New Type of Ancient Human Found—Descendants Live Today?

But with MH, the DNA still originated in Africa. But the denisovian DNA came from another region thereby making it "Multiregional", no? Yes, the origin of the DNA is primarily from Africa, but the OOA model says that the other DNA came about relatively recently after Africa was left.The MH says that there was already that other DNA there when Africa was last left.Doesn't the fact that the other DNA came from outside of Africa suggest that it was outside after the Africans left? i.e. The MH model. I'm asking.I'm just trying to understand it, I don't care what Jon is arguing.

Hi, CS. Sure thing. I've actually got two different disagreements going on: one with the multiregional hypothesis, and one with Jon.My disagreement about MR is primarily just a semantic one: I agree that there is some genetic diversity in modern humans that clearly didn't come from African H. sapiens; but this explains such a tiny percentage of the data that it hardly seems meaningful to me to try to rewrite the paradigm as a compromise between the two competing theories because of it. It makes more sense to me to just let OoA assimilate the idea that there was some small amount of genetic admixture.That disagreement isn't particularly important to me: you'll see that I haven't put a lot of effort into following up on the responses I've gotten about it. I'm perfectly happy to drop it, in fact.-----The main disagreement I have is with Jon's proposal that the available evidence doesn't point to a directional migration of people out of Africa. So, he's not arguing, like Nuggin, that both OoA and MR are correct: he's turned a minimal vindication of one of MR's claims into a strong challenge against the core of OoA.Jon is convinced that movement of paleo-Africans over great distances is an extraordinary claim, and that we are thus in need of some other mechanism that doesn't involve any people walking outside of their normal habitats. Trace amounts of Neanderthal and Denisovan genetic signatures in some human populations is enough for Jon to decide that we no longer need to resort to such outlandish claims as nomadic hunter-gatherers moving into new territories.I'm trying to reason with him that movement of nomads into new areas isn't really such an outlandish claim, and that his alternative proposals are much more dubious.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. Probably an understatement.----- And, in the meantime, I'm showing you that the movement of nomads into new areas isn't nearly so outlandish that we need to be coming up with various ways to avoid having to resort to it

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Thanks, its much clearer now. And isn't that, pretty much, what the MH model is saying? But it seems to me that the OOA model specifically excludes that assimilation.So, it looks like you're actually agreeing more with the MH. It seems like you think that the MH doesn't include as much from the OOA as it does, and that what inclusion of OOA it should have would thereby make it OOA, but that doesn't look correct from what I've been reading on wiki. OOA seems to exclude any non-African origins while MH incorporates the OOA origin along with other origins for other DNA. Ah well, how about clarity for clarity's sake then? I'm not concerned with Jon's proposal, but the findings shown in the OP do seem to challenge the core of OOA that is that there wasn't any non-African sources for the DNAs.Like, OOA is saying everything came from Africa and now we find something that didn't. That doesn't mean that almost everything didn't come out of Africa, just that some things did. Doesn't that challange OOA?

I think this is best viewed in terms of mechanism. We have two different mechanism for dispersing human DNA. One is gene flow while the other is migration. Both mechanisms can operate at the same time. You can have Paleo-Africans migrating across the globe that do in fact outcompete human species that were already there. These african populations would, according to the OoA mechanism, only breed within their group. However, we all know that humans aren't all that picky. Some outbreeding did occur per the MH mechanism, but it was relatively little compared to the OoA mechanism (at least according to my judgement thus far). Correct. It is 95% OoA and 5% MH, or thereabouts. It is a mixture of the two mechanisms with OoA being the predominant mechanism.

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And isn't that, pretty much, what the MH model is saying?

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No, the MH model says that modern humans largely evolved as a dispersed population, with gene flow throughout.

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But it seems to me that the OOA model specifically excludes that assimilation.

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At this point we're getting into a purely semantic question, but that's not the way I've understood the term OoA to be used, and I've tried to pay attention (and even contribute) to the genetic studies on this issue. My understanding is better reflected in this quotation from Chris Stringer (from Nature, in 2003):"There are two broad theories about the origins of H. sapiens. A few researchers still support a version of the 'multiregional' hypothesis, arguing that the anatomical features of modern humans arose in geographically widespread hominid populations throughout the Pleistocene epoch (which lasted from around 1.8 million to some 12,000 years ago)6. But most now espouse a version of the 'out of Africa' model, although there are differences of opinion over the complexity of the processes of origin and dispersal, and over the amount of mixing that might subsequently have occurred with archaic (non-modern) humans outside of Africa2, 7".

There was some regional DNA (again, about 5%) that made it into the African population that migrated out of Africa. I'm not quite sure what you are asking.The other point worth mentioning is that the Denisova DNA was distinct from African DNA, as distinct as neanderthal and african DNA. What we see in Papau New Guniea is 95% African DNA with a splash of Denisova DNA. If MH were the predominate mechanism you would expect a much stronger input from the Denisova DNA. Yes, there was some interbreeding between the populations, but it appears that it was limited.

I do not disagree that OOA is a contending theory. The problem is with assuming that migration is the only explanation for the current genetic situation and that it is thus the necessary conclusion to draw from the available evidence.There are other ways of explaining the current genetic situation; the recent findings outlined in the OP suggest that those other ways may be more accurate than the current scientific community (OOA proponents) has thought.Jon

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Check out No webpage found at provided URL: Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

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Not when the 'Paleo-African' groups were the largest, most dense, and central groups of the world population. Then the dominance is entirely consistent and expected given either the MH or OOA model. Genetic traits of the central, large, denser groups of a population will naturally dominate the population as a whole whether through hybridization or OOA-type migration. Dominance of African alleles does not necessarily support the OOA model anymore than it supports an alternative model.

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But does this constitute a plausible model? If you're relying solely on the greater pool of chromosomes in sub-Saharan Africa to explain the disparity in where alleles arose, what kind of population structure are you going to have to posit? If you just think about a simple model with two populations (say Europe and Africa), the minimum disparity in population sizes will be with large gene flow rates between them. In that case, for 95% of European alleles to originate in Africa, 95% of the population also had to reside there. But the ancestral effective population size of humans is only ~15,000, for the entire worldwide population. That means you've got something like 700 individuals living in all of Europe. If you factor in restrictions to gene flow and the dilution from the lengthy pipeline alleles had to diffuse through to get from one region to the other, and account for the rest of Eurasia, the actual population would have had to be even smaller. That's simply not a plausible size to be maintaining genetic continuity with Asia and Africa. (Indeed, it's pretty precarious as a population for avoiding local extinction.)There's also the question of when this gene flow is supposed to have been happening. MRH assumes long-term, ongoing gene flow for well over a million years. What the Neandertal and Denisovan genomes show, however, is that there was a great deal of genetic isolation of these populations from the ancestors of modern humans, up to as recently as 40,000 years ago -- and yet you're arguing that the relatedness of modern Europeans and Africans results from gene flow between them. When were the genes flowing?

From Wiki:

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Wikipedia on Multiregionalism:

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The hypothesis holds that the evolution of humanity from near the beginning of the Pleistocene two million years ago to the present day has been within a single, continuous human species. This species encompasses archaic human forms such as Homo erectus and Neanderthals as well as modern forms, which are held to be subspecies, and evolved worldwide to the diverse populations of modern Homo sapiens sapiens. The theory contends that there was some human genetic continuity in various regions of the world as well as gene interchange between the regions.

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Jon

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Check out No webpage found at provided URL: Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

My description of multiregionalism and the one you quoted from Wikipedia are completely consistent.

A comparison of African, Neanderthal, and Denisovan DNA demonstrates that there was a discontinuity.

I've already addressed several of your points earlier on in the thread in replies to other members, especially Bluejay.I will add, however, that the 95% needn't happen over night. Given time and a continued disparity in population density, size, and centrality, one populations genetic information can certainly swamp out the information from another population, without super exoduses taking place from the former to the latter. As an additional tid bit, skeletal evidence seems to suggest that early sapiens in Europe share a larger number of Neanderthal traits than later sapiensi.e., the skeletal evidence seems to be of a 'transitional' sort:

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Wikipedia on Lapedo Child:

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The Lapedo child is a complete pre-historical skeleton found in Portugal. In 1998, the discovery of an early Upper Paleolithic human burial at Abrigo do Lagar Velho, by the team led by pre-history archeologist Joo Zilho, has provided evidence of early modern humans from the west of the Iberian Peninsula. The remains, the largely complete skeleton of an approximately 4-year-old child, buried with pierced shell and red ochre, is dated to ca. 24,500 years BP. The cranium, mandible, dentition, and postcrania present a mosaic of European early modern human and Neanderthal features. This (morphological) mosaic indicates admixture between late archaic and early modern humans in Iberia, refuting hypotheses of complete replacement of the Neandertals by early modern humans and underlining the complexities of the cultural and biological processes and events that were involved in modern human emergence.

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In fact, much of the skeletal evidence we find continually draws the OOA model into question, as we find varieties of regionally continuous traits, seemingly 'transitional' varieties, etc. Now, as the OP brought up, even the genetic evidence is drawing the OOA model into question.Jon

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Check out No webpage found at provided URL: Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

Any on-off discontinuities are a) not inconsistent with MH, and b) not sufficient for speciation.Jon

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Check out No webpage found at provided URL: Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

Is there anything that would be inconsistent with MH?ABE:The MH model that you quoted states that there was a continuous human population from the present back to a million years before present. Are you now arguing that this same model also predicts a discontinuous population for hundreds of thousands of years within that time frame?Edited by Taq, : No reason given.