Talk:Identical ancestors point

ancestors to IAP

Perhaps should note that as we move back from the IAP the number of individuals (within the species) gets smaller and smaller until eventually there is only one. This would be the Last common ancestor (see Wikipedia). Depending on whether Multiregional or Recent Replacement is correct, the date of the LCA of modern man is either 2 Million BCE or 40,000. The LCA does however, exist, and leads to the IAP. Tom Schmal 00:41, 2 November 2007 (UTC)

Your understanding of the LCA is incorrect. LCA is basically the same as MRCA, except that nowadays MRCA is used more often than not to define most recent common ancestor among a species (that is, common ancestor of a set of people), while LCA is used to define most recent common ancestor of a set of species. You can think of LCA as what Dawkins calls 'concestor'. Notice that both LCA and MRCA only make sense when applied to a 'set' of organisms. Pay attention to the words 'most recent' and 'common'. See Most_recent_common_ancestor#MRCA_of_different_species. Fred Hsu 02:24, 2 November 2007 (UTC)

What you are trying to describe is the original individual whose gene undergoes a mutation which eventually become universal in an entire population later. This individual has contemporaries. Think about it, how would a single individual mate? Fred Hsu 02:24, 2 November 2007 (UTC)

Page restored

Cool. I guess this will make it clear to people that identical ancestors point is NOT the same as MRCA. Fred Hsu 14:16, 23 July 2007 (UTC)

I think the Exact Identical ancestor points listed in this article are questionable. (by anonymous editor)

removed the caveat section

I removed this:

It should be noted that the 'identical ancestors point' is dependent upon the single recent origin hypothesis. Should humans have evolved from multiple sources and then merged, the concept cannot be correct. It should be noted that some species today (i.e. birds) have merged (also called species integration; thus it is possible for humans, as well, to have come from multiple origins. See the multiregional hypothesis for the alternate view.

Please cite references for merging of bird species. Also, I think such arguments should be added to most recent common ancestor. Notice that Mitochondrial Eve article already discusses this topic.

I am nominating the species integration for deletion (see its talk page). Thus I don't believe this paragraph is appropriate at this time in this articl. Fred Hsu 23:20, 4 August 2007 (UTC)

Even if the 'word phrase' is eliminated, the concept of 'multiple origins' is the basis of the multi-regional hypothesis. Given that the 'identical ancestors point' is contingent upon ideas widely perceived to be 'true' but which remain UNPROVEN, I find room to insert a 'caveat' into the article. Indeed, it was questions about the 'wobbling' of planets that led to the discovery of Pluto. However, it turned out that the 'wobbling' was an errant calculation--but fixing this calculation helped validate the theory of relativity. Questioning loopholes in scientific theory is an integral part of ensuring that we have the 'right answers', rather than simply being 'in the ballpark.'Ryoung122 09:48, 7 August 2007 (UTC)

If my understanding of multiregional hypothesis is correct, this theory does not claim that modern human was a result of merging of multiple non-breeding species. Instead, the theory states that basically the various descendant groups of Homo erectus (including Neanderthal) are all one interbreeding species. It states that all these groups (one species) evolved around the world into Homo sapiens sapiens via frequent breeding around borders of regions. If so, the calculation for MCRA and identical ancestors point is still perfectly valid for the multiregional hypothesis, as all such hominids are one single happy breeding species. Fred Hsu 16:22, 7 August 2007 (UTC)

Dawkins provides a diagram for the multiregional theory in The Ancestor's Tale, based on Alan Templeton. The multiregional theory postulates "Out of Africal again and again", three waves of African exodus, the earliest being Erectus about 1.7 million years ago.Skates61 (talk) 05:01, 16 February 2009 (UTC)

Versus MRCA

The information held on Identical Ancestor Point appears to be questionable. .14:28, 17 August 2007 (UTC) 86.147.2.137 14:41, 17 August 2007 (UTC)

You are probably thinking about matrilineal MRCA. Please see explanation at Mitochondrial Eve. I'll add a few words to this article as well to clarify this. No, it's not an error. Fred Hsu 02:10, 18 August 2007 (UTC)

I don't get it.

I don't get it.

Is IAP a theory, a statistical probability or is it a mathematically proven fact (like mitochondrial eve)? Is it a DNA inference, a population theory or is it an obvious fact that I do not see?

Let's imagine that some geographical or continental isolation event happened at the estimated time of the IAP dividing the population. Two siblings were thus separated. The parents and entire lineage of these two individuals may obviously have a probability of being a common ancestor. But what is it that makes all their contemporaries as either with terminated line of descent or a common ancestor to BOTH populations?

I don't get it.

The article seems to give the arguement that as you go back, a bigger and bigger percentage of the population will be implicated, but why can't this be a converging trend?

What observable evidence is it that would separate these two scenarios?

I feel stupid for asking this, so bear with me. —Preceding unsigned comment added by 195.139.24.169 (talk) 12:35, 18 April 2008 (UTC)

It looks a reasonable question to me. The answer is that for the statement in the article "The identical ancestors point for Homo sapiens has been estimated to between 15,000 and 5,000 years ago", the figure has been crudely modelled as in the reference. My guess is that this figure could be way out. On the other hand, I am sure there are strong statistical arguments that show the probability of there not having been an identical ancestors point some time in the last 500,000 years is insignifcantly small. --Rumping (talk) 07:54, 20 June 2008 (UTC)

It does seem that the article should answer the above questions "Is IAP a theory, a statistical probability or is it a mathematically proven fact (like mitochondrial eve)? Is it a DNA inference, a population theory or is it an obvious fact that I do not see?" Cmadler (talk) 01:49, 27 August 2008 (UTC)

The IAP is fact, because the population is finite. The time to IAP is what is open to discussion. Because there are no longer any isolated human populations, it is resonable to conclude a fairly recent MRCA. In a random population the time to IAP is 1.77 times the time to MRCA. But, if a sub-population was in complete isolation, then the time to IAP is necessarily before the time of isolation, because during the time of isolation the sub-population will have different ancestors than the main population. The time to MRCA remains recent, however, because no population is in isolation now (we can all trace to the MRCA thru at least one line). Note that if we had considered "the population" to be everyone living in 1491, then the MRCA would also be considerably further back in time, because in 1491, for example, Tasmanians had been living in isolation for ~10,000 years, sharing no common ancestors with anyone anywhere else during that timespan.Skates61 (talk) 05:32, 16 February 2009 (UTC)

• It doesn't add up to me. I'm sure there is always someone alive who did not reproduce, therefore there can never be a point where everyone alive is an ancestor to someone alive today. Kenallen (talk) 02:57, 14 March 2009 (UTC)

Kenallen, you are correct in that not everyone reproduces, but you missed part of the definition of IAP. At the IAP, everyone falls into one of two categories: either they are the ancestors of everyone alive now, or, they are the ancestors of no one alive now. Similarly, someday in the future, each person alive today will either be 1) the ancestors of everyone alive at that future date or 2) the ancestors of no one alive at that future date.Skates61 (talk) 04:47, 11 June 2010 (UTC)

Everyone alive today shares the same set of ancestors if you go before that point. This set of ancestors only includes those who reproduced. At the human identical ancestors point, our ancestors lived in four to six continents (Africa, Asia, Australia, and Europe; possibly Americas). —Preceding unsigned comment added by 98.208.56.181 (talk) 06:12, 7 July 2009 (UTC)

Because there are no longer any isolated human populations, it is resonable to conclude a fairly recent MRCA.

The time to MRCA remains recent, however, because no population is in isolation now (we can all trace to the MRCA thru at least one line).

So you are claiming that the article Uncontacted peoples is erroneous? Especially keeping in mind the Sentinelese people. --Florian Blaschke (talk) 19:41, 17 January 2011 (UTC)

Does this mean that at the IAP there were two groups of people: One group of people who left no descendants alive today, and one group of which every member was the ancestor of everybody alive today? — Preceding unsigned comment added by Deathmare (talk • contribs) 16:16, 6 June 2011 (UTC)

Yes. That is the definition of IAP. To all who posted questions in this section, I recommend Dawkins' River Out of Eden, cited in the article. It provides detailed explanation and examples. Fred Hsu (talk) 12:17, 7 June 2011 (UTC)

What this article needs now

1. Some simple examples of what is being discussed (such as given in last common ancestor)

2. A diagram or two

3. Rewriting for style and clarity.

I would give this last a go now, but I'm a bit hazy on some of the details. If no one has done it in a couple of weeks, I will attempt it. Myles325a (talk) 04:02, 10 May 2008 (UTC)

Dates suggested make no sense

This article describes a concept of a common ancestor living 5,000 to 15,000 years ago. However, it's reasonably documented that one fork of humanity moved to the Americas at least 10,000 years ago, and to Australia closer to 50,000 years ago, and as long as pureblood native americans and australians exist, a common ancestor dated after those forkings is not possible.

Is this article the result of speculation or (bogus) original research?--Bradtem (talk) 21:26, 13 July 2009 (UTC)

Identical ancestors point is derived from most recent common ancestor (MRCA) which is statistically derived. Most people reject MRCA at face value by incorrectly assuming that the MRCA passed all his/her genes to all people today. In fact, the MRCA may not have passed one single gene to anyone living today. See the Time Estimates section on MRCA to answers to your question. Fred Hsu (talk) 04:59, 17 July 2009 (UTC)

Of course, if there is a group of pureblood natives which has never mixed with people from other continents directly or indirectly via population diffusion, yes the time estimates for MRCA and identical ancestors point will need to be drastically modified. Fred Hsu (talk) 04:59, 17 July 2009 (UTC)

If they got to Australia, a few diffused got back. There was never a land bridge to Australia. The same technology that got them there let them go back, unless they "forgot" it, but that seems unlikely. For America, the Inuit were sea faring, for Australia, the Torres straight islanders were. Note that this diffusion is very little, but all it takes is one ancestor to leave. By the way, Australia say multiple population invasions. — Preceding unsigned comment added by 98.208.56.181 (talk) 05:55, 19 August 2009 (UTC)

The recent date applies to today, 500 years after the age of exploration. The point is that there are no isolated populations today, and there has been ample time, five centuries, for diffusion even to the most remote populations. It may be argued that there remain a couple of hundred uncontacted peoples who may screw up this estimate, but it is difficult to know unless they are, you know, contacted first. It goes without saying that the iap estimate for times in the remote past, say around 3000 BC was much higher than it is today. In 3000 BC, the iap may in fact have lain several tens of thousands of years in the past.

That said, I do find the low estimate of 5,000 years unreasonably low. It is important to point out that (a) the estimate is just based on a simulation model and (b) the authors of the 2005 paper themselves stated they found the figure surprisingly low. It would be interesting to know if there have been any other estimates since 2005. As the article correctly points out, even if it turns out that the iap is at about 10,000 BP, meaning that every person alive today is descended from, say, the population of New Guinea at the time, this would still mean that most people have inherited zero base pairs from these ancestors, as a marginal contribution to your family tree is completely bred out after about 800 to 1,000 years. --dab (𒁳) 11:24, 15 May 2010 (UTC)

As I pointed out above, there are still uncontacted tribes all over the world, such as the Sentinelese, and therefore the assertion "there are no isolated populations today" seems to be simply wrong. While it is obviously impossible for practical reasons to conclusively prove (for the time being) that the Sentinelese have seen no admixture, the assumption is plausible: There is no evidence for genetic admixture from mainland groups in other Andamanese groups, either (which does not preclude cultural contact, to address an objection on Talk:Andamanese people, but that is immaterial here), and there is no reason to think that the Sentinelese of all Andamanese groups form the big exception. The Andamanese have been isolated for millennia, possibly tens of millennia, as the genetic evidence strongly suggests. --Florian Blaschke (talk) 13:48, 29 October 2013 (UTC)

Denisova hominin and IPA of modern Humans

The recent evidence on the Denisova hominin suggests that the IAP of modern Homo sapiens dates back much more than 15,000 years. According to estimations, the time of divergence between the lineage leading to modern Humans and that leading to Denisovans is roughly 800,000 years ago. Much later, there must have been occasional interbreeding between the two lineages, somewhere in Asia, because the genome of modern Melanesians derives partly (between 4% and 6%) from Denisovans. However, this gene flow obviously did not spread into other modern humans, as their genome contains no traces of Denisovan ancestry. This suggests that the IAP of modern Humans (including modern Melanesians) is at least 800,000 years ago. Is my reasoning correct? 87.180.111.59 (talk) 09:51, 5 January 2011 (UTC)

references

http://www.nytimes.com/2010/12/23/science/23ancestor.html?_r=1&hp

hominin vs. other animals

The article speaks about hominin and other animals. The hominin part ist problematic.

That a IPA - found by a simulation or a pure mathematical model - can be realty has one precondition: all animals must mate together. Obviously: when populations are seperated over X a. they can't have the same ansestor <X a. Since some populations - for ex. the Onge of the Andaman Islands - are isolated for prox. 40 - 50 ma. the simutation model will not help, to find the time of the real MRCA or IAP. --Sophia Nabokov (talk) 09:49, 14 January 2011 (UTC)

Before leaving Africa?

Must not this point be some time before the ancestors of non-Africans left Africa? --Oddeivind (talk) 21:18, 21 July 2012 (UTC)

Religious Fallacy at sight: WATCH OUT

This 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. — Preceding unsigned comment added by Cohelet (talk • contribs) 20:41, 19 March 2013 (UTC)

Cohelet -- regardless of what the effects of the Toba volcano may have been, it seems quite likely that multiple episodes of human evolutionary change took place within relatively small populations (since it's easier for a mutation to establish itself in a small population than in a large population etc.). The transition from 48 chromosomes to 46 likely took place within a relatively small population. A species having a relatively small population for number of generations means that the identical ancestor point is not too far back. Also, if the living members of a "species" don't have identical ancestors until several branchings up on the tree of species differentiation, then it's not likely to be a valid species at all.

The fact that humans have less genetic diversity overall than chimpanzees, despite having a vastly greater population, points in the same direction. This article is founded on sometimes-surprising mathematics (ask the king in the rice and chess story about the unintuitive properties of exponential numbers!), not religious fundamentalism. AnonMoos (talk) 08:03, 20 April 2013 (UTC)

The (real and scientific) fact that population 'bottlenecks' had occurred to Sapiens and pre-Sapiens species mean that at this point there was a lot of Common ancestors, extraordinarily; but there's no mathematical, genetical or what is worse logical proof to say that, once they begin to spread, their 'sons' were 'fathers' of all the mankind alive today OR their lineage was extinguished. The only LOGICAL thing is that they were fathers of 'some' of the diferent lines of living people. Being VERY, childish, schematic, from the 'population bottleneck' one cousin is the father of europeans, other of (native) americans, other of aborigene, other of oriental and so on: through history their 'grandsons' merge again and again, and again, but there were some that DIDN'T during thousand and thousand years like amazonian, aborigene and other isolated populations. So, you can ALWAYS find one of the 'cousins' in the bottleneck that is ancestor of SOME of the humans today but not of them all. Proposing a time of 5-15 thousand years is merely a joke having in mind that the humans move to America around 25-40K years ago, being and isolated branch since. To that date you must add the time they were moving through Asia, maybe other 40-50K years; then you have that the african-european population was genetically isolated from americans at least for 50K years, making imposible any set of common ancestors earlier than that, and pure nonsense all of the proposed in this article. Cohelet. — Preceding unsigned comment added by Cohelet (talk • contribs) 19:17, 3 June 2013 (UTC)

Definition meaningless?

If we look at the nature article, it says "Besides dating our most recent common ancestor, Rohde's team also calculates that in 5,400 BC everyone alive was either an ancestor of all of humanity, or of nobody alive today. The researchers call this the 'identical ancestors' point: the time before which all the family trees of people today are composed of exactly the same individuals."

If we focus on the first sentence and take this as the definition of the "identical ancestor's point", then surely the definition of it being a specific momentary time in the past is meaningless? Is it not possible that we could go forward in time to say 5000 BC and that everyone alive then were either an ancestor of all of humanity, or of nobody alive today? Both sets of people would have had children and though some lineages may have died out in 400 years, you would still have descendants of both lineages. Of course, we could keep going forward in time till we reach a point in time when the last lineage, of one of the people alive at the IPA time but who did not have children with anyone who was in the lineage that was ancestral to all of humanity alive today, dies. Just before that point everyone alive was either an ancestor of all of humanity, or an ancestor of nobody alive today- i.e this last lineage person who's just about to die without reproducing. Just after that death, everyone alive is only ancestral to all of humanity. Surely then the definition in the first sentence above defines a range, whatever name you wish to call that range?

But hang on- surely you can go back in time beyond the "IPA" and it can still be the case whereby you have a situation where everyone alive was either an ancestor of all of humanity, or of nobody alive today- both groups of people can't just pop out of nowhere (of course that is till we go back to the LCA, but that's irrelevant in this discussion), they both had to have had parents. Unless they are talking about the most recent common ancestor of both of these groups of people- but then surely, that would be exactly the same person as the MRCA of all of humanity alive today? ...Unless, they are talking about a point in time where they population is split equally into two groups, 50% of everyone alive being an ancestor of all of humanity, and 50% of everyone alive being an ancestor of nobody alive today. But then surely, this could happen more than once in humanity's history, surely, it could even stay like that for a period? It's not as if the lineage that sired all of humanity alive today grew at a constant rate and that the lineage that did not shrank at a constant rate, is it? There can be bottlenecks in population for both groups of people, or a "bottleneck" can stay at the same width for some time.

And onto the second sentence in the quote above: "the time before which all the family trees of people today are composed of exactly the same individuals" or in the actual paper's words "The point beyond which everyone alive today shares the same set of ancestors". I honestly don't see how this isn't just the MRCA; consequentially I don't see how it could be further back in time than that TMRCA

Either definition, the one in the first sentence and the one in the second, is meaningless, or I'm missing something. What on earth are they trying to convey? — Preceding unsigned comment added by 77.96.64.133 (talk) 20:28, 8 March 2014 (UTC)

These points are defined with respect to the population alive at a given time, and can change when the population changes (through births and deaths). Otherwise, I'm not too sure what you're asking. It means that people have the same set of remote ancestors, not necessarily that they have the same individuals in exactly the same genealogical position ins their lineages... AnonMoos (talk) 01:38, 21 March 2014 (UTC)

Calling shenanigans on the dates

It sounds like this estimate is based on some mathematical model with little relevance to reality. The simplifying assumptions of this model should really be clarified. As far as reality goes, people above have raised north america and australia as objections.

There is a counterargument above about the plausibility of a pureblood native american, but I'll point out that even if there aren't any, that's not good enough. It has to go the other way too, that is to say, it would also be refuted by anyone who doesn't have any native american ancestry. Are you telling me that, for example, every australian aborigine has native american ancestry? 500 years doesn't seem long enough to make this happen.

And this is not to mention other isolated groups. --God made the integers (talk) 04:27, 10 January 2017 (UTC)

It would NOT be required that Aborigines have North American ancestry. Both could have Asian ancestry at the relevant time. AnonMoos (talk)

That is sufficient for MRCA, but I'm talking about this:

• The identical ancestors point for Homo sapiens has been the subject of debate. Some mathematical models yield surprisingly recent dates, a mere few thousand years ago.[3][dubious – discuss]

We're talking about IAP, not MRCA. The estimate given is vague but definitely post-isolation and pre-contact. By definition, if anyone alive today has ancestry from a group that was isolated at the IAP, then everyone does. The conclusion follows. --God made the integers (talk) 20:56, 10 January 2017 (UTC)

You obscured your meaning by mentioning 500 years, since no-one realistically believes that the current Identical ancestors point is 1517 AD, and there's no mention of such on the article. But I now see that you were referring to previous talk page discussions above, not to the article itself... AnonMoos (talk) 10:50, 11 January 2017 (UTC)

No what I'm talking about is what I just quoted, which was taken from the article. 500 years ago refers to the time of contact. The time of isolation was more than ten thousand years ago. If we assume that the IAP falls anywhere between them, which "a mere few thousand years ago" would, it follows that every person alive is descended from at least one person alive in north america at the time of contact. --God made the integers (talk) 20:24, 11 January 2017 (UTC)

I'm still not too sure how 500 years comes into it -- meaningful European contact with Australians was significantly more recent than 500 years ago, but Australians were not strictly isolated before that time: there was interchange with Makassans in west Australia, and interchange indirectly with New Guinea through the Torres Straits Islanders in northeast Australia. AnonMoos (talk) 03:26, 12 January 2017 (UTC)

500 years refers to north american contact, not australian contact. If every person alive today has a north american ancestor from 500 years ago, then it follows that every australian aborigine alive today has a north american ancestor from 500 years ago. I am sorry for the confusion, I hope I have finally made myself clear. --God made the integers (talk) 18:25, 12 January 2017 (UTC)

But now you seem to be discussing MRCA, while earlier you said you were discussing IAP, not MRCA. NO INFORMED PERSON believes that the IAP was 500 years ago, so I really don't see how 500 years is relevant to the IAP. If you have reservations about material in the article, then I really wish you would discuss what is actually in the article, and not just allude to previous talk-page discussions. AnonMoos (talk) 03:02, 13 January 2017 (UTC)

Argh :-) No, I did not mean anyone thinks the IAP is 500 years ago. 500 years ago refers to contact, as I say. I was not saying anything about MRCA either. I am talking about whether the IAP really is a few thousand years ago, as in the sentence from the article I quoted.

Why is contact relevant to IAP, you ask? Because lines of descent remain within an isolated group! Generally, if a group (that is extant today) was isolated at the IAP, then, from the definition of IAP, certain things follow about our ancestry at the (later) time of contact with that group.

That is why I keep going on about native american ancestors from 500 years ago. Not because anyone estimates the IAP or MRCA or anything at 500 years, but because it seems to follow from the article's estimate of IAP of a few thousand years ago. That is what I'm getting at. I could have been clearer. --God made the integers (talk) 07:24, 13 January 2017 (UTC)

• Okay so. Looking at Rohde 2003: models A and B are "intentionally abstract and bear little resemblance to the real world." Model C tries to be more realisitic. But it does have late back-migration across the Bering strait. Different versions of the model have different results. From figure 10, we have estimates of ACA point ("All common ancestors" point, another name for IAP) from as late (C1) as about 4000 years ago to as early (C3) as 15000 years ago. The "moderate" (C2) estimate is about 7500 years. As I read figures 9 and 10, C1 assumes an average of 100 people per generation have been crossing the Bering strait in each direction since 12000 years ago. C2 assumes 10 people per generation, C3 assumes 1 person per generation. --God made the integers (talk) 18:29, 13 January 2017 (UTC)

The Americas were hardly isolated for 10,000 years until 500 years ago. There were at least 3 major waves of migration (the "Amerind", Na-Dene, and Inuit-Aleut), the western Inuits continued to go back and forth across the Bering Strait from time to time for a long time, and it's hard to understand how the sweet-potato got across the Pacific without a few Polynesian boats arriving on the shores of Central America or northern South America. Ultimately, as far as I can understand your objections (which was not at all easy to do at first), they seem to be based wholly on your intuitive perceptions that the results of scientific studies are counterintuitive. But merely appearing counterintuitive is no refutation by itself. AnonMoos (talk) 19:04, 15 January 2017 (UTC)

Naming

The concept is sound, and I don't doubt that it appears in Dawkins 1995, but I suspect the name doesn't. And the Rohde (2003) paper (from which the doubted estimate above) is quoted in the article:

• The point beyond which everyone alive today shares the same set of ancestors is somewhat harder to predict, but...

Which doesn't use the name "identical ancestors point". Now, I can't think what else "identical ancestors point" could possibly mean, so I'm not going to place whine-tags all over the article, but it would still be nice to have some source for the name. --God made the integers (talk) 21:20, 10 January 2017 (UTC)

Did you see the external link http://www.nature.com/news/2004/040929/full/news040927-10.html ? -- AnonMoos (talk) 10:50, 11 January 2017 (UTC)

No I hadn't, thanks. --God made the integers (talk) 20:30, 11 January 2017 (UTC)

Dating of IAP and neanderthals

Estimates that put the IAP for modern humans very recent (like a few thousand years ago) confuses me. For example, if there are any Native Americans alive with ancestors who lived in America 5000 years ago, which I think it is safe to assume that it does, then if these estimates are correct then everybody on earth would have to have an ancestor that lived in America 5000 years ago. Every European and every African (notice the difference between this and MRCA). Surely this can hardly be the case. I find estimates at 15 000 years to be easier to swallow, but that brings me to another question. I have red that all humans from outside of Africa have some Neanderthal ancestry, but not sub-saharan Africans. I don't know if that is true (genetic similarities could be explained by common ancestors rather than direct descent), but since the Neanderthals disappeared well before 15 000 BC either everyone on earth has neanderthal ancestry or nobody does, if the IAP estimate is correct. Does anybody know anything about this? — Preceding unsigned comment added by 84.55.118.131 (talk) 15:17, 17 November 2017 (UTC)

>>> Read the paper by Rohde, Olson and Chang. All populations have intrusions from neighboring ones. It is increasingly clear that multiple waves of East Asians settled the Americas; in the borderlands near where Ms Palin sees Russia, there have almost certainly been small, occasional numbers of people going both ways from time to time. Hence, Native Americans bloodlines get intrusions from Asians, who themselves have intrusions from Europeans, middle easterners, south Asians and so on.

Re Neanderthals, non-Africans have a 1-4% *genetic* component. Because Neanderthals are way before the IAP, Africans have Neanderthal Ancestry too. But it would be in tiny proportion compared to what Eurasians would have. If Jane was a Neanderthal with descendants living today, she may be represented x million times in the pedigree of a typical Euro, if we could know pedigrees that far back, but only a relative handful of times in the pedigree of an African. Keep in mind too that for everyone, the number of genealogical ancestors is vastly superior to the number of genetic ancestors. Even most of your 8th great grandparents are NOT your genetic ancestors, just a random few escape the recombinatorial winnowing. Skates61 (talk) 00:52, 27 April 2018 (UTC)

>>> Thank you for your answer. I don't think it is necessarily true that the number of (identical) genealogical ancestors is vastly superior to the number of genetic ancestors, we are all pretty inbred if you a thousand years back. And if most of your great-grandparents are not your genetic ancestors, you would have inherited your entire genome from just three of your great-grandparents. I don't think that seems very likely. People who are mixed-race with 1/4 of one thing and 3/4 of something else usually have some characteristics from the 1/4 people group. I don't think all of that DNA is lost in just one generation. Do you have any sources that show that sub-saharan africans have neanderthal-DNA? I agree that since the neanderthals died out several tens of thousans of years ago, that is enough time to make it likely that the DNA has been spread south of Sahara through migration etc. But I've never seen studies to confirm it. — Preceding unsigned comment added by 84.55.118.131 (talk) 19:19, 7 June 2018 (UTC)

Point 2 “Essentially, this would make the IAP the point in the group's past where everyone is related” is incorrect

Everyone is related earlier, at the time of the MRCA, as they are all at least distant half cousins through the MRCA.

I plan to update this article shortly to correct this and get the definition back to what Chang, Rohde and Olson explained. The article is also currently suffering from a lack of sourcing, in particular we are beginning to see genetic studies backing up the earlier simulations work, I will cite one.

To all of you here who keep arguing for isolated populations, try to find one who has never mixed with their neighbors - it’s impossible. Even a tiny amount of mixing will introduce all the ancestry of the “mixee”, so to say, to the isolates. Skates61 (talk) 22:06, 26 April 2018 (UTC)

3,400 Years BP

Should we include a reference to Adam Rutherford's categorical statement that this point is only 3400 years ago. It's in his newly published book as reviewed but in the book he provides little in the way of back up. Nine-and-fifty swans (talk) 09:38, 8 February 2020 (UTC)

References