Talk:Most recent common ancestor

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[edit] MRCA and LCA compared

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)

You have posted the exact same comment here and in the talk page of LCA. Can we please keep all discussions on the same page please. Let's discuss it at Talk:Last Common Ancestor#Confusing article to avoid further confusion. You will find my original comment on that page, and new stuff I am about to post now. Fred Hsu 23:15, 6 November 2007 (UTC)

[edit] Patrilineal and matrilineal ancestry

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)

MRCA is calculated based on statistical analysis of gene data. It assumes the current population size of humans. That is, we are not talking about 2 males and 2 females. We are talking about billions of poeple. Statistically speaking, unqualified MRCA must be more recent than the other two. Fred Hsu 14:23, 21 August 2007 (UTC)
Yep. The probability that the MRCA is the same as the matrilinial or patrilineal MRCA is not technically zero, but is vanishingly small. The same applies to molecules of gas. The probability of all the oxygen molecules happening to leave your area of the room, suffocating you, is not zero. But in practice, it never happens. Rracecarr 19:12, 21 August 2007 (UTC)

[edit] From vfd

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)

Nonsense page currently. Possibly a valid topic combining general principles from both Mitochondrial Eve and Y-chromosomal Adam. New page by a new citizen, but this page may be part of a prank--see questions on bottom of Talk:Mitochondrial Eve. ---Rednblu 19:15, 2 Oct 2004 (UTC)
  • keep. This is a well known topic in genetics, and it's distinct from "Mitochondrial Eve" and "Y-chromosomal Adam": the MRCA of present-day humanity is considerably more recent than either "Eve" or "Adam" - Nunh-huh 19:22, 2 Oct 2004 (UTC)
  • Keep. I don't see why the current page is nonsense. It's a bit stubby. See also Genealogy (section The "Maximum Relationship"), which contains material that can put here (after it is corrected). Eugene van der Pijll 19:22, 2 Oct 2004 (UTC)
  • Keep. Valid topic, well-written. RickK 19:40, Oct 2, 2004 (UTC)
  • Keep. Notable concept, good article. — Gwalla | Talk 21:34, 2 Oct 2004 (UTC)
  • Keep Looks like a good topic and article to me... --Asmodai 15:47, Oct 3, 2004 (UTC)

end moved discussion

[edit] MRCA should be renamed to MRPA

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).

Wikipedia is not a place for original research. If you can find published papers calling concestors MRPAs, then please update the article. Otherwise, we need to stick to names used in the scientific community. Besides, what you described was MRCA via a particular gene path (such as mt-mrca or Y-mrca). When unqualified, MRCA refers to the common ancestor reached via either parent. Fred Hsu 02:55, 6 April 2007 (UTC)

[edit] Two meanings?

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)

The article, by focusing on the phrase "the MRCA of X", is better as is. You seem to be confusing "the MRCA of X" with "an estimate of when the MRCA of X lived". What does need emphasizing is that the MRCA of humans alive today may not have been the same individual as the MRCA of humans alive when (say) The Descent of Man and Selection in Relation to Sex was first published. Also some clarification about things like whether both parents of two siblings are regarded as the MRCA, or whether it is the younger of the two.Peak 16:38, 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)

The article gives a definition in the very first sentence, and uses it consistently. I don't see a second definition, either explicitly or implicitly. Which sentence do you think is the source of confusion? Peak 22:08, 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)

[edit] Time estimates

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 number of years between generations;
  • the percentage of couples who were childless;
  • the percentage of children who died before puberty; and
  • the percentage of relatives (however distant) who married each other. AnonUser 03:47, 29 November 2005 (UTC)

The "historical times" estimate is patently ridiculous, imho; it seems they used some sort of diffusion to model human migration. The statement

The actual MRCA is farther back if one attempts to take into account long-isolated peoples, such as historical tribes in central Africa, Australia and remote islands in the South Pacific.

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)

Now it does not: see Jewish calendar#Epoch or Ussher-Lightfoot Calendar#Ussher.27s history of the Earth, both of which suggest a date earlier than 3000 BC. --Henrygb 19:46, 11 March 2006 (UTC)
bad math on my part- however, i see from the ussher-lightfoot calendar that the time estimate DOES encompass the time of the 'great flood,' which may deserve suspicion. Zmbe 07:18, 12 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.

i don't think the idea is that every person has one gene per ancestor. you might want to check your source on that one. anyway, please add your id and timestamp to all entries- it's easy to do by typing four tilda's ~ in a row after your entry.Zmbe 06:31, 3 August 2006 (UTC)
Well, arguably you don't know that your inherited Y-chromosome DNA (if you're male) and your mitochondrial DNA exceed the contribution of other genes. Other genes are subject to recombination, sure, but since the ancestral populations were incredibly small in some cases, most of our recombining DNA could be from a very small group of people. --Saforrest 06:25, 29 November 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."

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)

[edit] MRCA of different species

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)

As I recall from the book, the point was that they exterminated all the "pure-blooded" ones. Presumably there are a few descendants still alive (as there are of the Beothuks, a similar sad story), but of course people of such recent mixed heritage would not preserve the 13,000-year genetic separation necessary to retain the MRCA figure. --Saforrest 06:03, 29 November 2006 (UTC)

[edit] Descendents of Edward IV and Henry VII

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

I know this is a very late reply, but for the benefit of anyone else who should happen to read through this page I would like to point out that due to exponential population growth, the majority (or at least a very significant proportion) of humans who have ever lived are still alive today. Some towns may have had many more past residents than present ones, but on the other hand many towns were founded very recently and thus have few past residents. Robin S 03:03, 13 June 2007 (UTC)

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

If I understand you correctly, you're saying it's okay to breed with "relatives" because there must exist copies of them on this faraway planet to whom you are unrelated. First off, no, it's not at all clear that it's an infinite universe. Second, even if such a doppleganger species did exist, what does that matter, since we are probably millions of years apart? Anybody you could conceivably want to breed with is still related to you.
Lastly, if one uses this "infinite universe" argument in the manner you've described, one could just as easily argue that there must exist a person who's identical to your mother or father. Therefore, incest is justified since an "unrelated copy" exists.
Sorry if that came across as excessively harsh. It's an interesting thought experiment. --Saforrest 06:00, 29 November 2006 (UTC)

[edit] Double meaning

"This simple calculation does not take into account the fact that every marriage is really a marriage between distant cousins which include second cousins, fourth cousins, sixteenth cousins and so on. The ancestry tree is not really a tree, but a graph. One can place all living people at the bottom of the graph and ancestors above their descendants. As each generation of ancestor is added at the top of the graph, 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 of the graph."

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)

I modified this paragraph to make it more clear. The MRCA was only one of many top-level, contemporary ancestors. The MRCA is not the only 'node' at the top of a 'tree'. The MRCA is one of many top-level 'nodes' of a 'graph'. Notice that the subsequent paragraph makes this even more clear; it describes how contemporaries of the MRCA also pass down their genes onto descendents. Fred Hsu 16:09, 19 February 2007 (UTC)

[edit] Generations

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)

I had a feeling someone would bring that up. It is true that exponential growth fails as a model if taken indefinitely since, as mentioned, over 80 generations one would expect over a trillion trillion ancestors. However, expecting the number of ancestors over 20 generations to be of a significantly lower order of magnitude than the 27 000 (<215) or so genes in the human genome seems to me to be unreasonable. For a start, wouldn't inbreeding pose a significant problem? Robin S 18:33, 21 March 2007 (UTC)

[edit] Are blood-type-B human more closely related to type-B chimp than to type-O human?

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:

Evolution of Primate ABO Blood Group Genes and Their Homologous Genes1, Mol. Biol. Evol. 14(4):399411. 1997

Comparison of allele O sequences of the human and non-human primate ABO system. (Abstract-only), Immunogenetics. 1999 Jun;49(6):517-26.

Perhaps I need to get this book?

Can someone shed more light on this topic? Fred Hsu 23:33, 1 June 2007 (UTC)

First, genetics dictate that the following combinations of phenotypes are possible in a species: A and O or B and O or AB, A, B and O (this assumes that IA, IB and IO are the only possible alleles). However, beyond that there is no reason to suppose that all IB alleles (for instance) in different species are homologous. As I understand it, IB alleles arose as a point mutation in IA alleles, while IO alleles arose as a frame-shift mutation. There is no reason why such mutations could not occur multiple times in evolutionary history, even within the history of a single species. On the other hand, the fact that an IB allele is present in two different species does not indicate that the two incidences of the allele are not homologous. If chimps lack an IB allele in their populations, that could mean that it evolved independently in humans and other primates, or that it went extinct in chimps and the remainder of primates (though the latter seems less likely). Robin S 02:55, 13 June 2007 (UTC)
Right. This is consistent with what I found during my short research. So, I guess you are saying that I can't use this as a definite example of trans-specific polymorphism in the article, because we don't yet know the answer. Sigh. Fred Hsu 01:06, 14 June 2007 (UTC)
Ah, discussion on RichardDawkins.net generated more data points. Here is another paper:
Gene Diversity of Chimpanzee ABO Blood Group Genes Elucidated from Intron 6 Sequences
The paper doesn't specifically talk about trans-specific polymorphism. It is about estimates of nucleotide diversities in chimps and bonobos. But the chart on the second page seems to indicate that human ABO alleles are quite far apart from other apes in terms of nucleotide differences in intron 6 sequences. Fred Hsu 02:55, 9 November 2007 (UTC)

[edit] Nominated most ancient common ancestor for deletion

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)

Why do you want o merge Last Common Ancestor into this article? They are clearly differently as you pointed out. And you split Identical ancestors point which I fully support. Why not create a new section in this article to talk about Last Common Ancestor, the same way it now talks about Identical Ancestors Point? Fred Hsu 21:55, 23 July 2007 (UTC)
Also note that Dawkins uses the term concestor to indicate the MRCA of a set of species in order to avoid confusing people. Perhaps this is what Last Common Ancestor attempts to describe... Search for concestor in this article. Fred Hsu 22:08, 23 July 2007 (UTC)
I just enhanced MRCA article to clarify relationship among MRCA, LCA and concestor. If there isn't a lot of extra material for LCA, then perhaps we can merge it into MRCA as you suggested. If we decide to leave them as separate articles, then we should probably redirect concestor to LCA instead of MRCA. Fred Hsu 03:44, 24 July 2007 (UTC)

[edit] Gene ancestry: question about tree vs. graph

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)

Please check out the first chapter 'Digital River' and (especially) the second chapter 'All Africa and her Progenies' of the article River out of Eden. These answer your question specifically. The short answer is: there are two types of ancestry chain/tree/graph you can draw. You can draw one from an organism's perspective, and you can draw another one from gene's perspective. The organism ancestry and pedigree are graphs. Genes have a single chain of ancestors and a tree of descendants. Fred Hsu (talk) 14:09, 18 November 2007 (UTC)

[edit] Changes by Lklundin on MRCA being a set of people

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)

Thanks for the constructive comments on my changes. At first I intended to make only some language changes, and then as an afterthought I realized that the MRCA need not be unique (it is obvious when one thinks about it, e.g. the mate/spouse of a MRCA is a likely 2nd MRCA, even though there can easily be many others). Since this was additionally my first edit on this article, I can understand why the change was not accepted in its entirety, and I think it would have been better to open this issue up for discussion first. Now that a discussion has been opened I would like to make a few points based on (the abstract of) J.T.Changs well-cited article: "Recent common ancestors of all present-day individuals":
1) While each of the patrilineal and the matrilineal MRCA is unique, the both-parent MRCA need not be unique.
2) "most recent" is defined in terms of generations, not years.
3) For a given population of size n, the number of generations, Tn, back to a MRCA has a distribution that is concentrated around log2(n), where log2 is the base 2 logarithm. In contrast, the expected number of generations back to one of the patrilineal and the matrilineal MRCAs is 2n (with a standard deviation of n).
4) Further: with high probability for large n, in each generation at least X log2(n) generations before the present, where X is some positive constant, all individuals who have any descendants among the present-day individuals are actually ancestors of all present-day individuals.
My opinion about my above points:
The article could be improved by clearly stating some non-statistical properties of the MRCA, i.e. that
A) 'most recent' is in terms of generations,
B) MRCA need not be unique
C) each individual in the population that coexisted with the MRCA(s) falls into one of three groups:
C1) Those who have no living descendents, and the remaining:
C2) ancestors of a subset of the current population, and
C3) people who are also ancestors of the entire current population, which would include any parents and grand-parents of the MRCA(s).
- and I think it is worth mentioning the following statistical property of the MRCA(s):
the age (in terms of generations) of the MRCA depends on the logarithm of the population size (which explains why the MRCA is estimated to have lived so much more recent than each of the patrilineal and matrilineal MRCA).
Finally, I also think it is worth mentioning that by going a certain number of generations further back, from that point and back the probability that group C2) is empty is high.
Lklundin (talk) 22:02, 28 November 2007 (UTC)
Great ideas and data. Perhaps a new section is needed for these. The concept of MRCA and its implications are complicated enough that many people already find it hard to understand. I believe we should try not to make existing sections more complicated than they already are, in an attempt to put forth all available information. A separate section to elaborate on points you raised here, perhaps after 2.4 Time estimates, will be more useful. Fred Hsu (talk) 00:45, 29 November 2007 (UTC)
By the way, are you familiar with "last common ancestor"? Can you comment on the issues I raised on Talk:Last_Common_Ancestor? Can you check out sections, 2, 3, 4 and 5 please? The original article before I pruned it can be found here. Thanks. Fred Hsu (talk) 00:45, 29 November 2007 (UTC)

[edit] notable coancestors

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)

You mean, something like the complete table of all concestors in the The Ancestor's Tale? Fred Hsu (talk) 23:04, 12 December 2007 (UTC)
I just just made this change to the article. Fred Hsu (talk) 23:09, 12 December 2007 (UTC)