Talk:Neanderthal admixture theory

WP:SS Solution to Material Distribution in Articles

This is a quick WP:SS solution to the unsatisfactory distribution of material in the Neanderthal and Neanderthal extinction articles. The article can still be moved to a better title. Note that "Neanderthal admixture" takes the modern viewpoint, i.e. the search for Neanderthal DNA in modern humans, while "interbreeding" takes the Paleolithic viewpoing, i.e. the interbreeding during the Middle Paleolithic which resulted in the modern situation. Both are valid titles for discussing the same phenomenon. Possible fuller titles would be:

• Neanderthal interbreeding hypothesis
• Interbreeding of Homo sapiens and Neanderthals
• Interbreeding of Cro-Magnon and Neanderthals
• Neanderthal admixture in modern humans
• Neanderthal admixture in modern human DNA

--dab (𒁳) 10:39, 9 May 2010 (UTC)

Oh didn't see this, but just went ahead and moved it to the first proposed title. It doesn't take sides, and it is similar to the title of the extinction article. FunkMonk (talk) 16:33, 9 May 2010 (UTC)

Would "Neanderthal interbreeding" be better than "Homo sapien interbreeding"? --Millstoner (talk) 16:40, 9 May 2010 (UTC)

Now that I think of it, how about Neanderthal admixture hypothesis? That makes it less ambiguous. FunkMonk (talk) 16:42, 9 May 2010 (UTC)

Or how about just Humanderthal Hypothesis? ;) --Millstoner (talk) 13:38, 10 May 2010 (UTC)

an excellent idea! :o)

"Neanderthal admixture hypothesis" is perfectly fine, or it certainly "doesn't take sides", it just isn't fully explicit: "Neanderthal admixture [viz. to the modern Human genome, not to donkeys or gerbils] hypothesis". If we can live with the implication unstated in the title, I see no problem with this solution. --dab (𒁳) 15:18, 10 May 2010 (UTC)

I at least think it is pretty clear, should be a given that it refers to admixture in humans, and not something else. FunkMonk (talk) 16:02, 10 May 2010 (UTC)

You mean modern humans. People for some reason keep talking about "hominids" when referring to the Paleolithic. The Neanderthals were, of course, humans. Apparently not even a distinct human species, at best a subspecies, say, like wolves to dogs, or like a Przewalskii horse to any regular horse. --dab (𒁳) 21:20, 11 May 2010 (UTC)

Well, in the Wikipedia sense, no, Homo sapiens sapiens redirects to human, heh. And I've actually advocated for that article being split in the past, with a Homo sapiens article separated from the Homo sapiens sapiens article, but no one agrees. FunkMonk (talk) 22:32, 11 May 2010 (UTC)

Introduction is ambiguous

Neanderthals are either classified as a subspecies (or race) of humans (Homo sapiens neanderthalensis) or as a separate species (Homo neanderthalensis). The introduction to the article states, "the result of interbreeding of Neanderthals and Homo sapiens during the Middle Paleolithic". Since Neanderthals are sometimes classified as Homo sapiens, perhaps the intro needs to be modified for clarification. --Millstoner (talk) 16:10, 13 May 2010 (UTC)

This is correct. I was going to say "Neanderthals and Cro-Magnon", but that is open to doubt for different reasons, because Cro-Magnon is not even a taxonomically meaningful term, and refers to people in Europe, while the interbreeding appears to have taken place also in the Levant.

Perhaps "Neanderthals and anatomically modern humans" would be best. --dab (𒁳) 18:35, 13 May 2010 (UTC)

What about "Neanderthals and early modern humans"? --Millstoner (talk) 23:47, 14 May 2010 (UTC)

"early modern humans" is just a redirect, and I am not sure it is a common term. In my book, "early modern humans" are people who were alive between AD 1500 and 1770. --dab (𒁳) 10:39, 15 May 2010 (UTC)

Max Planck Institute press release

Analysis of the Neandertal genome indicates that, contrary to previous beliefs, humans and Neandertals interbred: The Neandertal in us --Millstoner (talk) 14:47, 16 May 2010 (UTC)

The current version states "An analysis of a first draft of the Neanderthal genome released in May 2010 indicates that interbreeding did occur"

I believe the results are still too preliminary to be treated as hard facts. Most of the study was based on the analysis of just 5 individuals (a San, Yoruban, French, Han and Papuan). We don't know if the same results would hold up if more modern humans were analyzed or if more Neanderthal samples were analyzed. The authors also offer an alternative explanation when they state

Although gene flow from Neandertals into modern humans when they first left sub-Saharan Africa seems to be the most parsimonious model compatible with the current data, other scenarios are also possible. For example, we cannot currently rule out a scenario in which the ancestral population of present-day non-Africans was more closely related to Neandertals than the ancestral population of present-day Africans due to ancient substructure within Africa (Fig. 6). If after the divergence of Neandertals there was incomplete genetic homogenization between what were to become the ancestors of non-Africans and Africans, present-day non-Africans would be more closely related to Neandertals than are Africans. In fact, old population substructure in Africa has been suggested based on genetic (81) as well as paleontological data

In addition, some archeologists have criticized this study as not taking into account the archeological record which tends not to support interbreeding. Richard Klein has specifically been skeptical of the study as per the New York Times article.

There are still some loose ends that need to be resolved. For example modern Humans and Neanderthals appear to have shared the same territory in Europe for close to 10,000 years. If they were close together for so long, we would expect to see more evidence of Neanderthal admixture in Europeans than say Papuans or Chinese because there is no known presence of Neanderthals in East Asia or Oceania. However Papuans, Chinese and French samples have the same amount of "admixture" as Europeans. If we consider that the OOA migration occurred 80-50kya, and Neanderthals were in Iraq at Shanidar Cave roughly around the same period and were in Europe up until 24000 years ago based on the Gibralter evidence, then we have a much longer period of co-existence, especially for Europeans. The ancestors of the Chinese and Papuans would have dispersed away from Neanderthal regions leaving Europeans and Neanderthals to interact for several thousands of years. The authors of the study would like us to believe that admixture only occurred once in the Middle East, and not any time after despite this long period of coexistence. The study states,

A striking observation is that Neandertals are as closely related to a Chinese and Papuan individual as to a French individual, even though morphologically recognizable Neandertals exist only in the fossil record of Europe and western Asia. Thus, the gene flow between Neandertals and modern humans that we detect most likely occurred before the divergence of Europeans, East Asians, and Papuans. This may be explained by mixing of early modern humans ancestral to present-day non-Africans with Neandertals in the Middle East before their expansion into Eurasia. Such a scenario is compatible with the archaeological record, which shows that modern humans appeared in the Middle East before 100,000 years ago whereas the Neandertals existed in the same region after this time, probably until 50,000 years ago

It is evident that the authors do not address the range overlap of Europeans and Neanderthals. In summary, I suggest that all statements regarding interbreeding should not be considered as facts, but rather should be attributed to their respective studies. Wapondaponda (talk) 19:49, 16 May 2010 (UTC)

One more, we need to recall what occurred with the Ida fossil, there was a huge hullabaloo which turned out to be an over-hyped publicity stunt. I don't know about this case, but stories of Neanderthal admixture do go down well with the press. Wapondaponda (talk) 19:58, 16 May 2010 (UTC)

The relationship of Neanderthals to a more diverse set of modern humans is shown in Table 4 of the research article. The "alternative explanation" is already mentioned in our article. I believe that interbreeding in the Middle East and not so much elsewhere would be consistent with a scenario involving slavery in the Middle East. --Millstoner (talk) 02:39, 17 May 2010 (UTC)

"scenario involving slavery"? What on earth are you talking about? Slavery in the Middle Paleolithic?

Muntuwandi is correct, these are preliminary results. But the results are so unambiguous that they cannot be said to be "controversial". Everybody is surprised, but everybody agrees that the results speak for themselves. The theoretical possibility of "ancient population substructure" would just shift the locus of the admixture into Africa. That the data ' should not be considered as facts, but rather should be attributed to their respective studies' is a truism on Wikipedia, but nevertheless Wikipedia can report undisputed points in its own voice. It is undisputed that these results are recent and subject to further analysis, but it is also undisputed that they are strikingly clear. --dab (𒁳) 08:39, 17 May 2010 (UTC)

"Out of Africa 1" was when homo erectus left Africa, "out of Africa 2" was when the ancestors of the Neanderthals left Africa and "out of Africa 3" was when the ancestors of modern non-Africans left Africa. If prehistoric Africa was genetically subdivided, and if "Out of Africa 2" and "Out of Africa 3" occurred from the same source population, then Neanderthals and non-Africans would be closely related and this relationship would exist without the need for interbreeding. This scenario is not impossible because all three Out of Africa migrations involved passing through Northeast Africa.

What is unambiguous from this study is that the Neanderthal samples shared more genetic lineages with non-African samples than with African samples. The reasons for this pattern are less straight forward than the data. The authors argue that they have ruled out European contamination of Neanderthal DNA, but contamination could potentially explain this pattern. It is also possible that some of these exclusive Eurasian/Neanderthal shared lineages also exist in Africa but have not been identified due to small sample sizes. If we consider that two San individuals are genetically more different from each other than a European and an Asian, anything is possible with wider sampling.

Lastly, the fact that the Papuan and the French sample have the same amount of Neanderthal admixture is highly suspect, and the authors provide no satisfactory explanation for this observation. If Neanderthals and modern humans were capable of interbreeding, they would have done so multiple times in Europe where they co-existed for several thousand years. Europeans should have a lot more Neanderthal admixture than all other populations, but no such pattern is seen.

The study is very interesting, and the Paabo group has a good reputation, but due to some of the anomalies I have mentioned (they do appear in reliable sources), I believe we are still a long way from Neanderthal admixture being an unqualified fact. Wapondaponda (talk) 11:44, 17 May 2010 (UTC)

There is evidence that there were different subgroups or "races" of Neanderthals.[1][2][3] There is also some evidence that they could talk like we do.[4][5][6] Neanderthal brains were as large or larger than modern human brains. There is no reason to assume they exhibited chimp-like behavior. --Millstoner (talk) 12:45, 17 May 2010 (UTC)

Millstoner, you keep going off on entirely weird targets. What with the "slavery" in your last post and the "chimp-like behavior" in this one. Nobody claims Neanderthals had "chimp-like behavior", what does this even have to do with anything?

Muntuwandi, I agree with most of what you say. I may disagree in some details, but this is irrelevant under WP:FORUM. Neanderthal admixture has been revived as a real possibility, but we agree this is still a long way from "unqualified fact". --dab (𒁳) 16:53, 17 May 2010 (UTC)

My specific concern is some of the wording in the article that considers Neanderthal admixture as a fact rather than a hypothesis. Millstoner wrote "An analysis of a first draft of the Neanderthal genome released in May 2010 indicates that interbreeding did occur". Wapondaponda (talk) 18:22, 17 May 2010 (UTC)

well, please fix it. We all agree it's just a hypothesis at this stage. --dab (𒁳) 12:57, 20 May 2010 (UTC)

I changed it to say that interbreeding likely occurred. Taking into consideration the amount of bestiality going on in the world today, it is pretty much a slam dunk that there was some sex going on. The only question was whether that union resulted in fertile offspring. --Millstoner (talk) 01:26, 21 May 2010 (UTC)

Indeed. It's not "bestiality" if it's the same genus, Homo (human). Our best guess today is that admixture occurred, but we cannot be sure. So there you are. --dab (𒁳) 08:48, 21 May 2010 (UTC)

Up until this study, the leading hypothesis was that no interbreeding occurred. The lack of interbreeding was supported by a number of independent lines of evidence. The Y-chromosome and mitochondrial DNA showed no evidence of interbreeding and were consistent with a recent single origin of modern humans. In general Y-chromosome or mitochondrial DNA admixture tends to correlate with Autosomal admixture, so 0% y-DNA or mtDNA admixture, will typically mean 0% autosomal admixture. Autosomal DNA also was supportive of no interbreeding, indeed this recent study by Green et al. still demonstrates that 96-99% of human DNA is not the result of interbreeding. The human fossil record also favors a lack of interbreeding because the two species retained their respective distinct morphologies despite residing in the same territory for several years. The rapid movement of Upper Paleolithic technology from the Middle East into Europe was also interpreted as a replacement of the Neanderthals rather than interbreeding. According to archeologists such as Klein, sediments from caves Europe indicate that the transition was rapid such that it appears that one day Neanderthals inhabited the caves, and the next day it was Cro-Magnons. The information contained in this new study needs to be reconciled with the evidence that made a lack of interbreeding the leading hypothesis. Wapondaponda (talk) 20:02, 21 May 2010 (UTC)

Please see Neanderthal#Genome. --Millstoner (talk) 17:29, 22 May 2010 (UTC)

Muntuwandi, the importance of the 2010 study is precisely that it switched "leading hypotheses". Apart from the "in general Y-chromosome or mitochondrial DNA admixture tends to correlate with Autosomal admixture", none of your points hold any water. Of course Cro-Magnon displaced Neanderthal, this picture doesn't change just because there was some minimal admixture, so all your points on technological or cultural changes are completely beside the point.

as for, "in general Y-chromosome or mitochondrial DNA admixture tends to correlate with Autosomal admixture", that's a rather sweeping statement on an extremely complex question. I would be interested in just how strongly experts feel absence of unbroken matrilineal or patrilineal lines prejudice the likelihood of admixture. To my untrained eye, this doesn't pose a problem at all, but I will be interested in reading an expert opinion saying otherwise. --dab (𒁳) 19:45, 22 May 2010 (UTC)

The Green et al. 2010 is was just published a few days ago, so there has not been enough time yet for responses from other scientists. We would need to hear responses from the numeorous scientist who suppored the "strictly out of Africa" in order to determine what the leading hypothesis is. Tales of "Caveman interbreeding" make great headlines, so the story has gotten a lot of sensationalist publicity in the press. But we shouldn't be carried away with the hype, which was precisely what happened with the Darwinius. Initially the press stated that Darwinius was the oldest fossil of a human ancestor, but it has later revealed the Darwinius is probable not one of the ancestors of humans. For Wikipedia purposes, we need reviews from reliable sources in order to change the leading hypothesis.

It is possible for y-DNA and mtDNA lineages to be lost by drift but autosmal lineages to be retained in a population. But such a scenario is less parsimoniusWapondaponda (talk) 02:40, 23 May 2010 (UTC)

try to keep down the patronizing, I am not "carried away" by press hype. I fully understand the long-standing hypothesis, and the thing this study does to the hypothesis, never mind the press. I also realized Darwinius was all hype after like five minutes. I do not buy your implication that "strictly out of Africa" scholars even have an opinion on this, barring ideological gut feeling, as the "out of Africa" scenario is not affected by the admixture.

Regarding Y-/mtDNA, I understand that you think that "such a scenario is less parsimonius". The point is that I am not convinced and asked for an expert opinion: what are the chances of losing Y-/mtDNA lineages of a minimal admixture (1%) over 1,500 generations. This is not something you can calculate on the back of an envelope, you'll probably need to run a simulation. --dab (𒁳) 10:34, 28 May 2010 (UTC)

Green et al. critique

New study that is critical of the interbreeding hypothesis as suggested by Green et al. 2010. Hodgson; et al. (2010). "Neandertal Genome: The Ins and Outs of African Genetic Diversity". doi:10.1016/j.cub.2010.05.018. {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |last= (help)

Wapondaponda (talk) 13:25, 2 July 2010 (UTC)

Title

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the move request was: page moved. Deacon of Pndapetzim (Talk) 04:37, 18 January 2011 (UTC)

---

This isn't a hypothesis anymore, it's a theory. 99.236.221.124 (talk) 23:59, 9 October 2010 (UTC)

I was just going to say that. Move to Neanderthal admixture theory anyone? Rursus dixit. (^mbork³!) 13:15, 31 December 2010 (UTC)

OK, doing it properly:

{{movereq|Neanderthal admixture theory}}

Neanderthal admixture hypothesis → Neanderthal admixture theory —

reason: the word 'hypothesis' is normally referring to unattested theories without any research trying to solve the question, there is such (IMHO unconclusive) research that both provides support and that speaks against the theory. 'hypothesis' in this context is one candidate for the understatement of the year. Rursus dixit. (^mbork³!) 13:23, 31 December 2010 (UTC)

• Why not just Neanderthal admixture? Powers ^T 19:38, 1 January 2011 (UTC)

Given that we now know admixture exists, it strikes me that "relationship of neanderthals to modern humans" is a more appropriate subject, either for a title or for a section of the article on neanderthals. — Preceding unsigned comment added by Warren Dew (talk • contribs) 02:09, 2 January 2011 (UTC)

I've proposed a merger into Talk:Archaic Homo sapiens admixture with modern humans instead. Please discuss at the discussion page. Warren Dew (talk) 16:26, 7 January 2011 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Relation to Autism

I've copied the following from a section I made on the "Heritability of Autism" page. My only request is that you read before you delete:

The Journal of Evolutionary Psychology just published a paper that supports the hypothesis that the confirmed neanderthal admixture event(s) provided cognitive variations that were subsequently selected for, sometimes causing a locus of deleterious recombinations in the genomes of children with parents who selected one another for those characteristics: http://www.epjournal.net/filestore/EP09207238.pdf

• "People on the autism spectrum are conceptualized here as ecologically competent individuals that could have been adept at learning and implementing hunting and gathering skills in the ancestral environment."
• "The autism continuum could represent a remnant of genetic introgression that took place before humans were the lone species in our genus. Perhaps some of the genes for autism evolved not in our direct ancestral line but in a solitary subspecies which later merged genetically with our line of descent through gene flow."
• "Many of the behavioral and cognitive tendencies that autistic individuals exhibit are viewed here as adaptations that would have complemented a solitary lifestyle. For example, the obsessive, repetitive and systemizing tendencies in autism, which can be mistakenly applied toward activities such as block stacking today, may have been focused by hunger and thirst toward successful food procurement in the ancestral past. Both solitary mammals and autistic individuals are low on measures of gregariousness, socialization, direct gazing, eye contact, facial expression, facial recognition, emotional engagement, affiliative need and other social behaviors. The evolution of the neurological tendencies in solitary species that predispose them toward being introverted and reclusive may hold important clues for the evolution of the autism spectrum and the natural selection of autism genes."
• "This article emphasizes that individuals on the autism spectrum may have only been partially solitary, that natural selection may have only favored subclinical autistic traits and that the most severe cases of autism may be due to assortative mating. "
• "Unfortunately, the genetics, molecular biology and neuroscience of autism are still, relative to many other neurological disorders, shrouded with uncertainty due to their highly complex nature (O’Roak and State, 2008)."
• "A portion of this complexity and uncertainty arises from the relatively large number of distinct susceptibility genes that have been identified, many of which can be completely absent even in pronounced autism (Freitag, 2007). This genetic heterogeneity may be responsible for the clinical heterogeneity..."
• "1. isolated pockets of humans can remain reproductively insulated for long enough to evolve discrepant ecological strategies; 2. such populations can quickly (less than 40,000 years in the South American and Asian pygmies; Cavalli-Sforza, 1986) develop features that vary markedly from the norm; 3. these traits can involve multiple genes at different loci; and 4. interbreeding can result in either continuous or polymorphic variation in subsequent generations. It is interesting to note that, as these indigenous people become assimilated into other gene pools, the genes for short stature will persist and may affect phenotypic variability in sporadic and unpredictable ways for a long time to come."
• "Like other polygenic, continuous traits, the mutations responsible for autism could have been maintained by “environmental heterogeneity,” a form of balancing selection. In other words, the genes responsible for autism may have remained in our gene pool because as social-environmental conditions fluctuated in the past, discrepant genetic polymorphisms, or “multiple alternate alleles,” were favored."

Here are some peer reviewed sources that imply a link between the genes garnered via neanderthal admixture and the genes that code for ASDs:

• Brain development after birth differs between Neanderthals and modern humans (2010, Max Planck Institute for Evolutionary Anthropology) B]

"The development of cognitive abilities during individual growth is linked to the maturation of the underlying neural circuitry: in humans, major internal brain reorganization has been documented until adolescence, and even subtle alterations of pre- and perinatal brain development have been linked to changes of the neural wiring pattern that affect behavior and cognition [9]. The uniquely modern human pattern of early brain development is particularly interesting in the light of the recent breakthroughs in the Neanderthal genome project [10], which identified genes relevant to cognition that are derived in living humans. We speculate that a shift away from the ancestral pattern of brain development occurring in early Homo sapiens underlies brain reorganization and that the associated cognitive differences made this growth pattern a target for positive selection in modern humans."

• A Draft Sequence of the Neandertal Genome

"Mutations in CADPS2 have been implicated in autism (67), as have mutations in AUTS2 (68)."

• Autism, the Integrations of ‘Difference’ and the Origins of Modern Human Behaviour (McDonald Institute for Archaeological Research)

The fact that the male side of the admixture(s) was/were strictly neanderthal would mean that we share none of their mtDNA. This explains the lack of mtDNA abnormality and the existence of mitochondrial dysfunction in people with ASDs: http://www.biomedcentral.com/1471-2350/12/50

• "the frequent observation of concomitant mitochondrial dysfunction and ASD could be due to nuclear factors influencing mitochondrion functions or to a more complex interplay between the nucleus and the mitochondrion/mtDNA."

The neanderthal haplotype described in this 2011 paper is x-linked: http://mbe.oxfordjournals.org/content/early/2011/01/25/molbev.msr024.full.pdf+html

The abstract finishes by saying: "It indicates a very early admixture between expanding African migrants and Neandertals prior to or very early on the route of the out-of-Africa expansion that led to the successful colonization of the planet." [On a side note: This could also explain the unique, cyclical pattern of brutal invasion, cultural assimilation, and intermarriage that is so common in the written history of human civilization. Evidence of mostly patrilineal migrations among early AMHs is just coming out: http://www.pnas.org/content/early/2011/05/24/1100723108 "Ancient DNA reveals male diffusion through the Neolithic Mediterranean route" (May 2, 2011)]

More evidence is cited in this wrongplanet thread: http://www.wrongplanet.net/postp3696657.html#3696657 Slartibartfastibast (talk) 21:31, 10 June 2011 (UTC)

For contrary evidence, see this paper, which finds that autism regularly appears de novo, due to copy number variation mutations. Given that, there seems no need to hypothesize that autism is inherited from Neanderthals. Metageek (talk) 11:57, 23 June 2011 (UTC)

CNV loci would appear in regions undergoing strong selection for gene variants introduced from a hybrid introgression. The coalescent DNA from a bottlenecked admixture would be more genetically homogeneous, causing localized spontaneous deletions/duplications. Also, who hypothesized that autism is inherited from neanderthals? Do you understand what's being proposed here?Slartibartfastibast (talk) 20:21, 20 July 2011 (UTC)

Neanderthal Admixture and non-Africans

The stock photo they are using is horribly outdated, but, this might be useful reference. All Non-Africans Part Neanderthal, Genetics Confirm
— al-Shimoni (talk) 07:01, 19 July 2011 (UTC)

Please Update with latest Paper

Please Update with latest Paper

http://www.pdf-archive.com/2011/08/26/neanderthalautoimmune/neanderthalautoimmune.pdfLhunGrub (talk) 05:56, 27 August 2011 (UTC)

This seems to be unpublished. - SummerPhD (talk) 13:47, 27 August 2011 (UTC)

"Published Online August 25 2011" Slartibartfastibast (talk) 15:38, 27 August 2011 (UTC)

Link to Bipolar Disorder

Evolutionary origin of bipolar disorder-revised: EOBD-R (Accessible PDF)

• "Given evidence of Neandertal contributions to the human genome, the hypothesis is extended (EOBD-R) to suggest Neandertal as the ancestral source for bipolar vulnerability genes (susceptibility alleles). The EOBD-R hypothesis explains and integrates existing observations: bipolar disorder has the epidemiology of an adaptation; it is correlated with a cold-adapted build, and its moods vary according to light and season. Since the hypothesis was first published, data consistent with it have continued to appear."

Slartibartfastibast (talk) 18:19, 9 November 2011 (UTC)