May 01, 2014

Chris Stringer on Recent Out-of-Africa

An interesting new opinion piece by Chris Stringer in which he affirms the recent Out-of-Africa theory. Some predictions of the multiregionalists were certainly wrong (e.g., they did not predict that East Asians would have any Neandertal ancestry, let alone more than Europeans; and the ancestry of mankind may be even more jumbled than they'd imagined as e.g., it is not Siberians that have regional continuity with Denisovans but rather the faraway Papuans and Australians). On the other hand, the evidence does seem to point for a mostly African origin of Homo sapiens with important details of when and how that remain to be filled.

The fundamental question for me is the balance of divergence and synthesis in human history. Certainly, the fact that Denisova cave and thereabouts in Siberia had at least four divergent human lineages in the last 100-40 thousand years (unknown archaic Eurasians, Denisovans, Neandertals, and finally modern humans) makes modern Eurasians look like twins by comparison. In more recent times, Europeans of a few thousand years ago living in Sweden were more divergent from each other than any two European populations living today. And, while many models would have modern humans and Neandertals splitting from each other and going their separate ways until very recent times, this is hard to reconcile with the fact that apparently Neandertals and Africans became more similar over time during the period where they were supposedly diverging from each other. Was the situation in Africa any different? Morphology does not suggest homogeneity for that continent either.

Certainly, both replacement and gene flow have played a role in human history. The "English" and "Spanish" packages were assembled in Europe by gene flows from hunter-gatherers, farmers, and more recently Anglo-Saxons, Celts, Vikings, Goths, Romans, and Celtiberians (to name a few), but was then exported from Europe. Human history probably abounds in examples of populations that emerge out of a multiregional matrix (even if that matrix does not encompass the entire globe) and then explode in population numbers due to a lucky break or some behavioral or technological advantage.

Trends in Ecology & Evolution Volume 29, Issue 5, p248–251, May 2014
DOI: http://dx.doi.org/10.1016/j.tree.2014.03.001

Why we are not all multiregionalists now

Chris Stringer

Highlights

•DNA data show that archaic introgression into modern human genomes occurred.
•Such introgression is claimed to support the multiregional model for modern human origins.
•This introgression is also claimed to support the lumping of distinct human species into Homo sapiens.
•Comparing models and data still validates a recent African origin model for modern humans and the use of a restricted diagnosis for H. sapiens.

Recent revelations that human genomes contain DNA introgressed through interbreeding with archaic populations outside of Africa have led to reassessments of models for the origins of our species. The fact that small portions of the DNA of recent Homo sapiens derive from ancient populations in more than one region of the world makes our origins ‘multiregional’, but does that mean that the multiregional model of modern human origins has been proved correct? The extent of archaic assimilation in living humans remains modest, and fossil evidence outside of Africa shows little sign of the long-term morphological continuity through to recent humans expected from the multiregional model. Thus, rather than multiregionalism, a recent African origin (RAO) model for modern humans is still supported by the data.

Link

53 comments:

CleverPrimate said...

A primary tenet of the Out of Africa theory is that zero admixture occurred between archaics and the “modern” population that replaced all archaic populations. A primary tenet of the Multi-Regional theory is that admixture with archaics did occur. So in the most basic sense of the word, the Multi-Regional theory has been proved correct.

formerjerseyboy said...

"So in the most basic sense of the word, the Multi-Regional theory has been proved correct." Well, not really .... this reductionist thinking doesn't wash. OOA would have been possible even with some archaic admixture. Trying to disprove one part of a theory does not necessarily disprove the whole formulation. Elsewhere on the Internet (including even Amazon book reviews) multi-regional theorists have pursued lines of argument against OOA with religious zeal.

formerjerseyboy said...

"So in the most basic sense of the word, the Multi-Regional theory has been proved correct." Well, not really .... trying to disprove the whole of OOA by focusing on one element does not prove anything. OOA is still possible with some archaic admixture, regardless what multi-regional zealots will say.

CleverPrimate said...

formerjerseyboy ,
You are twisting my comments. I did not say that the “whole” of OOA had been proved incorrect. I pointed out that on a primary point upon which the two theories inherently disagree, Multi-Regionalism has been proved correct. In my opinion once such a basic assertion of a theory has been conclusively disproved, the rest of the theory must be questioned and re-examined. If that makes me a zealot then I am guilty as charged. I am unconcerned with what may be posted “Elsewhere on the Internet (including even Amazon book reviews) “, I am commenting on what is posted here.

Grognard said...

The fact neanderthal genes are all through africa is better proof. Anyway whatever. Out of Africa is bunk any way you slice it, which becomes more and more clear with time.

Date keeps getting pushed back, archaeology doesn't wash, there's no large brained fossils in africa til they suddenly show up one day (plenty everywhere else), there's very few unique genes in africa. Etc. etc. etc. it's just a crock.

terryt said...

"on a primary point upon which the two theories inherently disagree, Multi-Regionalism has been proved correct".

Agreed, totally.

" Out of Africa is bunk any way you slice it, which becomes more and more clear with time".

Well, no. The majority of modern human genetic makeup has 'recent' origins in Africa. And certainly, in the very long view, H. erectus came from Africa.

Tobus said...

@CleverPrimate:
A primary tenet of the Multi-Regional theory is that admixture with archaics did occur.

The primary tenet of the Multi-Regional theory is that modern population are directly descended from local archaic populations - not merely that admixture with local archaics occurred.

So in the most basic sense of the word, the Multi-Regional theory has been proved correct.

Over 90% of all modern human DNA comes from a common African ancestor, and less than 10% from localised archaic populations. so while neither OOA nor Multi-regional turned out to be exactly correct, OOA was >90% right, Multi-regional <10%.


@Grognard: Out of Africa is bunk any way you slice it

You are welcome to maintain any belief you like, but know that every serious expert in the field disagrees with you.

GailT said...

@CleverPrimate and terryt:

Did you read the Stringer paper? He specifically addresses CP's comments. As Tobus commented, the conventional Multi-Regionalism theory claimed that AMH did not originate in Africa and this has been falsified. We know based on DNA evidence that AMH originated in Africa.

Current DNA evidence indicates that there was minor admixture of AMH with archaic humans as AMH expanded out of Africa. This is not in any way consistent with the claims of folks who still want to believe that AMH originated anywhere but Africa.

We can define a new theory of multiregionalism that included minor admixture with archaics, and perhaps even limited back-migrations of archaics from Eurasia to Africa (although this is still speculative). But this is a radically different theory than the old Wolpoff Multi-Regionalism which we now know is incorrect.

CleverPrimate said...

Tobus,
You are conflating the views of the late Carlton Coon with the Multi-regional theory of Wolpoff and Thorne. I know of no researcher that is arguing for direct descent from archaics to moderns, nor am I. That is a gross oversimplification of and mischaracterization of Multi-regionalism. Admixture with archaics is in my opinion the crux of the theory, not an insignificant foot-note. Now that we know admixture did in fact occur all that is left is to quantify how much and determine the impact of it on modern populations.

CleverPrimate said...

GailT,

“ the conventional Multi-Regionalism theory claimed that AMH did not originate in Africa”

I know of no serious MR researcher making such a claim, and certainly not Wolpoff or Thorne.

I did read the paper and I find Stringer’s comments dismissive. I certainly think that some sort of synthesis between the two theories is in order but I don’t believe that is what Stringer is proposing or has achieved.

GailT said...

"I know of no serious MR researcher making such a claim, and certainly not Wolpoff or Thorne."

That was precisely Wolpoff's theory - Stringer quotes Wolpoff ca 1994 "The evolutionary patterns of three different regions show that the earliest ‘modern’ humans are not Africans and do not have the complex of features that characterize the Africans of that time or any other... There is no evidence of specific admixture with Africans at any time, let alone replacement by them... There is indisputable evidence for the continuity of distinct unique combinations of skeletal features in different regions, connecting the earliest human populations with recent and living peoples."

I don't know if Wolpoff has abandoned his theory, or perhaps modified it to accommodate the overwhelming DNA evidence. But it is clear that several people on this forum still adhere to Wolpoff ca 1990.

In any case, it is important to make the point that Multi-Regionalism of the 1990s is a dead theory, and that if your mean something else by multiregionalism e.g., the population dynamics of archaic humans rather than AMH, it is important to make the distinction between the old Wolpoff theory.

GailT said...

Here are Wolpoff and Hawks in 2000 with an evolving definition of Multi-Regionalism that tries to make it compatible with large scale replacement by Africans:

http://www-personal.umich.edu/~wolpoff/Papers/Multiregional.PDF

The further conclusion that “modern humans originating in Africa constitute the majority of the current gene pool in East Asia” is also
compatible with the multiregional hypothesis, given the stipulation, common to most modern human origins explanations, that until recently more people lived in Africa than in other parts of the world


This is a very different theory than the 1994 version, and I read this as Wolpoff ca 2000 attempting to accommodate the genetic evidence without admitting that Wolpoff ca 1994 was wrong.

Compare this with Hawks in 2014:

Modern humans have more than 90% of their genetic makeup from Africans of the late Middle Pleistocene, comprising one major layer of genetic similarity worldwide. This major layer (whether by massive gene flow or direct population movement) overlies a small contribution from earlier Neandertals, Denisovans, and one or more ancient African populations.
The "out of Africa" layer of genetic similarity is the last global one.


So we have AMH originating in Africa, expanding out of Africa primarily within the last 100,000 years, and replacing archaic humans outside of Africa, with a minor amount of admixture. This is completely incompatible with the Multi-Regionalism theory that was very emotionally debated in the 1980s and 1990s.

Tobus said...

@CleverPrimate:You are conflating the views of the late Carlton Coon with the Multi-regional theory of Wolpoff and Thorne

I stand slightly corrected - as you rightfully point out, Wolpoff's theory is not of direct descent but instead proposes "genic exchanges as the basis of its explanation of how differentiation, geographic variation, and evolutionary change within the human species take place" (Wolpoff 2000). This is still not the case however. The small degree of Neanderthal/Denisovan admixture in modern humans is not the cause of the differentiation, geographic variation and evolutionary change we see in modern humans. Contrary to the Multi-Regional theory, East Asians are different from Europeans are different from Africans not because of their archaic admixture, but almost entirely because of independent drift and selection since divergence from their common ancestors, the sapiens lineage that originated in Africa.

We're still left with a hybrid situation where OOA is 90+% correct, and MR fills in the rest. If further evidence of archaic admixture surfaces (as many predict may happen in Africa), then perhaps the ratio will move more in favour of MR, but for now that's how it stands - the vast majority of modern human variation is "within-species" evolution, not genic exchanges with other species.

CleverPrimate said...

GailT&Tobus,
Fair enough, I concede that I have made my points poorly. I will try to do better in the future.

Rokus said...

'it is important to make the point that Multi-Regionalism of the 1990s is a dead theory'

On the contrary, its opponents have never been so frantic in their efforts to survive Multi-Regionalism. Well, reality seems to favor more multi than regio, though for sure it favors less African. The best answer to the Recent Out of Africa paradygm, including the creationist linguisitic world of Chomsky, is just to forget about it and not paying attention to it. It will wither away all by itself.

'Stringer quotes Wolpoff ca 1994 "The evolutionary patterns of three different regions show that the earliest ‘modern’ humans are not Africans and do not have the complex of features that characterize the Africans of that time or any other...'

Modern Africans are very different from the earliest "cromagnoids", including the Hofmeyr sample that despite archaic features shows a strong affinity with Eurasian Cromagnoids. Early African "moderns" rather cluster with Australians. There are some metrics that correlate more recent modern Africans with the early modern Qafzeh–Skhul hominids of Israël, though it should be clear, as it was from the start, that the lineage leading to modern Africans was not ancestral to non-African modern humans. I am glad the victory of deleted evidence and closed systems was only short-lived and didn't survive its creators.

Misquoting, of course, is the favorite pastime of malevolent opponents. However, contrary to what the above quote may suggest to some, Multi-Regionalism supports the continuity of all archaic humans, including the African lineages.

Mark for Summit/Sunnoco said...

"The best answer to the Recent Out of Africa paradygm, including the creationist linguisitic world of Chomsky, is just to forget about it and not paying attention to it. It will wither away all by itself."

IMHO it is very dangerous for science when scientists take the view that contrary theories to their own do not have to be addressed. The more "ridiculous" a theory is the easier it ought to be to blast it to bits. Each new great advance seems outlandish to those who hold the prevailing view of the time. How does science advance if those who wear its mantle simply ignore or dismiss without debate challenges to the paradigm? When I was a child "everyone knew" dinosaurs were like big lizards, the idea that they were more bird than lizard was beyond consideration....

CleverPrimate said...

Rokus said...
'it is important to make the point that Multi-Regionalism of the 1990s is a dead theory'

On the contrary, its opponents have never been so frantic in their efforts to survive Multi-Regionalism. Well, reality seems to favor more multi than regio, though for sure it favors less African. The best answer to the Recent Out of Africa paradygm, including the creationist linguisitic world of Chomsky, is just to forget about it and not paying attention to it. It will wither away all by itself.


Agreed, wholeheartedly, and I intend to follow your advice.

terryt said...

"We can define a new theory of multiregionalism that included minor admixture with archaics, and perhaps even limited back-migrations of archaics from Eurasia to Africa (although this is still speculative). But this is a radically different theory than the old Wolpoff Multi-Regionalism which we now know is incorrect".

True. But we still have some regional continuity but the extent of genetic movement has been grossly under-estimated. For example the Denisovan element in Papuans quite probably goes back to a pre-modern human population in SE Asia. It seems that although the Denisova genetic combination was originally West Eurasian it may be associated with H. heidelbergensis. The SE Asian connection suggests some ancient movement of an H, heidelbergensis-related population to SE Asia at some time. Possibly related to the development of H, soloensis from H. erectus in the region. We also have no idea if the EDAR370A mutation arose in the modern population by mutation or introgression from an Archaic population. Some researchers mention without qualification admixture from an as yet unknown East Asian Archaic population.

And I did say, ' The majority of modern human genetic makeup has 'recent' origins in Africa. And certainly, in the very long view, H. erectus came from Africa'.

Locrian said...

I remember hearing Thorne give a talk on this in 1990. Multi-regionalism seems, and seemed to me at the time, to be simply contrary to evolutionary theory. Isolated populations diverge from one another by drift and differential selection (adaptation). On the time scales we are talking about Asians, Africans and Europeans should have diverged so much that we would not have the same species, or be on the verge of having different species. Multi-regionalists seem to have the idea that somehow all the different isolated populations would be kept in more of less lock-step, but no explanation of how that could be so.

I also remember Thorne characterising OoA as postulating wave after wave of murderous Africans wiping out preceding populations, but I can’t recall now why it was necessary to have more than one such wave.

CleverPrimate said...

“Multi-regionalists seem to have the idea that somehow all the different isolated populations would be kept in more of less lock-step, but no explanation of how that could be so. “

IMHO, Multi-regionalists have an elegantly simple explanation for this; gene flow. Gene flow, admixture, introgression, hybridization, whatever term that you may prefer, it is a primary driver of the species wide evolution. As I keep saying, it is not a footnote or otherwise insignificant detail of the theory; it is the very essence of the theory. Without it the theory has no legs to stand on.

Rokus said...

@Sunnoco,
'How does science advance if those who wear its mantle simply ignore or dismiss without debate challenges to the paradigm? When I was a child "everyone knew" dinosaurs were like big lizards, the idea that they were more bird than lizard was beyond consideration....'

Bird-like dinosaurs were limited to the branch of tetanuran theropods, and even within this branch species disposed of different stages of thermoregulation: Archaeopteryx might well have been an ectotherm. Ruben (1995) explains the issue in all its evolutionary complexity. Nevertheless, I consider it highly unproductive to continue the same discussion on the tenant that dinosaurs were like big lizards anyway. As far I can remember this has always been disputed and only popular science and scientific outsiders drawing on some kind of perceived virtual consensus, like with Kurganism, Chomsky and ROA, pretended that "everybody knew". The problem with such an attitude is its highly unscientific to maintain a closed system a as hypothesis. In Popperian terms of "being scientific", you can't falsify the big lizard hypothesis since warm-blooded dinosaurs would be considered contradictio in terminis and easily dismissed as non-dinosaurs beforehand. Evidence of talking archaics may always be dismissed as non-AMH by Chomsky. Archeological evidence of absense will never be accepted by Kurganists, while the most severe cases of Kurganists even charge their cavalery against mtDNA H evidence in Mesolithic Iberia. Out of Africa was based on the assumption that human species didn't interbreed because biologically they couldn't, but they could. The very basis of any single origin of the modern human species turned out to be quicksand, to the result that insisting on an African origin reduces to nothing but begging the question. Now ROA proponants insist on the same validity of their theory while the imperative is actually floating in the air, they actually attempt to crucify Popper. There is no benefit in discussing anything that does not comply to the standards of science.

German Dziebel said...

@gailT

"We know based on DNA evidence that AMH originated in Africa."

More nonsense from my old friend, GailT. There's no DNA evidence that AMH originated in Africa. "AMH" is a paleobiological term and there's no ancient DNA from the so-called "AMH" available to date to indicate that living humans - from whom we have plenty of DNA - originated in Africa.

@Tobus

"Over 90% of all modern human DNA comes from a common African ancestor, and less than 10% from localised archaic populations. so while neither OOA nor Multi-regional turned out to be exactly correct, OOA was >90% right, Multi-regional <10%."

No, this is your wishful thinking inspired by Stringer's wishful thinking. In the absence of ancient DNA from Africa, there's no proven descent of modern humans from an African ancestor. We need to see what DERIVED alleles are shared between humans and African hominins and whether they are more frequent in modern Africans vs. Eurasians. A bulk of African DNA is not found outside of Africa suggesting that there was no expansion out of Africa. A small amount of Eurasian DNA (including those alleles shared with Eurasian-specific Neandertals and Denisovans) is found in Africa. We know that "archaic" and modern Eurasians share some DERIVED (hence, "modern") DNA with Eurasian archaics (which corresponds to higher linguistic diversity in America, Sahul and parts of East Asia), while Africans share some ancestral (hence, "archaic") DNA with chimps and this corresponds to low linguistic diversity in modern Africans. So for now, as the evidence stands, modern humans originated off of a Eurasian hominin source, experienced at first isolation (that allowed them to accumulate their specific mutations unknown in Eurasian hominins) and then experienced "archaic" admixture in parts of Eurasia and especially in Africa that affected a number of loci. Both out-of-Africa and Multiregional are incorrect (and correct in some respects). OOA piggybacked on MR's idea that modern Africans originated from an African hominin but mechanically extended this African lineage across the globe implying that it replaced all other continent-specific ones. The latter claim has been falsified, which eliminated any meaningful difference between MR and OOA. As Alan Templeton once pointed out, OOA is a subset of MR. OOA has failed to define "modern humans" and why this human modernity should be thought of as having originated in Africa. That was the job of a single-origin model, but instead it simply amplified some of the tenets of the MR model without furnishing much new. In this sense, OOA is a fluke (if not a hoax, using Stringer's own term).

The only real difference is between a New World and an Old World (OOA/MR) origins of modern humans.

Locrian said...

“IMHO, Multi-regionalists have an elegantly simple explanation for this; gene flow. Gene flow, admixture, introgression, hybridization, whatever term that you may prefer, it is a primary driver of the species wide evolution. As I keep saying, it is not a footnote or otherwise insignificant detail of the theory; it is the very essence of the theory. Without it the theory has no legs to stand on.”

I appreciate your addressing this point, Clever Primate, and doing so in a frank manner. But the problem as I see it is that there is not going to be a lot of admixture for very sizeable parts of the world. What admixture was there for Australian Aborigines? None. Same for New Guinea Highlanders; also South American Indians in remote locations. Only once the World’s population grew to a reasonable size, so that we were all bumping up against one another do we get a lot of admixture, spread around generously. But for 60,000 years many parts of the world have been isolated and in-breeding.

terryt said...

@ Locrian:

"Isolated populations diverge from one another by drift and differential selection (adaptation)".

I think you under-estimate the role of hybridization in species' evolution. Evolution involves two contradictory processes. Inbreeding is required to produce individuals with double recessive genetic mutations. Therefore, as you hint, drift and selection act more effectively on smaller populations. But to ensure long-term survival populations need to be of considerable size.

As a result it seems that evolution is the product of the complex interplay between inbreeding and hybrid vigour. The idea that a single, small population left Africa and gave rise to all surviving non-Africans is actually an impossible scenario. Dienekes' recent post on Neanderthals shows hybridization in the human line goes way back to Australopithecus times:

http://dienekes.blogspot.co.nz/2014/05/archaic-admixture-in-eurasians-with.html

Another very interesting book, if you are at all interested in ornithology is "The Birds of Northern Melanesia" by Mayr and Diamond. They suggest hybridism has been a driving force in the formation of subspecies across Melanesia:

http://www.amazon.com/The-Birds-Northern-Melanesia-Biogeography/dp/0195141709

@ CleverPrimate:

"IMHO, Multi-regionalists have an elegantly simple explanation for this; gene flow. Gene flow, admixture, introgression, hybridization, whatever term that you may prefer, it is a primary driver of the species wide evolution. As I keep saying, it is not a footnote or otherwise insignificant detail of the theory; it is the very essence of the theory. Without it the theory has no legs to stand on".

I agree.

CleverPrimate said...

Locrian,
Multi-regionalism assumes that no population was ever completely isolated, at least not long enough to reduce gene flow to zero. This would apply to Australian and Papua/New Guinea populations as well, although those populations do show signs of being the most isolated and for the longest period of time.

terryt said...

"What admixture was there for Australian Aborigines? None. Same for New Guinea Highlanders"

There was obviously admixture before their ancestors reached both regions as shown by the presence of Denisovan genes in, especially, New Guinea natives.

Tobus said...

@German:
In the absence of ancient DNA from Africa, there's no proven descent of modern humans from an African ancestor

Of the two primary branches of mitochondrial DNA, one leads solely to African lineages while the other leads to some African and all non-African lineages... that's hard to reconcile with a non-African origin.

while Africans share some ancestral (hence, "archaic") DNA with chimps

ALL modern humans share some 97% of their DNA with chimps, there's no need to single out Africans.

and this corresponds to low linguistic diversity in modern Africans

Firstly, linguistics can only go back a few thousand years while the human/chimp divergence was around 6 million years ago and the African/non-African one about 100,000 years ago. You are positing a correlation across timescales with at least several orders of magnitude of difference. Modern language divergence has a infinitely more to do with recent migration patterns than chimp DNA.

Secondly, Africa ranks second only to Asia in terms of languages spoken, and has some of the highest linguistic density hotspots in the world (Nigeria has over 500 languages for instance).

German Dziebel said...

@Tobus

"Of the two primary branches of mitochondrial DNA, one leads solely to African lineages while the other leads to some African and all non-African lineages... that's hard to reconcile with a non-African origin."

It's very easy to reconcile with a non-African origin as the African-specific "branch" may have introgressed from African "archaics." Otherwise, it would've been found outside of Africa along the putative out-of-Africa exit route just like it's abundantly found in African Americans, which represent the outcomes of the only uncontroversial out-of-Africa migration.

"ALL modern humans share some 97% of their DNA with chimps, there's no need to single out Africans."

Mathematics has been your weak spot lately - we're talking about the 3% not the 97%.

"Firstly, linguistics can only go back a few thousand years while the human/chimp divergence was around 6 million years ago and the African/non-African one about 100,000 years ago...Africa ranks second only to Asia in terms of languages spoken, and has some of the highest linguistic density hotspots in the world (Nigeria has over 500 languages for instance)."

I see your knowledge here is non-existent. To keep it simple, Africa has 20 language stocks as compared to 140 in the New World and some 60 in Papua New Guinea. The divergence between the latter two sets of language stocks can easily take 100,000 years. We're not talking about language divergence in the context of the chimp/non-chimp split.

terryt said...

"Otherwise, it would've been found outside of Africa along the putative out-of-Africa exit route"

I've asked you before to provide even one valid reason why that should be so. I give you another chance here. Or is this claim another example of your creationist viewpoint and complete lack of understanding of evolutionary biology? On reflection it is certainly an example of that viewpoint because:

"it's abundantly found in African Americans, which represent the outcomes of the only uncontroversial out-of-Africa migration".

Are you now claiming African-Americans contain a fully representative sample of African haplogroups?

"To keep it simple, Africa has 20 language stocks as compared to 140 in the New World and some 60 in Papua New Guinea".

Simply the random effect of classification systems. New Guinea languages have, at times been reduced to just two basic families, although not everyone agrees. When Greenburg and Ruhlen classified African languages into four groups everyone applauded. But when they suggested American languages form just three families the uproar was tremendous. Seems most people wanted to believe America had been settled since ancient times. I've yet to see any realistic alternative language classification for America that effectively replaces Greenburg and Ruhlens system.

Tobus said...

@German:
It's very easy to reconcile with a non-African origin as the African-specific "branch" may have introgressed from African "archaics."

Except that both branches have the same origin, so neither came from "archaics".

we're talking about the 3% not the 97%.

... and all modern populations share some of their 3% with chimps that the others don't, again, no reason to single out Africans.

To keep it simple, Africa has 20 language stocks as compared to 140 in the New World and some 60 in Papua New Guinea. The divergence between the latter two sets of language stocks can easily take 100,000 years.

It could easily also take 10,000 years - all known linguistic "stocks" are within that time frame, there's simply no possibility of going further back in time in that field (non-written languages leave no historical traces). It's largely all guesswork within that timeframe already.

The higher number of Amerindian language "stocks" compared to African ones is almost certainly connected with the relative isolation of Amerindian sub-populations compared to African sub-populations - if populations are sharing language they're likely sharing genes as well, and vice versa.

We're not talking about language divergence in the context of the chimp/non-chimp split.

Are you taking back your extremely implausible "Africans share some ancestral (hence, 'archaic') DNA with chimps and this corresponds to low linguistic diversity in modern Africans." statement then?



German Dziebel said...

@Tobus

"Except that both branches have the same origin, so neither came from "archaics"."

This is your unwarranted assumption, not a fact. People have no problem interpreting Y-DNA hg A00 as an "archaic" lineage (http://www.sciencedirect.com/science/article/pii/S0002929713000736). I'm just expanding the same logic to cover Y-DNA hgs A and B since they are African-specific, less frequent than hg E in Africa and noticeable more divergent than the rest of the Y-DNA lineages found in living humans.

"... and all modern populations share some of their 3% with chimps that the others don't, again, no reason to single out Africans."

If you look at Fig. S9 at http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004353#pgen.1004353.s010, you'll see that Africans are uniquely chimp-shifted, while non-Africans are Neandertal and Denisovan shifted. By this token alone, non-Africans are more modern (or derived) than Africans. I interpret it as "archaic introgression" in Africa from extinct hominins for which we don't have ancient DNA to match the ancient DNA evidence we have for Neandertals and Denisovans. It's those archaic Africans that were closer to chimps because less evolved from them, not modern Africans. So, Africans are pulled toward chimps not because they are less evolved from them than non-Africans but because Asians who colonized Africa absorbed a bunch of archaic lineages in Africa. Just like Papuans are pulled toward Denisovans because the latter admixed into the former, not because the former descended from the latter and everybody else descended from Papuans. Out-of-Africanists are stuck with interpreting the greater proximity between Africans and chimps as "common descent", which makes modern Africans the only surviving "archaic" population from which non-Africans evolved into a fully modern form.

"The higher number of Amerindian language "stocks" compared to African ones is almost certainly connected with the relative isolation of Amerindian sub-populations compared to African sub-populations - if populations are sharing language they're likely sharing genes as well, and vice versa."

yes, the fragmented linguistic landscape in America and Papua New Guinea follows nicely the genetic pattern of higher Fst, lower heterozygosity precisely in those areas.

"Are you taking back your extremely implausible "Africans share some ancestral (hence, 'archaic') DNA with chimps and this corresponds to low linguistic diversity in modern Africans." statement then?"

Just forget about the chimps. Lower linguistic diversity in Africa is consistent with the later colonization of Africa from areas with greater linguistic diversity. Higher genetic diversity in Africa is consistent with the absorption of archaic African hominin lineages into the incoming Asian population(s). Those archaic Africans who got absorbed either didn't have a language that the incoming modern humans could adopt and speak, or there was a complete language shift. In both cases, this introgression didn't impact linguistic diversity in Africa.

Tobus said...

@German:
This is your unwarranted assumption, not a fact.

Not mine, but every established researcher's in the area, warranted by study of the SNP patterns of each branch. I'm sure you have your own alternative interpretation, but given your extremely unsound methods of interpreting f3/f4 stats, I'll stick with the interpretations of those people who've actually studied in the field.

If you look at Fig. S9 at http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004353#pgen.1004353.s010

A PCA? I thought you said PCA's were inaccurate and outdated? Or is that only when they say something you don't like?

you'll see that Africans are uniquely chimp-shifted, while non-Africans are Neandertal and Denisovan shifted.

For once I'd like you to actually consider what the data represents before jumping to a fantastic conclusion based purely on the pretty pictures. This PCA is measuring how modern populations fall in terms of the genetic difference between the 2 archaics and chimps - it's not measure of affinity across the genome. We know that all non-Africans have archaic admixture so it's obvious that they're going to be slightly closer to the archaic side than the chimp side - in the component (ie at those sites) where archaics differ from chimps, non-Africans will have a few more archaic alleles than chimp ones, and vice versa. If the same test were made using an archaic that admixed into Africans as the reference then we'd see the non-Africans appear "shifted" towards chimps. What this PCA makes very clear is that all modern humans cluster very tightly as a distinct lineage - none of them is particularly "archaic" or "chimp-like" relative to the others and they have much more in common with each other than with the other lineages.

Africans are pulled toward chimps not because they are less evolved from them than non-Africans but because Asians who colonized Africa absorbed a bunch of archaic lineages in Africa.

While we're thinking deeper, lets look at why admixing with an archaic can't make you both more chimp-like AND more heterozygous, only one or the other. Heterozygosity is the measure of sites that have both a derived and an ancestral allele. For an introgression to make you more like a chimp, it has to take one of your derived alleles and replace it with the ancestral, chimp-like one. Doing so, by definition, has to *reduce* your heterozygosity since you've now lost your derived allele. Conversely, for an introgression to increase your heterozygosity it has to add a derived allele to one of your double-ancestral sites, hence making you *less* chimp-like. If admixture increases heterozygosity it is combining the two non-chimp elements of the source populations, leading to an ultimately less-chimp genome. If admixture pulls towards chimps then it's replacing some of the existing non-chimp heterozygosity with the chimp-like ancestral state, leading to a less-heterozygous genome. You can't have it both ways.

Just forget about the chimps

Certainly, I've got no idea why you brought them up in regards to language in the first place

Lower linguistic diversity in Africa is consistent with the later colonization of Africa from areas with greater linguistic diversity.

Except that Africa doesn't *have* low linguistic diversity - it's got extremely *high* linguistic diversity, it's just African languages are more interconnected than in America or New Guinea, where sub-populations remained largely isolated. All this however is attributable to migration patterns in the last few thousand years, not prehistoric admixture events. I don't think you're going have much success trying to use linguistics to determine human origins, it simply doesn't have any accuracy at the timescales we're talking about.

German Dziebel said...

@Tobus

"your extremely unsound methods of interpreting f3/f4 stats."

My interpretations of f3/f4 stats are extremely sound. By scientific standards. The data is not perfect of course because those are relatively new methods. The reason you refuse to accept them is because they violate your vision of reality. You resort to pseudomathematical arguments to question interpretations by a professional scientist.

Don't assume your mathematical critique has any validity. It's plain baloney as you haven't produced a single actual calculation.

"Not mine, but every established researcher's in the area."

I question it on the basis of superior education, logic, methodology and cross-disciplinary factual mastery.

"A PCA? I thought you said PCA's were inaccurate and outdated? Or is that only when they say something you don't like?"

That's all we have in this case.

"We know that all non-Africans have archaic admixture so it's obvious that they're going to be slightly closer to the archaic side than the chimp side."

What you are missing (likely intentionally) is that ALL humans (Africans included) are shifted toward Denisovans and Neandertals compared with chimps (Fig. S9). Within that group of Eurasian-hominin-shifted populations, Africans are chimp-shifted compared to non-Africans.

"in the component (ie at those sites) where archaics differ from chimps, non-Africans will have a few more archaic alleles than chimp ones, and vice versa."

Exactly. Africans are more "archaic" and non-Africans are more "modern" that is.

"What this PCA makes very clear is that all modern humans cluster very tightly as a distinct lineage - none of them is particularly "archaic" or "chimp-like" relative to the others and they have much more in common with each other than with the other lineages."

It is the same ancestral lineage but the plot doesn't tell us where this lineage originated. Remember, out-of-America doesn't question the unity of the human lineage. It proposes an alternative homeland for this lineage. Africans are closer to chimps and non-Africans are closer to Neandertals and Denisovans. All humans are more like Neandertals and Denisovans than like chimps. It's just logic that the origin of modern humans must be non-African with the secondary, African-specific proximity to chimps stemming from admixture with extinct African hominins. Unless you of course believe that Africans descended straight from chimps. Knowing that you believe MA-1 originated from UFOs, I wouldn't be surprised if you interpreted Darwinism that literally.

"Heterozygosity is the measure of sites...can't have it both ways."

There are different scenarios for different sites. There are indeed sites (e.g., EDAR) that's ancestral-homozygous (EDAR-) among Africans, while it's heterozygous among Amerindians and East Asians (they have both EDAR- and EDAR+). So this would fit your second scenario - Africans are less heterozygous than non-Africans. In other cases, a mix of two homozygous populations - a modern human one fixed on a derived allele and an archaic African one fixed on an ancestral one yields a heterozygous population in Africa. In both cases, archaic admixture results in Africans shifted more toward chimps thanks to the absorbed ancestral homozygosity.

Tobus said...

@German:
My interpretations of f3/f4 stats are extremely sound. By scientific standards. The data is not perfect of course because those are relatively new methods. The reason you refuse to accept them is because they violate your vision of reality.

The reason I doubt them is because they have no mathematical foundation and because they lead to contradictory results. I'm not sure how you consider them "scientific", you certainly haven't provided a scientific explanation of how you arrived at them.

I question it on the basis of superior education, logic, methodology and cross-disciplinary factual mastery

Funny, I accept it on the exact same basis. I guess we have different opinions on what "superior" and "mastery" mean - but good to see you don't suffer from a deflated ego.

Within that group of Eurasian-hominin-shifted populations, Africans are chimp-shifted compared to non-Africans.

Unless of course non-Africans have some Neandertal/Denisovan admixture, then it would be non-Africans being archaic-shifted while Africans remained at the non-shifted position.

Exactly. Africans are more "archaic" and non-Africans are more "modern" that is.

What you are missing (likely intentionally) is that this is only in those alleles that are by definition ancestral in Africans and derived in non-Africans. If instead we used an reference that was more African to begin with, it would be the non-Africans who would appear "chimp-shifted".

There are different scenarios for different sites...

Derived alleles will only become fixed under strong selection. Since the majority of mutations are non-functional, the number of homozygous ancestral sites will greatly outnumber the number of homozygous derived sites, hence your first scenario will be more prevalent than your second one. Net effect, admixture either makes you more ancestral, or more heterozygous, but not both.

Rokus said...

"Exactly. Africans are more "archaic" and non-Africans are more "modern" that is."

'What you are missing (likely intentionally) is that this is only in those alleles that are by definition ancestral in Africans and derived in non-Africans. If instead we used an reference that was more African to begin with, it would be the non-Africans who would appear "chimp-shifted".'

Indeed, this is something I wanted to comment on earlier. On this basis the African populations are not truly "chimp-shifted", since this would imply that Africans feature shared drift with chimps. There is no sound reason to assert such a thing.

German Dziebel said...

@Tobus

"I'm not sure how you consider them "scientific", you certainly haven't provided a scientific explanation of how you arrived at them."

I didn't. Skoglund did. In two different places: in the table I referenced and in the "tree." Let's move on.

"Funny, I accept it on the exact same basis. I guess we have different opinions on what "superior" and "mastery" mean - but good to see you don't suffer from a deflated ego."

It's not ego. These are just facts. Superiority comes from the diversity of sciences studied, from the diversity of top places attended and practiced and from anthropological reflexivity. "Mastery" means an ability to juggle different facts from vastly diverse disciplines and seeing connections between them. Conventional human origins research is very one-sided: stones and bones for most and stone, bones and genes for some. A better approach is to add memes into the mix (linguistics, kinship studies, ethnology, musicology, etc.), so it should be stones, bones, genes and memes with the theory-building task shifted from the former two to the latter two.

"Unless of course non-Africans have some Neandertal/Denisovan admixture, then it would be non-Africans being archaic-shifted while Africans remained at the non-shifted position."

Non-Africans can be (and are) more Neandertal/Denisovan shifted but Africans (even in an unshifted position) will still be more Denisovan/Neandertal shifted than chimp shifted. For out-of-Africa to work you would need to have all of humans more chimp shifted than Neandertal/Denisovan shifted. This is not the case. Hence, out-of-Africa's picture of reality is the opposite from what the data is telling us.

"If instead we used an reference that was more African to begin with, it would be the non-Africans who would appear "chimp-shifted"."

Do you have an example of a locus in which this is indeed the case? Is it again one of your possible scenarios that you prefer to interpret as an incontroversial fact on which to rest the whole theory of human origins? I've only seen PCAs in which Africans are uniquely chimp shifted. See another example at http://anthropogenesis.kinshipstudies.org/2012/03/american-indians-neanderthals-and-denisovans-pca-views/.

"Net effect, admixture either makes you more ancestral, or more heterozygous, but not both."

In fact this made me recall that African populations differ in terms of their heterozygosity vs. prevalence of ancestral alleles. African farmers tend to be more heterozygous than African foragers. Hadza, who were isolated for quite a while until most recently, for instance, are shifted the most back to the Amerindian pole of low heterozygosity. San are less heterozygous than Bantu. This undermines out-of-Africanists' claim that the heterozygosity cline depicts an out-of-Africa migration but it does suggest that Africans can be seen as both heterozygous and archaic-admixed - different groups of Africans are either one or the other.

Tobus said...

@German:
I didn't. Skoglund did. In two different places: in the table I referenced and in the "tree."

Skoglund doesn't make any inference about shared ancestry between X populations in the f3 stats, nor about relative affinity of X to various B populations in the f4 stats. These are interpretation you invented and have yet to provide a scientific explanation of how they work.

Do you have an example of a locus in which this is indeed the case?

No I don't, but it's called logic. If we measure Africans on a chimp-to-non-African range the Africans will appear "shifted" to chimps compared to other non-African. If we measure non-Africans on a chimp-African scale then non-Africans will be closer to chimps than other Africans. Try to imagine the distribution of the alleles that make up each component being used as the axis, you'll see that using Neandertal/Denisovan-specific genes creates an inherent bias that would be flipped if an archaic African (if one even exists) were used.

This undermines out-of-Africanists' claim that the heterozygosity cline depicts an out-of-Africa migration but it does suggest that Africans can be seen as both heterozygous and archaic-admixed - different groups of Africans are either one or the other.

You don't think the varied heterozygosity could be possibly be caused by varied admixture within the various non-archaic African groups?

German Dziebel said...

@Tobus

"These are interpretation you invented and have yet to provide a scientific explanation of how they work."

I didn't invent anything. These are just data patterns.

"No I don't, but it's called logic. If we measure Africans on a chimp-to-non-African range the Africans will appear "shifted" to chimps compared to other non-African. If we measure non-Africans on a chimp-African scale then non-Africans will be closer to chimps than other Africans. Try to imagine the distribution of the alleles that make up each component being used as the axis, you'll see that using Neandertal/Denisovan-specific genes creates an inherent bias that would be flipped if an archaic African (if one even exists) were used."

You need to bring up an actual example. Africans are everywhere closer to chimps than non-Africans. Neandertals and Denisovans have derived alleles that they share with non-Africans (and those are ancestral in chimps and most Africans).

"You don't think the varied heterozygosity could be possibly be caused by varied admixture within the various non-archaic African groups?"

You mean that Africans are a mix of non-African modern human populations only, without an archaic substrate?

Tobus said...

@German:
fricans are everywhere closer to chimps than non-Africans.

By "everywhere" you mean you have other data? Or just this single Chimp->Neandertal/Denisovan PCA?

You mean that Africans are a mix of non-African modern human populations only, without an archaic substrate?

Nope, I mean that Africans are a mix of various African modern human lineages. There is enough scope for genetic drift and admixture in and between modern human lineages in Africa over the last 150-200ya to explain current African heterozygosity patterns without the need for non-sapiens admixture. (Although I personally suspect it probably did happen on a relatively small scale, like it did in Eurasia)

German Dziebel said...

@Tobus

"By "everywhere" you mean you have other data? Or just this single Chimp->Neandertal/Denisovan PCA?"

I gave you a link to another PCA reproduced on my own site (which BTW you need to study in depth), but you decided to go back to fact denial tactics. I thought PCA was your favorite genre, which gives us "absolute genetic distance."

The whole premise of Neandertal/Denisovan admixture is based on the fact that Africans have ancestral matches with chimps, while non-Africans have derived matches with the Eurasian hominins at certain sites. Are you suggesting that if we find an African archaic hominin DNA it will show the same pattern of unique derived alleles shared with modern Africans corresponding to chimp-Neandertal-Denisovan-human ancestral matches?

"Nope, I mean that Africans are a mix of various African modern human lineages. There is enough scope for genetic drift and admixture in and between modern human lineages in Africa over the last 150-200ya to explain current African heterozygosity patterns without the need for non-sapiens admixture."

The very dates of 150-200kya suggest "archaic" admixture in Africa (which, BTW, could have brought African-specific derived alleles into the modern African gene pool) because the behaviorally modern human record outside of Africa is 50kya at best and it's highly unlikely that modern humans were stuck in Africa for 150-100kya before migrating out.

Tobus said...

@German:
I gave you a link to another PCA reproduced on my own site

It's the same component, chimp-> Eurasian archaic.

The whole premise of Neandertal/Denisovan admixture is based on the fact that Africans have ancestral matches with chimps, while non-Africans have derived matches with the Eurasian hominins at certain sites. Are you suggesting that if we find an African archaic hominin DNA it will show the same pattern of unique derived alleles shared with modern Africans corresponding to chimp-Neandertal-Denisovan-human ancestral matches?

If it admixed with Africans, then of course. An SNP is where the ancestral allele has mutated to a derived version in a specific lineage - any alleles that can be used to identify ancestry is going to be "chimp-like" in those populations that don't have that ancestry.

The very dates of 150-200kya suggest "archaic" admixture in Africa ... because the behaviorally modern human record outside of Africa is 50kya at best

But we're talking about genetically modern, not behaviourally modern... there have been genetically modern humans in Africa for some 150-200k years, plenty of time for drift and admixture to produce the levels of heterozygosity we see today.

German Dziebel said...

@Tobus

"But we're talking about genetically modern, not behaviourally modern... there have been genetically modern humans in Africa for some 150-200k years, plenty of time for drift and admixture to produce the levels of heterozygosity we see today."

We don't have a single DNA from "genetically modern humans" in Africa. There are no living human populations that are genetically modern but behaviorally not. Hence the very existence of genetically but not behaviorally modern humans in Africa prior to 50,000 years is a myth derived from fragmentary and ambiguous skull remains. Alternatively, there's a clear cluster of modern human skulls from Hofmeyr in Africa to Lagoa Santa in Brazil that fits the behavioral modern time horizon. The Hofmeyr skull is not closer to 'anatomically modern humans" in Africa or to modern Africans than any other skull from this group.

German Dziebel said...

@Tobus

"It's the same component, chimp-> Eurasian archaic."

And what did you expect to see? An African archaic?

"If it admixed with Africans, then of course. "

And what would you expect if Africans descended from it and then non-Africans descended from Africans?

terryt said...

"We don't have a single DNA from "genetically modern humans" in Africa".

Not only do we lack any DNA from America before some 10,000 years ago we lack any human skeletal material at all from that age, and only unconvincing evidence for any humans at all in America before 15,18,000 years ago. But that has not prevented you from postulating all sorts of unlikely scenarios. Perhaps a PhD in Dancing with Indians exempts you from having to display consistency.

"There are no living human populations that are genetically modern but behaviorally not".

Nor would we expect to find such. 'Modern behaviour' has nothing to do with genetics and so has had time to spread widely through all existing human populations.

"there's a clear cluster of modern human skulls from Hofmeyr in Africa to Lagoa Santa in Brazil that fits the behavioral modern time horizon".

The Lagoa Santa remains are some 11,000 years old. Are you now claiming that behavioural modernity originated as recently as that time?

"The Hofmeyr skull is not closer to 'anatomically modern humans' in Africa or to modern Africans than any other skull from this group".

Perhaps not. But it is certainly older than anything so far discovered in America.

Tobus said...

@German:
We don't have a single DNA from "genetically modern humans" in Africa.

I think the Yoruba, San and Massai represented in HapMap would disagree with that statement, being the genetically modern humans that they are.

there's a clear cluster of modern human skulls from Hofmeyr in Africa to Lagoa Santa in Brazil that fits the behavioral modern time horizon

A "horizon" that starts at ~40kya in Africa end ends at ~10kya in America? Hmmm... sounds just like an early human migration theory I know.

And what did you expect to see? An African archaic?

"Everywhere", not just the same place.

And what would you expect if Africans descended from it and then non-Africans descended from Africans?

In that scenario I would expect modern Africans and modern non-Africans to be roughly equidistant from it... they'd have the same branch length to it so there's be no discernable "chimp" shift either way.

German Dziebel said...

@Tobus

"I think the Yoruba, San and Massai represented in HapMap would disagree with that statement, being the genetically modern humans that they are."

I put "genetically modern humans" in quotation marks to refer to your misnomer. In fact you wanted to say "anatomically modern humans" which is a set of remains dated between 200,000 and 90,000 years in Africa. We don't have any DNA from them.

"A "horizon" that starts at ~40kya in Africa end ends at ~10kya in America? Hmmm... sounds just like an early human migration theory I know."

Your typical mistake: it's attestation, not derivation. We were lucky to find a 36,000 year old African skull and a 12,000 year old Amerindian skull. But the important point is that they form a cluster and Hofmeyr shows increased affinities with Eurasia and not with "anatomically modern skulls" in Africa. If African genetic lineages are older than 50,000 years old, then they must have been absorbed from "archaics."

"In that scenario I would expect modern Africans and modern non-Africans to be roughly equidistant from it... they'd have the same branch length to it so there's be no discernable "chimp" shift either way."

Well, the shift exists now, which supports archaic introgression in Africa. And a significant one. And since all humans, including modern Africans, are closer to Eurasian hominins an extra-African origin should be the first option to consider.

terryt said...

"A "horizon" that starts at ~40kya in Africa end ends at ~10kya in America? Hmmm... sounds just like an early human migration theory I know".

That wouldn't be German's UFO theory for the settlement of America would it?

"And since all humans, including modern Africans, are closer to Eurasian hominins an extra-African origin should be the first option to consider".

I'm prepared to accept that to some extent. After all we do have evidence of ancient Eurasian entry into Africa (a Dienekes post of some time ago) and evidence of some level of introgression from an older 'species' in Africa. But there is a huge chasm between those two aspects and the 'out of America' you propose.

Tobus said...

@German:
I put "genetically modern humans" in quotation marks to refer to your misnomer. In fact you wanted to say "anatomically modern humans..

No, I intentionally used "genetically" to refer to genetic lineages since the MCRA of modern humans. In genetic terms, "archaics" are populations that diverged before this point, "modern humans" are all those after it.

...which is a set of remains dated between 200,000 and 90,000 years in Africa

I think you'll find it's from 200,000ya to the present.

But the important point is that they form a cluster

What evidence do you have for Hofmeyr clustering with Luzia anyway? I can't find any evidence of this in any published paper - Hofmeyr clusters with ancient Europeans, Luzia with Melanesians/Australians.... is this another of your bend-the-truth-and-hope-no one-notices statements?

Hofmeyr shows increased affinities with Eurasia and not with "anatomically modern skulls" in Africa.

Hofmeyr doesn't show affinity with anatomically modern Amerindian skulls, nor anatomically modern European skulls either.

If African genetic lineages are older than 50,000 years old, then they must have been absorbed from "archaics."

I'm intrigued by your use of the word "must" here - surely you mean "might"? For instance: Hofmeyer *might* be representative of a phenotype that existed long before 50kya. Modern African skull morphology *might* have developed in situ sometime after the Hofmeyer sample. Hofmeyer *might* be only one of a wider range of modern human skulls at 38kya, etc., etc. These are all other possibilities for variation in ancient/modern skull morphology in Africa that make your "must" seem a little premature.


Dobba Makale said...

@Tobus "I'm intrigued by your use of the word "must" here - surely you mean "might"? For instance: Hofmeyer *might* be representative of a phenotype that existed long before 50kya. Modern African skull morphology *might* have developed in situ sometime after the Hofmeyer sample. Hofmeyer *might* be only one of a wider range of modern human skulls at 38kya, etc., etc. These are all other possibilities for variation in ancient/modern skull morphology in Africa that make your "must" seem a little premature."

So the earliest Homo sapiens don't look like Caucasian, Mongoloid and Negroid right? I think they also don't have darker skin as what the majority said.

Tobus said...

@Dobba:
So the earliest Homo sapiens don't look like Caucasian, Mongoloid and Negroid right?

Well they didn't have the exact same skull, but it's relative - they certainly looked a lot more like modern humans than Neanderthals for instance.

I think they also don't have darker skin as what the majority said.

That's very unlikely. The alleles causing lighter skin in modern Europeans/East Asians are known to have only arisen relatively recently, within the last 20,000 years. So if ancient sapiens had light skin it was due to mutations that no longer exist. Light skin has been positively associated with low UV environments, with pigmentation-related genes (like MC1R) being under extremely strong functional constraint in the tropics throughout the world... so there's no logical reason to expect ancient populations in Africa would be an exception.

Ultimately, without a photo or some other physical evidence it's impossible to know for sure, but with no evidence to suggest light-skin and lots of reasons to doubt it, the only reason to propose such a notion is a preconceived aversion to dark-skinned ancestors (or a preference for light-skinned ones)... with what we know at this point in time, dark-skinned ancestors is really the only reasonable assumption.

Dobba Makale said...

@Tobus "Well they didn't have the exact same skull, but it's relative - they certainly looked a lot more like modern humans than Neanderthals for instance."

In your opinion, is it rational to conclude that the first or earliest Homo sapiens have Negroid physical appearance and certainly are dark-skinned?

Tobus said...

@Dobba:
In your opinion, is it rational to conclude that the first or earliest Homo sapiens have Negroid physical appearance and certainly are dark-skinned?

I think they certainly had dark skin, but probably not "Negroid physical appearance" - the oldest skulls don't have the features that typically distinguish "Negroid" skulls (nor those that distinguish "Caucasian" or "Mongoloid"). They'd certainly be classed as their own "-oid" race if any were found wandering the streets today. There's an artist's impression based on the Idaltu skull (160kya) here - make what you will of that (looks most like a robust Melanesian to me).

Tobus said...
This comment has been removed by the author.