter-comments I will update. Skates61 ( talk) 23:29, 27 June 2008 (UTC)
Ok, rwr8189 was correct in reverting my blank out of this section- the cited articles are in Nature and have subsequently been cited by others, and after reading them they certainly make a case worthy of discussion. However, I feel there two corrections should be considered: 1. in the '04 article they use the admittedly naive system in which any two humans can randomly breed in any given generation (this yields the 1000 CE date). This simplification should be explicitly stated as a model, or the very-recent daate should be dropped in lieu of the same group's more advanced and recent estimate (the 2005 nature paper). 2. Make the point that for a given non-isolated population, the MRCA is surprisingly recent, but also that the existence of even a single isolated population or insufficiently mixed population implies a much earlier MRCA (though still not the tens of thousands of years I had expected.) coments? Jodine Sparks 20:20, 3 July 2007 (UTC)
This section is based on a single study amongst a fairly large field of research, and the results of said study are patently false. Until someone can rewrite it with actual 'time estimates' that correspond to a older MRCA than 1000AD (which is obvious), I just going to comment it out. I hope this is not too presumptuous, but this section as it stands is only presenting known misinformation.
Jodine Sparks
16:45, 29 January 2007 (UTC)
To: EamonnPKeane. Kindly state all your assumptions, including:
The "historical times" estimate is patently ridiculous, imho; it seems they used some sort of diffusion to model human migration. The statement
betrays the preceding estimate: We defined the MRCA as that of all humans alive today, so what do you mean "if one attempts to take into account tribes in Central Africa"? Unless you want to argue they are not human, you'll have no choice but to take them into account. I can easily believe the MRCA of Europeans (or even continental Eurasians) lived in the Common Era. It is inconceivable that the MRCA of all humans lived after 3000 BC: A single isolated tribe (Pygmies, Aboriginals, Indonesian bushmen, take your pick) pushes the MRCA back to the Paleolithic. I can easily imagine, even, that the MRCA of 99% of humans alive today lived in historical times, but it takes just a single surviving individual from an isolated lineage to render that calculation obsolete. dab (ᛏ) 09:56, 3 January 2006 (UTC)
I think that the suggestion of a human MRCA having lived from between 3000BC to 1000AD(!) is absolutely ridiculous. What kind of pseudo-science must this be? Think about it, if it were true, there would for example be no single 100% pure-blooded Native American alive today (since the Native Americans had reached and spread throughout the American continents well before 3000BC, a possible exception to this being the Eskimos) which, be they few, I think there are.
I agree that this is ludicrous. Are we talking about all humans or aren't we? Ancestors of Aborigines are believed to have arrived in Australia between 40k and 50k years ago: http://en.wikipedia.org/wiki/Indigenous_Australians I have a hard time believing that I, a white man, have a common ancestor with a black aborigine as recently as 4000 years ago. Who wrote this crap? Additionally, that time estimate 3000BC to 1000AD suspiciously encompasses when the Christian or Hebrew "creation" would have taken place. Zmbe 06:02, 11 March 2006 (UTC)
The whole concept of a purely mathematical MRCA is both unscientific and useless. It assumes the nonsensical notion that one's ancestors double with each generation backward, so that, for example, 20 generations ago I had a million (2^20) ancestors, or almost that many. But the human genome contains no more than 25,000 genes! In other words, no matter how many generations back I go, I cannot have any more than 25,000 genuine ancestors--i.e., ancestors who have actually contributed to my genome. All the other thousands or millions are ancestors on paper only, and have no scientific or practical significance.
Let's now even consider those 25,000 distant ancestors. Each contributed as little as a single gene to my genome. Big deal! Such an ancestor still has no practical significance to those living today, unless perchance that ancestor contributed a crucial improvement to humanity that we now all share. But I know of no such great improvement in the human genome within the last 70,000 years.
The bottom line here is that, beyond 20 generations, the ONLY ancestors that are of practical significance to humans living today are the two ancestors who contributed a SIGNIFICANT quantity of genetic material: the Y-chromosome ancestor and the mitochondrial DNA ancestor. Thus, it is for good reason that those interested in distant genealogy (beyond 20 generations) focus on the strict patrilineal and matrilineal lines.
"The whole concept of a purely mathematical MRCA is both unscientific and useless. It assumes the nonsensical notion that one's ancestors double with each generation backward, so that, for example, 20 generations ago I had a million (2^20) ancestors, or almost that many. But the human genome contains no more than 25,000 genes! In other words, no matter how many generations back I go, I cannot have any more than 25,000 genuine ancestors--i.e., ancestors who have actually contributed to my genome. All the other thousands or millions are ancestors on paper only, and have no scientific or practical significance."
Good point, except that on top of what you mentioned, there is an extremely high degree of redundancy amongst those 2^20 ancestors. In other words, not only do some ancestors contribute zero genes to you (as you pointed out), but also, a given ancestor from 20 generations back is most likely your ancestor many, many times over (so, due to the redundancy factor, the number of actual ancestors at a given number of generations back is way less than the mathematical value).
"The bottom line here is that, beyond 20 generations, the ONLY ancestors that are of practical significance to humans living today are the two ancestors who contributed a SIGNIFICANT quantity of genetic material: the Y-chromosome ancestor and the mitochondrial DNA ancestor. Thus, it is for good reason that those interested in distant genealogy (beyond 20 generations) focus on the strict patrilineal and matrilineal lines."
Here you are absolutely wrong. Mitochondrial DNA does not code for anything except mitochondria, and the y-chromosome (in males only) is far from the only chromosome that codes for traits. It is true that for a large number of generations ago, only some of an individual's ancestors of that generation contributed to his/her genetic makeup. However, it is NOT the case that these individuals are restricted to the direct maternal and paternal lines. Some of the genes that make me distinct could have come to me via my mother's father's father's mother's father's mother's mother's .... It is incorrect to say that one's genes come strictly from the direct male and direct female lines (else, why do some people clearly take after a mother's father or a father's mother?!?)
—Preceding
unsigned comment added by
151.207.242.4 (
talk)
02:18, 24 October 2007 (UTC)
I've added a section on MRCA of different species, and referenced Richard Dawkins' book, The Ancestor's Tale. I recommend it, especially to those who have contributed to the discussion above. He places a lower-bound of 13,000 years on the age of the MRCA of all humanity (with a rather sad proviso – see later). This is because it is known that the native population of Tasmania was physically separated from the rest of the world 13,000 years ago, and therefore we could not share a later ancestor with them. The only problem is that the Europeans who colonised Tasmania treated them as vermin and exterminated the whole lot by 1876. Also, FWIW, Dawkins reckons on an upper limit of 100,000 years as the age of the MRCA of all of us. -- Portnadler 17:23, 8 May 2006 (UTC)
What sort of social rank would one have to bear in their family, in order to be a descendent of either?
How far up the totem pole, would you say?
This is intended to have broad answers and based on gradients of time and population, not going into specifics about exact descendents. About how common is their descent in the English or British genepool today?
I've noticed that American Presidents don't descend from either king, but the most common recent royal ancestor shared by many of us is Edward III. How common is it for anybody in the English or British genepool, to have a Protestant royal ancestor?
There is a general cutoff, isn't there?
Is it because of fratricide in the Wars of the Roses, the Tudors' "new men", or the Union of the Crowns, or the parliamentary union under Queen Anne (I can't think of any non-royal family descent from the Hanoverians within the UK)?
I'm thinking that there is a big difference between Plantagenet and Tudor descents, that the commons in all likelihood have the former and the latter is held by the lords. (just generally speaking) Then again, Tudor descent in the Welsh must be higher in general. I am further curious about pre-Royal Tudor blood in Anglo-British people today, since the status and/or concept of Welsh royalty/nobility is rather hazy in my mind. I found the Blevins aka Ap Bleddyn family of Powys in my ancestry, but have no real idea on what to make of it--or any other Welsh "native aristocracy". I might be able to find Stewart descent somewhere, from way back when. What percentage of Hanoverian background do you think that German colonists had in America?
On the British side, I have to go as far back as Welf himself...but any recent genetic relationship with the Hanoverians or the counts of Nassau are completely obscure. How does one research those other colonial people, such as the Hessians?
UK genealogy is relatively easy when focusing on English (and French) ancestries. What would a "national person" of Jerusalem (or Antioch, for example) in Crusader times be known as?
We say "American" for those Founders, but was there such a nationality-term for the Crusaders in their own domains?
I guess the term is supposed to be Levantine/Outremer, or "Crusader" as our national heritage says "Colonist"...
IP Address 11:48, 9 May 2006 (UTC)
I have a question:
After reading the article I was happy to see how closely related we are. I would really appreciate it if someone has more detailed information on population. I just can't get past the fact that the article seems to focus on 6.5 billion people. Our ancestors came and went throughout history. From the point of our MRCA's existance to present more than 6.5 billion people have lived. The town where I lived has an approximate population of 100,000 but from the day the founder came and died to present I can't even fathom how many people have lived here. Can someone help me find the numbers I need to understand?
Approximate total of humans since time of our MRCA:???
83.219.199.121 00:38, 23 July 2006 (UTC)Leif
If anyone doesnt have a significant other because they have come to terms with the fact that we are all related let me put this into your heads. I am almost positive that somewhere out there in the universe that there is another species that are exactly like us, humonoid, but do not come from a genetic line that comes from this planet. It is an infinite universe. The distance between them (a mating partner not of our gentic line) and us is trillions of light years away.-- RCJACOBS100 23:55, 16 September 2006 (UTC)Robert Curley Jacobs
I thought this was meant to describe a graph? It clearly descibes a tree to me: "...there will eventually be an MRCA from whom it is possible to trace a path of direct descendants all the way down to every living person at the bottom..." - THAT is a tree. (by 90.242.58.236 on 06:44, February 19, 2007)
User:Robin S added the following which I just removed:
Indeed, within twenty generations, most descendants of an individual will not have inherited any of their genes from a given ancestor since there will be far more ancestors than genes. Since considerably more than twenty generations have passed since the hypothesized date of the human MRCA, it is possible that not a single human gene present today was inherited from that individual.
It is not immediately clear that in 20 generations the number of ancestors will be greater than number of genes. Please see the other paragraphs in the same session where 'tree' vs. 'graph' was discussed. Note that many ancestors are shared. Also see the chapter 'All Africa and her progenies' in River out of Eden. But perhaps you are right. We just need to find a reference which shows this to be true, taking into account the graph nature of human ancestry. Fred Hsu 17:48, 21 March 2007 (UTC)
In page 60-61 of The Ancestor's Tale, Dawkins states that he believes that the almost identical ABO blood types in humans and chimps are examples of trans-specific polymorphism. That is, a type-B human may actually be more closely related to type-B chimp than type-B human is related to type-B human, from the perspective of the genes (or alleles) responsible for the antigens.
I wanted to add this to the article to indicate that by tracing ancestry based on other genes, we may actually reach startling conclusions about our most recent common ancestor. That is, I may share a type-B MRCA with an ape, while a type-B person shares another type-B MRCA with another ape.
But after some basic research on this topic, I found that Dawkins was probably wrong on this account. First, chimps don't have blood-type B. They only have A and O. Other primates have combinations of A, B, AB and O, with the exception of macaques which has all of them. This does not necessarily indicate the B-type in human is the same as B-type in apes, for instance. It could be that there was an original type-A inherited by all apes, including human. From there other blood-types developed. And it so happened that type-B and type-O are stable variants which appeared independently in different species.
Most of the studies on blood types across apes I could read online (without paying for subscriptions) were rather old (decades-old). The two recent ones I could read did not support Dawkins' view:
Perhaps I need to get this book?
Can someone shed more light on this topic? Fred Hsu 23:33, 1 June 2007 (UTC)
Someone created a new article called Most ancient common ancestor. Notice that it is ancient, not recent. It appears to be a new name coined by the author without research backing (i.e. original research). I nominated that page for deletion. Please visit Wikipedia:Articles for deletion/Most ancient common ancestor if you wish to participate in the discussion. Again, please note that I am not nominating the Most Recent Common Ancestor article for deletion; I am nominating the newly created Most Ancient Common Ancestor. Fred Hsu 05:41, 21 July 2007 (UTC)
people for some reason seem to have a lot of difficulty coming to terms with the concept, even if great pains are taken to explain it. I just noted flawed material at Last Common Ancestor, an article that should probably be merged here. dab (𒁳) 11:16, 23 July 2007 (UTC)
Since an organism can have a copy of a gene from each parent, and these parents can share a common ancestor, does this mean that genes have ancestor and progeny graphs rather than trees? Or are two copies of a gene in a single organism not considered to be a single vertex in a gene ancestor/progeny diagram? Wikimedes ( talk) 06:54, 18 November 2007 (UTC)
Lklundin introduced two sets of changes to the article. The first set of changes is about MRCA being a set of people as opposed to a single individual. I understand the reason behind these changes. While these changes seem rational, it is not how MRCA is typically described. Since the MRCA is not a real person, but is statistically computed, traditionally we use a single person to represent this idea. If we are going to suddenly define MRCA as a set of people, then we should start to call it 'most recent common ancestors' with an 's' at the end. We should also rewrite the whole article to be consistent with this change. We should also refer to African Eves, not the African Eve, as two sisters might have had identical mtDNA and together covered all living people on Earth today.
I am going to change the first paragraph back to the way it was, ok? Fred Hsu ( talk) 00:22, 26 November 2007 (UTC)
Thank for the changes on calculation, by the way. It makes the paragraph better. Fred Hsu ( talk) 00:33, 26 November 2007 (UTC)
A section of notable coancestors, whould be really good both theoretical (roundish flatworm, Ohno's Cambrian pananimalia genomes, urcrustacean) and fossil (Wiwaxia, Hallucigenia, archaeopterix etc...)-- Squidonius ( talk) 17:26, 12 December 2007 (UTC)
Can we have something added in layman's terms? There is no real reference to what the subject matter is about and it doesn't explain clearly what the MRCA is actually for, it just jumps straight into jargon. JayKeaton ( talk) 15:36, 8 August 2008 (UTC)
There is certainly good information here, but it could be quite confusing, because at FT-DNA, they are computing time to direct paternal MRCA for two persons who have kit results. This is not the same as the MRCA on any route, which is the focus of this article. FT-DNA does not explain the distinction. Keep the link? Qualify it? Remove it? What's everyone's thoughts on this? —Preceding unsigned comment added by Skates61 ( talk • contribs) 23:36, 17 September 2008 (UTC)
From the article: "The ancestry tree is thus not strictly a tree, but a directed, mostly-acyclic graph." Am I missing something here? Barring any sort of a time-travel accident, I don't see how cycles are possible. 70.68.114.213 ( talk) 19:15, 22 March 2009 (UTC)
Hey guys - I'm a layman who is struggling to picture a last common ancestor in "family tree" terms. If the last common ancestor was part of a population of (say for the sake of argument) 10,000 humans, then does that mean that the other 9,999 don't have any descendants alive today? If not, would it be possible to produce some kind of family tree-style graphic of a mini population that has the last common ancestor labelled in an illuminatory way? Señor Service ( talk) 21:37, 5 June 2009 (UTC)
I don't get how the MRCA can be someone other than the Y-Chromosomal Adam or Mitochondrial Eve (whoever's more recent). — Preceding unsigned comment added by Deathmare ( talk • contribs) 16:24, 6 June 2011 (UTC)
Thanks for the article all. Just a question to help my understanding if I may, as I like a lot of people find this tricky to comprehend! Is it true to say that, theoretically, tracing back to the identical ancestors point for a population could give you a population that would be considered a different species? I'm thinking this situation could arise if one has to trace back a particularly long way back in time, or if the present population has come to be through convergent evolution. Kurisu rs ( talk) 13:40, 25 July 2011 (UTC)
It is clear from questions posted on the talk page that we need illustrations. If you have ideas or will be producing illustrations, please first post here so that we don't duplicate efforts. Fred Hsu ( talk) 04:23, 6 June 2009 (UTC)
But first I would like to review changes to this article since I last looked at/edited it. We can use some clean up. Also, I will probably resolve the long-standing call to merge Last Common Ancestor into this MRCA article. If you are interested in helping, please first read this talk section from LCA for where we stood by Dec 2007 on this issue. Fred Hsu ( talk) 04:23, 6 June 2009 (UTC)
"DNA studies have a problem in telling us about the MRCA. As Chang notes, the MRCA will be much more recent than any MRCA that could ever be found in DNA studies, even if one were to study the ancestry of every single gene. The reason being that we are considering people who are simply ancestors, through any route, whether or not any of their genes actually survived the journey. As the human genome consists of roughly 232 base pairs, the genetic contribution of a single ancestor may be flushed out of an individual's genome completely after 32 generations, or roughly 1,000 years.[4]."
What DNA studies are being referred to? This paragraph is mixing two ideas, "ways to find DNA" and the clarification that the MRCA is the unqualified MRCA, not the MRCA along a specific pathway. They don't belong in the same paragraph and the grammar needs improvement. —Preceding unsigned comment added by 67.175.124.153 ( talk) 04:03, 19 October 2010 (UTC)
"As the human genome consists of roughly 232 base pairs"... Hmm, maybe [unsigned] missed out a few orders of magnitude. The total human genome base-pair count runs into billions, as mentioned elsewhere on Wiki. DJMcC ( talk) 10:22, 21 April 2012 (UTC)
The article says "Other models reported in Rohde, Olson, and Chang (2004)[5] suggest that the MRCA of Western Europeans and people of Western European ancestry lived as recently as AD 1000." Could someone point out to me where in that article it mentions this? I simply cannot find it. If it's spurious, this needs pulled or changed. -- Calion | Talk 03:45, 4 May 2011 (UTC)
I think I know where that came from. It comes from the mislabeled Rohde paper incorrectly attributed as a 2005 submission to American Journal of Physical Anthropology. This much longer paper does discuss European MRCA among many other things. Sigh. I now need to fix references to this paper as well. Fred Hsu ( talk) 01:35, 10 June 2011 (UTC)
This is now fixed with the full rewrite of the article. I have not attempted to resurrect the Western Europe references from the 2003 paper. It's not a 2005 paper as stated before. It is 2003 and apparently not accepted. The PDF explicitly asks that it not be cited. So whoever cares deeply about this can investigate and resurrect the reference if they wish. Fred Hsu ( talk) 15:45, 12 June 2011 (UTC)
Discussion in the recent section "MCRA of Western Europeans" prompted me to examine changes made since 2009 more closely. I think it is time this article is cleaned up again. Following are for my own reference. Fred Hsu ( talk) 01:49, 9 June 2011 (UTC)
OK. Here are some problems with some of the edits in the past two years:
There are of course a lot of new, useful information. But I feel that no one has taken a wholistic view and organized these new writings into a coherent picture. In light of new information, and the 2004 Rohde article from Nature I've just got from my library, I think the Time Estimates section should be moved out of the initial sections. It should be presented after various types of MRCAs are discussed. I will clean up the article with these principles in mind. Fred Hsu ( talk) 00:55, 10 June 2011 (UTC)
Topics to be expanded and/or clarified outside of lead section:
Topics I removed but will add back once I figure out what they mean:
OK. I am done rewriting. The heavy listing is done. I invite everyone to examine changes and further refine this article now. I am including useful diff pages for reference. But since so many things have changed, if you really care you should use the History page to go through individual saved edits. I've provided useful edit summary to help you along. Fred Hsu ( talk) 15:40, 12 June 2011 (UTC)
GA toolbox |
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Reviewing |
Reviewer: Philcha ( talk) 09:50, 25 July 2011 (UTC)
I'll mark comments when I think they're resolved, highlight any that are unresolved when most others are done, and strike out any of comments that I later decide are mistaken. I'll sign each of my comments, so we can see who said what - please do the same.
I'll mark the review {{ inuse}} when I'm working on it, as edit conflicts are frustrating. If you think I've forgotten to remove {{ inuse}}, please leave a message at my Talk page. Please free to use {{ inuse}} with your own signature when you're working.
I'll read the article through first, then give comments. -- Philcha ( talk) 09:50, 25 July 2011 (UTC)
I think you have spent too much time focusing on what I see as a not-called-for campaign to discredit this article based on your own personal opinion on whether MRCA is needed. This is not part of the GA-review as the policy clearly states. It distracts from your very good opinion on how to improve this article which I highly respect. I formally ask that you strike out all sections on the 'merit' of this article. Thank you. Fred Hsu ( talk) 05:13, 29 July 2011 (UTC)
(sections)
I'll check with User:Dispenser/Checklinks and the DAB checker when the content is stable.
I'll check the images when the content is stable.
I review the lead last, to check that all of it is based on the main text.
Clearly this article is not yet GA. Despite our disagreement on 'merit' (which is not part of QA review), I think good ideas came out of the discussion. I will document these below, and work on the article. There is no point in keeping this QA review request alive while it undergoes dramatic surgery. After Philcha strikes out the paragraphs on 'merit', I will withdraw this request. Fred Hsu ( talk) 19:21, 31 July 2011 (UTC)
These suggestions should serve as a guide for further editing of this article. And when I try (or someone else tries) for GA next time, we can check off this list of items before actual GA review starts. Fred Hsu ( talk) 19:21, 31 July 2011 (UTC)
You still have not addressed the main problems, including:
Regretfully I conclude that this article is not of GA standard, and am marking it "Not listed". -- Philcha ( talk) 08:29, 5 August 2011 (UTC)
"In genetics, the most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended."
This, to me, is too vague. What does "most recent" mean? The common ancestor which died the fewest number of seconds ago? The common ancestor that was born the fewest number of seconds ago?
Or is "recent" based not on time, but on generations? The common ancestor to a set of organisms such that none of its descendants are also common ancestors to that set, but all of its ancestors are common ancestors to that set; or something like that?
I bring this up because a rigorous definition -- at least a clarification as to whether "recent" refers to time or to generations -- is exactly what I came to this artice to find. Gaiacarra ( talk) 02:57, 12 January 2012 (UTC)
From the opening sentence the article appears to be written by a child with a thesaurus: “In genetics” – Really? Why not “In biology,” or “In heredity” or “In genealogy” or “In evolution”? "(MRCA) is the most recent individual” – would that be the mom or the dad? “from which all organisms in the group are directly descended.” – Hmm “Directly” descended, versus the other kind?
Grown-up language such as: “Y-DNA network analysis of Y-STR haplotypes showing a non-star cluster indicates Y-STR variability due to multiple founding individuals,” is immediately followed by the childlike: “The descendants of Genghis Khan can be (traced) back to the time of Genghis Khan.”
Quote “The MRCA of living humans may have had many companions of both sexes.” A bit too salacious for the Wiki, no?
So much is made of the ”MCRA of everyone alive” and the ”identical ancestors point,” except what the difference might be. In fact, the whole article seems to have been taken over by techno-scienceo-jibberish. Reminds me of those amusing tourist signs in China like "deformed person toilet." Not quite the standard thoughtful people are looking for!
One author boldly states: “A common mistake made by the public as well as some authors is to refer to a proposed last common ancestor as an earliest ancestor.” Excuse me? Why is it a mistake? Who knows?
Dlong2 ( talk) 15:58, 5 July 2012 (UTC)
Rohde, Olson and Chang’s paper is granted only a small reference. But take away their contribution and this article is basically just a statement that the term “Most Recent Common Ancestor” can be represented by the letters M.R.C.A. I’d turn it into a stub with a reference to the paper and leave it at that. Dlong2 ( talk) 16:02, 5 July 2012 (UTC)
What about really remote people? I would have thought that the MRCA of all humans would have lived before the ancestors of non-Africans left Africa. that is 60-80-thousand years ago. -- Oddeivind ( talk) 21:58, 21 July 2012 (UTC)
Ok, I buy that it changes when people die without descendants because you can then clip them out of the human family tree. But new people born are by definition descendants of parents that already share a MRCA, so how can that change the population's MRCA? Consuelo D'Guiche ( talk) 12:31, 25 July 2012 (UTC)
I find this claim highly dubious: ""No matter the languages we speak or the color of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who labored to build the Great Pyramid of Khufu".[4]" I realise it is in a certain context, but, is there genetic evidence to support it, or is it merely maths based speculation??? It seems sort of unlikely that people from very opposite parts of the globe (say for instance a person from Africa having South American ancestry) would be related in this way, considering how these areas were populated and the amount of time it took people to travel pre-modern transport. I sort of question its presence for that reason^, that said I didn't read the paper so who knows :D — Preceding unsigned comment added by 72.228.182.191 ( talk) 03:34, 5 February 2012 (UTC)
The quote is the last sentence in the 2004 nature paper by Rohde, Olson and Chang that forms the basis of much of the material in the article and should be restored. Skates61 ( talk) 16:50, 3 June 2012 (UTC)
This raises an important issue. People find it very difficult to visualise the speed at which genes spread through the population. Possibly this is because languages and cultures remain geographically fixed. Perhaps this scepticism needs to be addressed in the article? — Preceding unsigned comment added by 194.150.177.249 ( talk) 11:16, 13 November 2013 (UTC)
Can we please get a geneticist to refute some of these young-earth claims of a 3,500 year-old human ancestor? It is really annoying to have people who claim that the earth is 6,000 years old to point at Wikipedia as their source, saying the human species originates at 3,500 years ago. I am not a regular contributor to Wikipedia, but this MRCA claims of 3500 years are unsupported by genetic evidence. — Preceding unsigned comment added by 63.229.209.73 ( talk) 06:53, 28 February 2016 (UTC)
I have made some changes in that section and, been no native english speaker, I absolute agree with having been corrected. But before erasing my contribution you should read carefully it and the article of IAP: this is NO SCIENCE at all, but a fallcious huge mountain of biased lies. This part of the article is absolutely false and fallacious. It tends to probe a thing in scientific-like lenguage with no scientific thought in it at all. People is not getting it SIMPLY BECAUSE ITS FALSE. There's no proof of such a thing as IAP to have happened in the past, for sure not MANDATORY and statistically VERY uneven. And if, by some very weird chance, this thing happened in the past it only could be in the population bottleneck of 75.000 years ago, BUT THERES NO GENETIC OR OTHER proof for that; or going back and back in life history up to the very beginning of pluri-cellular life.
What I clearly see is the long hand of religious crap underneath it all: the date of 5.000 years is such a joke in terms of MRCA and historical proofs of isolated populations that can only came from the crapy young earth creationists. I don't want and really don't think it worths my time fighting with fanatics or well paid guys (hi, Heritage guys!) to begin an editions war but I beg for someone with wiki authority to have an eye on this before we begin to hear this crap as a 'scientific proof for Adam and Eve and original Sin supported by wikipedia' in the media.
For the supporters of that crap: I wish all your ignorance presents its bill to you soon.
I just want you editors to read things critically and using your reason and mind. Please, please have an eye on this. — Preceding unsigned comment added by Cohelet ( talk • contribs) 20:49, 19 March 2013 (UTC)
I posted this to WT:GENETICS in response to the concerns of another editor which came up at WP:EAR: I actually just read the Rohde et al. article. It actually doesn't say anything about "5 to 10 thousand years ago". I tried to wrap my head around their statements to see if I could independently arrive at the article's 5 to 10k years ago claim via routine calculations, but could not. There are several statements about mean identical ancestor points arrived at in their simulations depending on changes to variables and the models, placing it at 2,158 BC, or 5,353 BC, and also noting that if people in Tasmania were totally reproductively isolated until 1803, then the latest possible identical ancestor point corresponds to the flooding of the Bass Strait some 9,000–12,000 years ago. Honestly, I think this is far enough away from routine calculations to make the claim in most recent common ancestor constitute original research. At the very least it probably needs in-text attribution to the authors. —/ Mendaliv/ 2¢/ Δ's/ 20:02, 20 May 2013 (UTC)
I am kind of losing hope for this page. I visit it every couple of years and clean up the worst attrition, but somehow, utter misconceptions always pop back almost immediately and remain unchallenged (in this case, since 2012). I'll try to clean up the page once again, but if you are watching it, please be wary of people adding "explanations" without citing additional sources. -- dab (𒁳) 13:06, 21 October 2016 (UTC)
The first sentence of the article says: In biology and genealogy, the most recent common ancestor [...] of any set of organisms is the most recent individual from which all organisms in a group are directly descended.
Focussing on genealogy here, and taking two (distant) cousins as any set of organisms
, the meaning of the term most recent individual
is possibly confusing. In (genetic) genealogy, MRCA often refers to 'most recent in terms of fewest generations back', and is used in the context of comparing DNA test results. For example, in the case of two second cousins who share a great-grandparent born in 1850, and who (via a different path) also share a greatgreat-grandparent born in 1860, the great-grandparent would be the MRCA for genetic genealogy purposes, but the greatgreat-grandparent would be the MRCA in the more common meaning discussed in this article. Generation gaps can be quite different in different ancestry lines, so this situation does happen in family trees, especially if you go back more generations than 3 or 4.
Since genealogy is mentioned in the lead sentence, I think it would be good if the article would clarify the exact meaning of "most recent". Does anyone have more knowledge about this? I can't find good sources that clearly define MRCA in genealogy context. Gap9551 ( talk) 18:42, 12 October 2017 (UTC)
[2] and [3]. Doug Weller talk 18:05, 17 July 2018 (UTC)
"for example, the MRCA of all Carnivora (i.e. the MRCA of "cats and dogs") is estimated to have lived of the order of 42 million years ago (Miacidae).[4]"
Carnivora are lions, tigers, bears, as well as canids. The MRCA of Canids is 60 million years ago. Canids include dogs, wolves, etc. — Preceding unsigned comment added by 208.80.117.214 ( talk) 09:32, 1 September 2018 (UTC)
In this section of the article is the following statement: "The age of the MRCA of all living humans is unknown. It is necessarily younger than the age of either the matrilinear or the patrilinear MRCA"
Does anyone else see a flaw in the logic of that statement? If the most recent common ancestor of all living humans is necessarily younger than the age of either the matrilinear or the patrilinear MRCA, then who/what was this ancestor, if they were neither female or male, and how did they pass down their genetics? If they were in fact, as all logic would suggest, either male or female, that would make them either the matrilinear or the patrilinear MRCA and thus the exact same age as one of them, not necessarily younger than both.
Therefore I must conclude one of the following:
As I said, I'm not an expert in this field, would someone that has more knowledge on the subject be willing to clean it up? — Preceding unsigned comment added by 198.47.204.197 ( talk) 14:01, 10 September 2018 (UTC)
[outdent] Just defining, not redefining. Many things that are impossible are so because they are so highly unlikely. Such as all the oxygen molecules in a room randomly moving to one end, suffocating someone at the other end.
I think the graphics you describe could be helpful. Knock yourself out. Rracecarr ( talk) 17:35, 10 September 2018 (UTC)
This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
Due to an inquiry in Last Common Ancestor I took a shot clearing up the confusion, maybe this will help.
An LCA is in fact the individual (or founding group) at the bifurcation point between two species. For us, this individual, which lived between two million and 40,000 bce, and no others contributed ALL of the genes that make up humanity. If we could pin the date down more closely we could probably call it "The MRCA between modern man and XXX" but we don't know the XXX.
Now fast forward to 2007. You and I and every person on earth could trace our ancestries back to around 2,000 years ago and find a common grandparent, aka The MRCA of All Mankind. Unlike the LCA, the genetic contribution of this ancestor to any one person is extremely small. This is because some ten million of his contemporaries ultimately get into the action.
Obviously the MRCA of All Mankind cannot be both of these individuals. Chang, et al, call the individual of 2,000 years ago the MRCA of All Mankind. So we call the other guy, the individual that began the species, the LCA (of all mankind).
Tom Schmal 06:19, 6 November 2007 (UTC)
This section states "The MRCA of humans alive today necessarily lived more recently than either." This is incorrect. If we imagine that there are four living humans, two males and two females, with matrilineal ancestor 3 generations back, with the males having the same father, then the "most recent common patrilineal ancestor of all living male humans" is more recent than the MRCA of all humans. Even if we use a definition of y chromosome Adam that includes the patrilineal ancestor of living females, this is still only exactly as recently, not more recently.
I'd suggest changing this to "The MRCA of humans alive today likely lived much more recently than either. By definition, the MT-MRCA is a common ancestor, but not likely the most recent. The Y-MRCA is by definition only the common ancestor of all males, but still likely to be much deeper in the past than the unrestricted MRCA, who may be an ancestor on any line."
But I don't have a citation for this. Can someone verify that the cite given for the original actually says this? I think someone may have simplified it, but using "necessarily" could be confusing. Kevinpet 06:12, 21 August 2007 (UTC)
from VfD:
Keep. Nunh-huh's fix makes the page work for me. I am replacing the VfD with a "stub" to save everybody's time. If you think otherwise, then please replace the VfD notice on the Most recent common ancestor page and post your objections above. Thanks. --- Rednblu 20:22, 2 Oct 2004 (UTC)
end moved discussion
I believe the confusion about this term is to do with how a single individual can pass on his or her DNA to all living individuals. The Most Recent Common Ancestor is a misnomer for the Most Recent Prolific Ancestor. Shared DNA merely means a single ancestral tree among a forest of ancestral trees has passed DNA on to all living individuals via prolific production of progeny who spread out through all the DNA trees of all living individuals. It is not indicative of a single source but merely a indicator of a single common point of some source DNA among many sources of DNA. IF you were to talk about multiple points of infection and view this shared DNA as if it were a virus you would realize it is just one virus among many but that it has infected everyone through time. It can then be viewed as an indicator of a very mobile population group who shared a common ancestral root and who seeded their DNA into many DNA trees throughout all know population groups. So the MRCA aka MRPA becomes an indicator of the most recent spread of a single source of DNA among all groups.
—The preceding unsigned comment was added by 210.209.65.40 ( talk) 09:25, 5 April 2007 (UTC).
I believe that the MRCA is purely a mathematical model which accounts for mutation rates, migration, etc, but has nothing whatever to do with individuals taking genealogical DNA tests. If I'm correct then the second paragraph of this article should be revised.
One alternative might be the insertion of a new paragraph to distinguish between meanings. Here's a stab at it:
The term is used in two ways. In ordinary usage the most recent common ancestor refers to:
- An individual identified as the most recent ancestor of two persons -- by DNA testing of two males or two females, or by traditional genealogy.
In scholarly usage, however, it has another meaning:.
- An individual who lived at a time which has been estimated by a mathematical model accounting for the rate of mutation (and sometimes also the rates of migration, inbreeding, etc.) and who is the most recent ancestor of all males, all females, or all living persons.
Any comments, objections, etc.? AnonUser 14:49, 14 October 2005 (UTC)
I agree with the focus as is. The article is confusing, however, because it uses multiple definitions of MRCA. I propose that the article clearly distinguish among them up front. AnonUser 19:24, 14 October 2005 (UTC)
Ah so -- you are correct. Perhaps its confusing because the examples are so dissimilar, without language tieing them together. If its confusing to me, its probably confusing to other readers too. Maybe a little tweaking would help. AnonUser 02:57, 15 October 2005 (UTC)
Long discussion here. My issue is that on one hand we are saying the MRCA may have lived in the common era, on the other hand we are saying MRCA lived in paleolithic, defined in that article as 2.5 MYA to 10 KYA. This is not helpful at all, we need a tighter bound. Since we know from the y-chromosomal Adam article that he lived just 60 KYA, can we at least deduce that MRCA was more recent than that? This would place MRCA between 60 KYA and 1000 CE. If no counter-comments I will update. Skates61 ( talk) 23:29, 27 June 2008 (UTC)
Ok, rwr8189 was correct in reverting my blank out of this section- the cited articles are in Nature and have subsequently been cited by others, and after reading them they certainly make a case worthy of discussion. However, I feel there two corrections should be considered: 1. in the '04 article they use the admittedly naive system in which any two humans can randomly breed in any given generation (this yields the 1000 CE date). This simplification should be explicitly stated as a model, or the very-recent daate should be dropped in lieu of the same group's more advanced and recent estimate (the 2005 nature paper). 2. Make the point that for a given non-isolated population, the MRCA is surprisingly recent, but also that the existence of even a single isolated population or insufficiently mixed population implies a much earlier MRCA (though still not the tens of thousands of years I had expected.) coments? Jodine Sparks 20:20, 3 July 2007 (UTC)
This section is based on a single study amongst a fairly large field of research, and the results of said study are patently false. Until someone can rewrite it with actual 'time estimates' that correspond to a older MRCA than 1000AD (which is obvious), I just going to comment it out. I hope this is not too presumptuous, but this section as it stands is only presenting known misinformation.
Jodine Sparks
16:45, 29 January 2007 (UTC)
To: EamonnPKeane. Kindly state all your assumptions, including:
The "historical times" estimate is patently ridiculous, imho; it seems they used some sort of diffusion to model human migration. The statement
betrays the preceding estimate: We defined the MRCA as that of all humans alive today, so what do you mean "if one attempts to take into account tribes in Central Africa"? Unless you want to argue they are not human, you'll have no choice but to take them into account. I can easily believe the MRCA of Europeans (or even continental Eurasians) lived in the Common Era. It is inconceivable that the MRCA of all humans lived after 3000 BC: A single isolated tribe (Pygmies, Aboriginals, Indonesian bushmen, take your pick) pushes the MRCA back to the Paleolithic. I can easily imagine, even, that the MRCA of 99% of humans alive today lived in historical times, but it takes just a single surviving individual from an isolated lineage to render that calculation obsolete. dab (ᛏ) 09:56, 3 January 2006 (UTC)
I think that the suggestion of a human MRCA having lived from between 3000BC to 1000AD(!) is absolutely ridiculous. What kind of pseudo-science must this be? Think about it, if it were true, there would for example be no single 100% pure-blooded Native American alive today (since the Native Americans had reached and spread throughout the American continents well before 3000BC, a possible exception to this being the Eskimos) which, be they few, I think there are.
I agree that this is ludicrous. Are we talking about all humans or aren't we? Ancestors of Aborigines are believed to have arrived in Australia between 40k and 50k years ago: http://en.wikipedia.org/wiki/Indigenous_Australians I have a hard time believing that I, a white man, have a common ancestor with a black aborigine as recently as 4000 years ago. Who wrote this crap? Additionally, that time estimate 3000BC to 1000AD suspiciously encompasses when the Christian or Hebrew "creation" would have taken place. Zmbe 06:02, 11 March 2006 (UTC)
The whole concept of a purely mathematical MRCA is both unscientific and useless. It assumes the nonsensical notion that one's ancestors double with each generation backward, so that, for example, 20 generations ago I had a million (2^20) ancestors, or almost that many. But the human genome contains no more than 25,000 genes! In other words, no matter how many generations back I go, I cannot have any more than 25,000 genuine ancestors--i.e., ancestors who have actually contributed to my genome. All the other thousands or millions are ancestors on paper only, and have no scientific or practical significance.
Let's now even consider those 25,000 distant ancestors. Each contributed as little as a single gene to my genome. Big deal! Such an ancestor still has no practical significance to those living today, unless perchance that ancestor contributed a crucial improvement to humanity that we now all share. But I know of no such great improvement in the human genome within the last 70,000 years.
The bottom line here is that, beyond 20 generations, the ONLY ancestors that are of practical significance to humans living today are the two ancestors who contributed a SIGNIFICANT quantity of genetic material: the Y-chromosome ancestor and the mitochondrial DNA ancestor. Thus, it is for good reason that those interested in distant genealogy (beyond 20 generations) focus on the strict patrilineal and matrilineal lines.
"The whole concept of a purely mathematical MRCA is both unscientific and useless. It assumes the nonsensical notion that one's ancestors double with each generation backward, so that, for example, 20 generations ago I had a million (2^20) ancestors, or almost that many. But the human genome contains no more than 25,000 genes! In other words, no matter how many generations back I go, I cannot have any more than 25,000 genuine ancestors--i.e., ancestors who have actually contributed to my genome. All the other thousands or millions are ancestors on paper only, and have no scientific or practical significance."
Good point, except that on top of what you mentioned, there is an extremely high degree of redundancy amongst those 2^20 ancestors. In other words, not only do some ancestors contribute zero genes to you (as you pointed out), but also, a given ancestor from 20 generations back is most likely your ancestor many, many times over (so, due to the redundancy factor, the number of actual ancestors at a given number of generations back is way less than the mathematical value).
"The bottom line here is that, beyond 20 generations, the ONLY ancestors that are of practical significance to humans living today are the two ancestors who contributed a SIGNIFICANT quantity of genetic material: the Y-chromosome ancestor and the mitochondrial DNA ancestor. Thus, it is for good reason that those interested in distant genealogy (beyond 20 generations) focus on the strict patrilineal and matrilineal lines."
Here you are absolutely wrong. Mitochondrial DNA does not code for anything except mitochondria, and the y-chromosome (in males only) is far from the only chromosome that codes for traits. It is true that for a large number of generations ago, only some of an individual's ancestors of that generation contributed to his/her genetic makeup. However, it is NOT the case that these individuals are restricted to the direct maternal and paternal lines. Some of the genes that make me distinct could have come to me via my mother's father's father's mother's father's mother's mother's .... It is incorrect to say that one's genes come strictly from the direct male and direct female lines (else, why do some people clearly take after a mother's father or a father's mother?!?)
—Preceding
unsigned comment added by
151.207.242.4 (
talk)
02:18, 24 October 2007 (UTC)
I've added a section on MRCA of different species, and referenced Richard Dawkins' book, The Ancestor's Tale. I recommend it, especially to those who have contributed to the discussion above. He places a lower-bound of 13,000 years on the age of the MRCA of all humanity (with a rather sad proviso – see later). This is because it is known that the native population of Tasmania was physically separated from the rest of the world 13,000 years ago, and therefore we could not share a later ancestor with them. The only problem is that the Europeans who colonised Tasmania treated them as vermin and exterminated the whole lot by 1876. Also, FWIW, Dawkins reckons on an upper limit of 100,000 years as the age of the MRCA of all of us. -- Portnadler 17:23, 8 May 2006 (UTC)
What sort of social rank would one have to bear in their family, in order to be a descendent of either?
How far up the totem pole, would you say?
This is intended to have broad answers and based on gradients of time and population, not going into specifics about exact descendents. About how common is their descent in the English or British genepool today?
I've noticed that American Presidents don't descend from either king, but the most common recent royal ancestor shared by many of us is Edward III. How common is it for anybody in the English or British genepool, to have a Protestant royal ancestor?
There is a general cutoff, isn't there?
Is it because of fratricide in the Wars of the Roses, the Tudors' "new men", or the Union of the Crowns, or the parliamentary union under Queen Anne (I can't think of any non-royal family descent from the Hanoverians within the UK)?
I'm thinking that there is a big difference between Plantagenet and Tudor descents, that the commons in all likelihood have the former and the latter is held by the lords. (just generally speaking) Then again, Tudor descent in the Welsh must be higher in general. I am further curious about pre-Royal Tudor blood in Anglo-British people today, since the status and/or concept of Welsh royalty/nobility is rather hazy in my mind. I found the Blevins aka Ap Bleddyn family of Powys in my ancestry, but have no real idea on what to make of it--or any other Welsh "native aristocracy". I might be able to find Stewart descent somewhere, from way back when. What percentage of Hanoverian background do you think that German colonists had in America?
On the British side, I have to go as far back as Welf himself...but any recent genetic relationship with the Hanoverians or the counts of Nassau are completely obscure. How does one research those other colonial people, such as the Hessians?
UK genealogy is relatively easy when focusing on English (and French) ancestries. What would a "national person" of Jerusalem (or Antioch, for example) in Crusader times be known as?
We say "American" for those Founders, but was there such a nationality-term for the Crusaders in their own domains?
I guess the term is supposed to be Levantine/Outremer, or "Crusader" as our national heritage says "Colonist"...
IP Address 11:48, 9 May 2006 (UTC)
I have a question:
After reading the article I was happy to see how closely related we are. I would really appreciate it if someone has more detailed information on population. I just can't get past the fact that the article seems to focus on 6.5 billion people. Our ancestors came and went throughout history. From the point of our MRCA's existance to present more than 6.5 billion people have lived. The town where I lived has an approximate population of 100,000 but from the day the founder came and died to present I can't even fathom how many people have lived here. Can someone help me find the numbers I need to understand?
Approximate total of humans since time of our MRCA:???
83.219.199.121 00:38, 23 July 2006 (UTC)Leif
If anyone doesnt have a significant other because they have come to terms with the fact that we are all related let me put this into your heads. I am almost positive that somewhere out there in the universe that there is another species that are exactly like us, humonoid, but do not come from a genetic line that comes from this planet. It is an infinite universe. The distance between them (a mating partner not of our gentic line) and us is trillions of light years away.-- RCJACOBS100 23:55, 16 September 2006 (UTC)Robert Curley Jacobs
I thought this was meant to describe a graph? It clearly descibes a tree to me: "...there will eventually be an MRCA from whom it is possible to trace a path of direct descendants all the way down to every living person at the bottom..." - THAT is a tree. (by 90.242.58.236 on 06:44, February 19, 2007)
User:Robin S added the following which I just removed:
Indeed, within twenty generations, most descendants of an individual will not have inherited any of their genes from a given ancestor since there will be far more ancestors than genes. Since considerably more than twenty generations have passed since the hypothesized date of the human MRCA, it is possible that not a single human gene present today was inherited from that individual.
It is not immediately clear that in 20 generations the number of ancestors will be greater than number of genes. Please see the other paragraphs in the same session where 'tree' vs. 'graph' was discussed. Note that many ancestors are shared. Also see the chapter 'All Africa and her progenies' in River out of Eden. But perhaps you are right. We just need to find a reference which shows this to be true, taking into account the graph nature of human ancestry. Fred Hsu 17:48, 21 March 2007 (UTC)
In page 60-61 of The Ancestor's Tale, Dawkins states that he believes that the almost identical ABO blood types in humans and chimps are examples of trans-specific polymorphism. That is, a type-B human may actually be more closely related to type-B chimp than type-B human is related to type-B human, from the perspective of the genes (or alleles) responsible for the antigens.
I wanted to add this to the article to indicate that by tracing ancestry based on other genes, we may actually reach startling conclusions about our most recent common ancestor. That is, I may share a type-B MRCA with an ape, while a type-B person shares another type-B MRCA with another ape.
But after some basic research on this topic, I found that Dawkins was probably wrong on this account. First, chimps don't have blood-type B. They only have A and O. Other primates have combinations of A, B, AB and O, with the exception of macaques which has all of them. This does not necessarily indicate the B-type in human is the same as B-type in apes, for instance. It could be that there was an original type-A inherited by all apes, including human. From there other blood-types developed. And it so happened that type-B and type-O are stable variants which appeared independently in different species.
Most of the studies on blood types across apes I could read online (without paying for subscriptions) were rather old (decades-old). The two recent ones I could read did not support Dawkins' view:
Perhaps I need to get this book?
Can someone shed more light on this topic? Fred Hsu 23:33, 1 June 2007 (UTC)
Someone created a new article called Most ancient common ancestor. Notice that it is ancient, not recent. It appears to be a new name coined by the author without research backing (i.e. original research). I nominated that page for deletion. Please visit Wikipedia:Articles for deletion/Most ancient common ancestor if you wish to participate in the discussion. Again, please note that I am not nominating the Most Recent Common Ancestor article for deletion; I am nominating the newly created Most Ancient Common Ancestor. Fred Hsu 05:41, 21 July 2007 (UTC)
people for some reason seem to have a lot of difficulty coming to terms with the concept, even if great pains are taken to explain it. I just noted flawed material at Last Common Ancestor, an article that should probably be merged here. dab (𒁳) 11:16, 23 July 2007 (UTC)
Since an organism can have a copy of a gene from each parent, and these parents can share a common ancestor, does this mean that genes have ancestor and progeny graphs rather than trees? Or are two copies of a gene in a single organism not considered to be a single vertex in a gene ancestor/progeny diagram? Wikimedes ( talk) 06:54, 18 November 2007 (UTC)
Lklundin introduced two sets of changes to the article. The first set of changes is about MRCA being a set of people as opposed to a single individual. I understand the reason behind these changes. While these changes seem rational, it is not how MRCA is typically described. Since the MRCA is not a real person, but is statistically computed, traditionally we use a single person to represent this idea. If we are going to suddenly define MRCA as a set of people, then we should start to call it 'most recent common ancestors' with an 's' at the end. We should also rewrite the whole article to be consistent with this change. We should also refer to African Eves, not the African Eve, as two sisters might have had identical mtDNA and together covered all living people on Earth today.
I am going to change the first paragraph back to the way it was, ok? Fred Hsu ( talk) 00:22, 26 November 2007 (UTC)
Thank for the changes on calculation, by the way. It makes the paragraph better. Fred Hsu ( talk) 00:33, 26 November 2007 (UTC)
A section of notable coancestors, whould be really good both theoretical (roundish flatworm, Ohno's Cambrian pananimalia genomes, urcrustacean) and fossil (Wiwaxia, Hallucigenia, archaeopterix etc...)-- Squidonius ( talk) 17:26, 12 December 2007 (UTC)
Can we have something added in layman's terms? There is no real reference to what the subject matter is about and it doesn't explain clearly what the MRCA is actually for, it just jumps straight into jargon. JayKeaton ( talk) 15:36, 8 August 2008 (UTC)
There is certainly good information here, but it could be quite confusing, because at FT-DNA, they are computing time to direct paternal MRCA for two persons who have kit results. This is not the same as the MRCA on any route, which is the focus of this article. FT-DNA does not explain the distinction. Keep the link? Qualify it? Remove it? What's everyone's thoughts on this? —Preceding unsigned comment added by Skates61 ( talk • contribs) 23:36, 17 September 2008 (UTC)
From the article: "The ancestry tree is thus not strictly a tree, but a directed, mostly-acyclic graph." Am I missing something here? Barring any sort of a time-travel accident, I don't see how cycles are possible. 70.68.114.213 ( talk) 19:15, 22 March 2009 (UTC)
Hey guys - I'm a layman who is struggling to picture a last common ancestor in "family tree" terms. If the last common ancestor was part of a population of (say for the sake of argument) 10,000 humans, then does that mean that the other 9,999 don't have any descendants alive today? If not, would it be possible to produce some kind of family tree-style graphic of a mini population that has the last common ancestor labelled in an illuminatory way? Señor Service ( talk) 21:37, 5 June 2009 (UTC)
I don't get how the MRCA can be someone other than the Y-Chromosomal Adam or Mitochondrial Eve (whoever's more recent). — Preceding unsigned comment added by Deathmare ( talk • contribs) 16:24, 6 June 2011 (UTC)
Thanks for the article all. Just a question to help my understanding if I may, as I like a lot of people find this tricky to comprehend! Is it true to say that, theoretically, tracing back to the identical ancestors point for a population could give you a population that would be considered a different species? I'm thinking this situation could arise if one has to trace back a particularly long way back in time, or if the present population has come to be through convergent evolution. Kurisu rs ( talk) 13:40, 25 July 2011 (UTC)
It is clear from questions posted on the talk page that we need illustrations. If you have ideas or will be producing illustrations, please first post here so that we don't duplicate efforts. Fred Hsu ( talk) 04:23, 6 June 2009 (UTC)
But first I would like to review changes to this article since I last looked at/edited it. We can use some clean up. Also, I will probably resolve the long-standing call to merge Last Common Ancestor into this MRCA article. If you are interested in helping, please first read this talk section from LCA for where we stood by Dec 2007 on this issue. Fred Hsu ( talk) 04:23, 6 June 2009 (UTC)
"DNA studies have a problem in telling us about the MRCA. As Chang notes, the MRCA will be much more recent than any MRCA that could ever be found in DNA studies, even if one were to study the ancestry of every single gene. The reason being that we are considering people who are simply ancestors, through any route, whether or not any of their genes actually survived the journey. As the human genome consists of roughly 232 base pairs, the genetic contribution of a single ancestor may be flushed out of an individual's genome completely after 32 generations, or roughly 1,000 years.[4]."
What DNA studies are being referred to? This paragraph is mixing two ideas, "ways to find DNA" and the clarification that the MRCA is the unqualified MRCA, not the MRCA along a specific pathway. They don't belong in the same paragraph and the grammar needs improvement. —Preceding unsigned comment added by 67.175.124.153 ( talk) 04:03, 19 October 2010 (UTC)
"As the human genome consists of roughly 232 base pairs"... Hmm, maybe [unsigned] missed out a few orders of magnitude. The total human genome base-pair count runs into billions, as mentioned elsewhere on Wiki. DJMcC ( talk) 10:22, 21 April 2012 (UTC)
The article says "Other models reported in Rohde, Olson, and Chang (2004)[5] suggest that the MRCA of Western Europeans and people of Western European ancestry lived as recently as AD 1000." Could someone point out to me where in that article it mentions this? I simply cannot find it. If it's spurious, this needs pulled or changed. -- Calion | Talk 03:45, 4 May 2011 (UTC)
I think I know where that came from. It comes from the mislabeled Rohde paper incorrectly attributed as a 2005 submission to American Journal of Physical Anthropology. This much longer paper does discuss European MRCA among many other things. Sigh. I now need to fix references to this paper as well. Fred Hsu ( talk) 01:35, 10 June 2011 (UTC)
This is now fixed with the full rewrite of the article. I have not attempted to resurrect the Western Europe references from the 2003 paper. It's not a 2005 paper as stated before. It is 2003 and apparently not accepted. The PDF explicitly asks that it not be cited. So whoever cares deeply about this can investigate and resurrect the reference if they wish. Fred Hsu ( talk) 15:45, 12 June 2011 (UTC)
Discussion in the recent section "MCRA of Western Europeans" prompted me to examine changes made since 2009 more closely. I think it is time this article is cleaned up again. Following are for my own reference. Fred Hsu ( talk) 01:49, 9 June 2011 (UTC)
OK. Here are some problems with some of the edits in the past two years:
There are of course a lot of new, useful information. But I feel that no one has taken a wholistic view and organized these new writings into a coherent picture. In light of new information, and the 2004 Rohde article from Nature I've just got from my library, I think the Time Estimates section should be moved out of the initial sections. It should be presented after various types of MRCAs are discussed. I will clean up the article with these principles in mind. Fred Hsu ( talk) 00:55, 10 June 2011 (UTC)
Topics to be expanded and/or clarified outside of lead section:
Topics I removed but will add back once I figure out what they mean:
OK. I am done rewriting. The heavy listing is done. I invite everyone to examine changes and further refine this article now. I am including useful diff pages for reference. But since so many things have changed, if you really care you should use the History page to go through individual saved edits. I've provided useful edit summary to help you along. Fred Hsu ( talk) 15:40, 12 June 2011 (UTC)
GA toolbox |
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Reviewing |
Reviewer: Philcha ( talk) 09:50, 25 July 2011 (UTC)
I'll mark comments when I think they're resolved, highlight any that are unresolved when most others are done, and strike out any of comments that I later decide are mistaken. I'll sign each of my comments, so we can see who said what - please do the same.
I'll mark the review {{ inuse}} when I'm working on it, as edit conflicts are frustrating. If you think I've forgotten to remove {{ inuse}}, please leave a message at my Talk page. Please free to use {{ inuse}} with your own signature when you're working.
I'll read the article through first, then give comments. -- Philcha ( talk) 09:50, 25 July 2011 (UTC)
I think you have spent too much time focusing on what I see as a not-called-for campaign to discredit this article based on your own personal opinion on whether MRCA is needed. This is not part of the GA-review as the policy clearly states. It distracts from your very good opinion on how to improve this article which I highly respect. I formally ask that you strike out all sections on the 'merit' of this article. Thank you. Fred Hsu ( talk) 05:13, 29 July 2011 (UTC)
(sections)
I'll check with User:Dispenser/Checklinks and the DAB checker when the content is stable.
I'll check the images when the content is stable.
I review the lead last, to check that all of it is based on the main text.
Clearly this article is not yet GA. Despite our disagreement on 'merit' (which is not part of QA review), I think good ideas came out of the discussion. I will document these below, and work on the article. There is no point in keeping this QA review request alive while it undergoes dramatic surgery. After Philcha strikes out the paragraphs on 'merit', I will withdraw this request. Fred Hsu ( talk) 19:21, 31 July 2011 (UTC)
These suggestions should serve as a guide for further editing of this article. And when I try (or someone else tries) for GA next time, we can check off this list of items before actual GA review starts. Fred Hsu ( talk) 19:21, 31 July 2011 (UTC)
You still have not addressed the main problems, including:
Regretfully I conclude that this article is not of GA standard, and am marking it "Not listed". -- Philcha ( talk) 08:29, 5 August 2011 (UTC)
"In genetics, the most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended."
This, to me, is too vague. What does "most recent" mean? The common ancestor which died the fewest number of seconds ago? The common ancestor that was born the fewest number of seconds ago?
Or is "recent" based not on time, but on generations? The common ancestor to a set of organisms such that none of its descendants are also common ancestors to that set, but all of its ancestors are common ancestors to that set; or something like that?
I bring this up because a rigorous definition -- at least a clarification as to whether "recent" refers to time or to generations -- is exactly what I came to this artice to find. Gaiacarra ( talk) 02:57, 12 January 2012 (UTC)
From the opening sentence the article appears to be written by a child with a thesaurus: “In genetics” – Really? Why not “In biology,” or “In heredity” or “In genealogy” or “In evolution”? "(MRCA) is the most recent individual” – would that be the mom or the dad? “from which all organisms in the group are directly descended.” – Hmm “Directly” descended, versus the other kind?
Grown-up language such as: “Y-DNA network analysis of Y-STR haplotypes showing a non-star cluster indicates Y-STR variability due to multiple founding individuals,” is immediately followed by the childlike: “The descendants of Genghis Khan can be (traced) back to the time of Genghis Khan.”
Quote “The MRCA of living humans may have had many companions of both sexes.” A bit too salacious for the Wiki, no?
So much is made of the ”MCRA of everyone alive” and the ”identical ancestors point,” except what the difference might be. In fact, the whole article seems to have been taken over by techno-scienceo-jibberish. Reminds me of those amusing tourist signs in China like "deformed person toilet." Not quite the standard thoughtful people are looking for!
One author boldly states: “A common mistake made by the public as well as some authors is to refer to a proposed last common ancestor as an earliest ancestor.” Excuse me? Why is it a mistake? Who knows?
Dlong2 ( talk) 15:58, 5 July 2012 (UTC)
Rohde, Olson and Chang’s paper is granted only a small reference. But take away their contribution and this article is basically just a statement that the term “Most Recent Common Ancestor” can be represented by the letters M.R.C.A. I’d turn it into a stub with a reference to the paper and leave it at that. Dlong2 ( talk) 16:02, 5 July 2012 (UTC)
What about really remote people? I would have thought that the MRCA of all humans would have lived before the ancestors of non-Africans left Africa. that is 60-80-thousand years ago. -- Oddeivind ( talk) 21:58, 21 July 2012 (UTC)
Ok, I buy that it changes when people die without descendants because you can then clip them out of the human family tree. But new people born are by definition descendants of parents that already share a MRCA, so how can that change the population's MRCA? Consuelo D'Guiche ( talk) 12:31, 25 July 2012 (UTC)
I find this claim highly dubious: ""No matter the languages we speak or the color of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who labored to build the Great Pyramid of Khufu".[4]" I realise it is in a certain context, but, is there genetic evidence to support it, or is it merely maths based speculation??? It seems sort of unlikely that people from very opposite parts of the globe (say for instance a person from Africa having South American ancestry) would be related in this way, considering how these areas were populated and the amount of time it took people to travel pre-modern transport. I sort of question its presence for that reason^, that said I didn't read the paper so who knows :D — Preceding unsigned comment added by 72.228.182.191 ( talk) 03:34, 5 February 2012 (UTC)
The quote is the last sentence in the 2004 nature paper by Rohde, Olson and Chang that forms the basis of much of the material in the article and should be restored. Skates61 ( talk) 16:50, 3 June 2012 (UTC)
This raises an important issue. People find it very difficult to visualise the speed at which genes spread through the population. Possibly this is because languages and cultures remain geographically fixed. Perhaps this scepticism needs to be addressed in the article? — Preceding unsigned comment added by 194.150.177.249 ( talk) 11:16, 13 November 2013 (UTC)
Can we please get a geneticist to refute some of these young-earth claims of a 3,500 year-old human ancestor? It is really annoying to have people who claim that the earth is 6,000 years old to point at Wikipedia as their source, saying the human species originates at 3,500 years ago. I am not a regular contributor to Wikipedia, but this MRCA claims of 3500 years are unsupported by genetic evidence. — Preceding unsigned comment added by 63.229.209.73 ( talk) 06:53, 28 February 2016 (UTC)
I have made some changes in that section and, been no native english speaker, I absolute agree with having been corrected. But before erasing my contribution you should read carefully it and the article of IAP: this is NO SCIENCE at all, but a fallcious huge mountain of biased lies. This part of the article is absolutely false and fallacious. It tends to probe a thing in scientific-like lenguage with no scientific thought in it at all. People is not getting it SIMPLY BECAUSE ITS FALSE. There's no proof of such a thing as IAP to have happened in the past, for sure not MANDATORY and statistically VERY uneven. And if, by some very weird chance, this thing happened in the past it only could be in the population bottleneck of 75.000 years ago, BUT THERES NO GENETIC OR OTHER proof for that; or going back and back in life history up to the very beginning of pluri-cellular life.
What I clearly see is the long hand of religious crap underneath it all: the date of 5.000 years is such a joke in terms of MRCA and historical proofs of isolated populations that can only came from the crapy young earth creationists. I don't want and really don't think it worths my time fighting with fanatics or well paid guys (hi, Heritage guys!) to begin an editions war but I beg for someone with wiki authority to have an eye on this before we begin to hear this crap as a 'scientific proof for Adam and Eve and original Sin supported by wikipedia' in the media.
For the supporters of that crap: I wish all your ignorance presents its bill to you soon.
I just want you editors to read things critically and using your reason and mind. Please, please have an eye on this. — Preceding unsigned comment added by Cohelet ( talk • contribs) 20:49, 19 March 2013 (UTC)
I posted this to WT:GENETICS in response to the concerns of another editor which came up at WP:EAR: I actually just read the Rohde et al. article. It actually doesn't say anything about "5 to 10 thousand years ago". I tried to wrap my head around their statements to see if I could independently arrive at the article's 5 to 10k years ago claim via routine calculations, but could not. There are several statements about mean identical ancestor points arrived at in their simulations depending on changes to variables and the models, placing it at 2,158 BC, or 5,353 BC, and also noting that if people in Tasmania were totally reproductively isolated until 1803, then the latest possible identical ancestor point corresponds to the flooding of the Bass Strait some 9,000–12,000 years ago. Honestly, I think this is far enough away from routine calculations to make the claim in most recent common ancestor constitute original research. At the very least it probably needs in-text attribution to the authors. —/ Mendaliv/ 2¢/ Δ's/ 20:02, 20 May 2013 (UTC)
I am kind of losing hope for this page. I visit it every couple of years and clean up the worst attrition, but somehow, utter misconceptions always pop back almost immediately and remain unchallenged (in this case, since 2012). I'll try to clean up the page once again, but if you are watching it, please be wary of people adding "explanations" without citing additional sources. -- dab (𒁳) 13:06, 21 October 2016 (UTC)
The first sentence of the article says: In biology and genealogy, the most recent common ancestor [...] of any set of organisms is the most recent individual from which all organisms in a group are directly descended.
Focussing on genealogy here, and taking two (distant) cousins as any set of organisms
, the meaning of the term most recent individual
is possibly confusing. In (genetic) genealogy, MRCA often refers to 'most recent in terms of fewest generations back', and is used in the context of comparing DNA test results. For example, in the case of two second cousins who share a great-grandparent born in 1850, and who (via a different path) also share a greatgreat-grandparent born in 1860, the great-grandparent would be the MRCA for genetic genealogy purposes, but the greatgreat-grandparent would be the MRCA in the more common meaning discussed in this article. Generation gaps can be quite different in different ancestry lines, so this situation does happen in family trees, especially if you go back more generations than 3 or 4.
Since genealogy is mentioned in the lead sentence, I think it would be good if the article would clarify the exact meaning of "most recent". Does anyone have more knowledge about this? I can't find good sources that clearly define MRCA in genealogy context. Gap9551 ( talk) 18:42, 12 October 2017 (UTC)
[2] and [3]. Doug Weller talk 18:05, 17 July 2018 (UTC)
"for example, the MRCA of all Carnivora (i.e. the MRCA of "cats and dogs") is estimated to have lived of the order of 42 million years ago (Miacidae).[4]"
Carnivora are lions, tigers, bears, as well as canids. The MRCA of Canids is 60 million years ago. Canids include dogs, wolves, etc. — Preceding unsigned comment added by 208.80.117.214 ( talk) 09:32, 1 September 2018 (UTC)
In this section of the article is the following statement: "The age of the MRCA of all living humans is unknown. It is necessarily younger than the age of either the matrilinear or the patrilinear MRCA"
Does anyone else see a flaw in the logic of that statement? If the most recent common ancestor of all living humans is necessarily younger than the age of either the matrilinear or the patrilinear MRCA, then who/what was this ancestor, if they were neither female or male, and how did they pass down their genetics? If they were in fact, as all logic would suggest, either male or female, that would make them either the matrilinear or the patrilinear MRCA and thus the exact same age as one of them, not necessarily younger than both.
Therefore I must conclude one of the following:
As I said, I'm not an expert in this field, would someone that has more knowledge on the subject be willing to clean it up? — Preceding unsigned comment added by 198.47.204.197 ( talk) 14:01, 10 September 2018 (UTC)
[outdent] Just defining, not redefining. Many things that are impossible are so because they are so highly unlikely. Such as all the oxygen molecules in a room randomly moving to one end, suffocating someone at the other end.
I think the graphics you describe could be helpful. Knock yourself out. Rracecarr ( talk) 17:35, 10 September 2018 (UTC)