As I have argued before, this makes very little sense. Why would a mobile species that is beginning to populate the world form a unity until so late. Indeed, we have arrival of modern humans in both Europe and East Asia long before the ~22.5kya date, and the divergence of these humans into the two major Eurasian races starts already in the Paleolithic. The idea that the ancestors of modern Caucasoids and Mongoloids formed a unity as late as ~22.5kya is a fantasy.
What gives then? The problem arises from the failure to appreciate intra-African variation. The temporal gap between the demographic expansion of Homo sapiens and Eurasians is not due to an early Out of Africa event followed by a period of stasis.
Rather, the Out-of-Africa event was one side of a coin that included a related Deeper-into-Africa event. The fourty thousand year gap is, in part, due to population structure in Africa itself, with Eurasians being late descendants of an East African subpopulation and modern Africans being an admixture of East Africans and the pre-existing populations of the continent, whose least admixed modern representatives are the Khoi-San and Pygmies.
It makes no sense that Eurasians left Africa and then "stayed as one" for forty thousand years, just as they had the Earth's largest landmass to populate and the record says that they did populate it. Rather, the forty thousand year gap should be split into "African" and "Eurasian" components, with the former representing African population structure that later broke down, forming the present-day mosaic of African peoples, and the latter representing the early period of Eurasian unity during the early stages of our species' Out of Africa adventures.
It is telling that the authors consider a model in which the ancestors of modern humans replaced archaic humans in Eurasians, but it does not dawn on them at all, that these same ancestors may have replaced or absorbed archaic humans (or early modern ones) in Africa itself.
PLoS ONE doi: 10.1371/journal.pone.0010284
Formulating a Historical and Demographic Model of Recent Human Evolution Based on Resequencing Data from Noncoding Regions
Guillaume Laval et al.
Abstract
Background
Estimating the historical and demographic parameters that characterize modern human populations is a fundamental part of reconstructing the recent history of our species. In addition, the development of a model of human evolution that can best explain neutral genetic diversity is required to identify confidently regions of the human genome that have been targeted by natural selection.
Methodology/Principal Findings
We have resequenced 20 independent noncoding autosomal regions dispersed throughout the genome in 213 individuals from different continental populations, corresponding to a total of ~6 Mb of diploid resequencing data. We used these data to explore and co-estimate an extensive range of historical and demographic parameters with a statistical framework that combines the evaluation of multiple models of human evolution via a best-fit approach, followed by an Approximate Bayesian Computation (ABC) analysis. From a methodological standpoint, evaluating the accuracy of the parameter co-estimation allowed us to identify the most accurate set of statistics to be used for the estimation of each of the different historical and demographic parameters characterizing recent human evolution.
Conclusions/Significance
Our results support a model in which modern humans left Africa through a single major dispersal event occurring ~60,000 years ago, corresponding to a drastic reduction of ~5 times the effective population size of the ancestral African population of ~13,800 individuals. Subsequently, the ancestors of modern Europeans and East Asians diverged much later, ~22,500 years ago, from the population of ancestral migrants. This late diversification of Eurasians after the African exodus points to the occurrence of a long maturation phase in which the ancestral Eurasian population was not yet diversified.
Link
PLoS ONE doi: 10.1371/journal.pone.0010284
Formulating a Historical and Demographic Model of Recent Human Evolution Based on Resequencing Data from Noncoding Regions
Guillaume Laval et al.
Abstract
Background
Estimating the historical and demographic parameters that characterize modern human populations is a fundamental part of reconstructing the recent history of our species. In addition, the development of a model of human evolution that can best explain neutral genetic diversity is required to identify confidently regions of the human genome that have been targeted by natural selection.
Methodology/Principal Findings
We have resequenced 20 independent noncoding autosomal regions dispersed throughout the genome in 213 individuals from different continental populations, corresponding to a total of ~6 Mb of diploid resequencing data. We used these data to explore and co-estimate an extensive range of historical and demographic parameters with a statistical framework that combines the evaluation of multiple models of human evolution via a best-fit approach, followed by an Approximate Bayesian Computation (ABC) analysis. From a methodological standpoint, evaluating the accuracy of the parameter co-estimation allowed us to identify the most accurate set of statistics to be used for the estimation of each of the different historical and demographic parameters characterizing recent human evolution.
Conclusions/Significance
Our results support a model in which modern humans left Africa through a single major dispersal event occurring ~60,000 years ago, corresponding to a drastic reduction of ~5 times the effective population size of the ancestral African population of ~13,800 individuals. Subsequently, the ancestors of modern Europeans and East Asians diverged much later, ~22,500 years ago, from the population of ancestral migrants. This late diversification of Eurasians after the African exodus points to the occurrence of a long maturation phase in which the ancestral Eurasian population was not yet diversified.
Link
26 comments:
The dates are obviously nonsense, especially once you also include the 20,000 or so years of hiatus in Beringia, etc.
I can't follow all the statistics they did and the underlying assumptions, but the fact that the dates are all so off doesn't bode well for whatever clock or population size assumptions they made, or the state of the field in general.
Clearly, after ~45,000 years ago there was continued exchange between northern India/Pakistan, the plains, and Europe, probably until about 25,000 years ago. But that would have had little effect on continuing eastward exchange, which also would have been comparatively more inhibited due to geographical factors.
Razib Khan too is highly skeptical (and so do I) of a common Eurasian population for such a long time (40,000 years!). He also thinks that the authors of the paper probably aren't convinced of it either. This is what he writes on this matter in his thread about the same paper:
"I’ll stipulate that I haven’t dug deep into the statistics, nor would I really comprehend all the details if I did spend a weekend on it. But I’m rather skeptical of the 40,000 year period of a common Eurasian population. Reading the text where they discuss this finding it seems clear that it was surprising to the authors, and I’m not sure how convinced they are about it either."
http://blogs.discovermagazine.com/gnxp/2010/04/nearly-100-out-of-africa-in-the-past-100000-years/
I think that these dates are reliable and it isn't the first time that scholars write this. An average date of separation between Europeans (only Danes really) and East Asians is reliable if we consider the apportion of NO and P(Q/R) Ydna haplogroups, mixed with previous "European" haplogroups and previous mtDNA. The authors of the paper have calculated the gene flow from Central Asia with Europe and Eastern Asia and the data are these.
By my point of view this demonstrates that Haplogroup R1b1/R1b1b2 hasn't come from Central Asia a few thousands of years ago like many pretend, but like I have always thought at least before the Younger Dryas.
I largely agree with your criticism, Dienekes. The results are very much unbelievable and you're also surely right in the OoA being largely "a side of a coin" with another side being the L3/E expansion in Africa.
However I must say that I have seen many other such unbelievable theoretical exercises before. This one is not really worse than other stuff we're used to.
Not sure how good it may be, because the results and modeling are rather contentious, but I toyed a bit with simple proportions and the best correction I can make is to multiply the results by a factor of 2.2, what gives us:
- Eurasian divergence: 50 Ka
- OoA: 132 Ka
Considering that, following the genetic track, right until the beginning of the colonization of West Eurasia, Tropical Asia does not behave yet as several regions but rather as a single fluid one such region, this result could make sense, if you can accept an early OoA (consider an error margin too).
Just a tentative correction anyhow. I'm not going to defend this.
I agree that 22,500 years does seem a little recent for the divergence of Eurasian populations. However it seems that surviving European haplogroups may be no older than this date.
Another problem, though, is that migration from the 'main' population (whatever and where-ever that was) into a region already occupied by members of this main population who had moved in earlier would lead to the formation of a hybrid population. The resulting mix of genes would distort the apparent separation date. The mix would shorten or lengthen the date depending on the relative proportions of the two, or more, contributing populations, and their length of separation from the main population and from each other.
With that in mind I think it might be instructive to turn to the origin of this main population, Africa. Whether they came via the Bab al Mandab or the Levant surely it is most unlikely that the OoA population contained a completely representative sample of the whole African population of the time.
If we confine our perspective for now to just the mtDNA we see that just two subsets (M and N) of a wider subset (L3), which is in turn part of a wider subset etc., emerged from Africa. We might be on more convincing ground when we check out the Y-chromosome. But even here it's quite possible that a single haplogroup (CDEF) of a wider subset (B) made it out. But possibly we have 50% of the contemporary African Y-haps emerging (C, D and F as against A, B and E).
The question does arise, of course, as to whether the ex-Africa Y-haps and mtDNA emerged together. But however we look at the evidence we are left with what seems to be just a small group of people emerging from Africa. And this paper shows the population then paused, and was presumably confined to a small region for some time. Yet some of us still manage to believe that when it expanded this small group of people, after being subject to all this founder effect, selection and diminishing genetic variation, contained all the genes that have given rise to our contemporary human geographic variation. They claim in fact that we 'are looking at tablespoons of the same puree, so all pumpkin puree ones are orange, while the lentils puree ones look brown, regardless on whether pumpkin was also an ingredient in the puree'. Is this really likely? Much of the geograhic variation we see today is surely at least partly the result of mutations since the OoA, if not the remnant of pre-OoA populations.
Returning to the subject of hybridism. If the OoA people had actually mixed with a group, or groups, who had emerged from Africa even earlier it would also distort the apparent separation date of the whole OoA scenario.
Such skepticism. I suppose it goes against all the commonly accepted beliefs of most people. It pays to keep an open mind as that is what science works on, not closed shut stubborn ones as I have read so far, but you are not scientists.
Gioiello's hanging onto his R1b beliefs. Good for you. It seems everyone else doing the research have moved on leaving you behind. The subclade of R1b that is important to him, is not a few thousands of years old as you stated glibly but more like 5,000 to 6,000 years old. You forget that a lot of Europe was an uninhabited ice wasteland for many thousands of years, and only became habitable again after the start of the Holocene period. All that we have are some Ice Age remains of humans who lived in Europe but did not look like any Europeans living today or any other race for that matter like that antique Russian or the antique Romanian. So where are the European races? Hiding in the Middle East I suppose.
Do I accept the findings of the study. Not really but I am not rejecting it because of my biases. All I say to you is show me all those European looking Europeans from more than 20,000 years ago. Even the studies on ancient remains like the Italian cave remains, bone splinters really, have produced dubious results but I have yet to see a representation of that human. Even Cheddar Man was something horrific to behold, and not very European like and he was around 10,000 years old.
Rather than carp like old women, produce the evidence i.e the bones in Europe, the Middle East, Africa, South Asia and East Asia and prove your case that races existed more than 20,000 years ago. All you can do is look to Australia but then, they are archaic and don't count right?
And this paper shows the population then paused, and was presumably confined to a small region for some time.
And this, unfortunately for the study, is exactly what we know with certainty did not happen.
We know that south-central Asia, and later also SE Asia, were places where AMHs could and did multiply swiftly, with huge stars of haplogroups forming that went everywhere geographically possible.
We also know with absolute certainty that by ~50,000 years ago they became ready to leave the shielded tropics and vicinity for the harsh conditions of higher latitudes - both east and west. And the y-haplogroup subset that made it west could not be more different from the one that made it east if the Himalayas were as north-south divide.
Statistical studies like these, when done properly, account for continued low-rate genetic exchange. We know such thing happened in historic times between eastern peoples and western Asia and Europe - in smaller amounts the farther west you go - so it very likely happened in the 40,000 years before, too, except at a lower rate, given smaller population densities and lack of equipment to move swiftly.
We also know that reverse west-to-east flows were relatively rare and had little impact beyond central Asia. And the mt-DNA and y-haplogroup subsets in eastern Asia and the Americas show that there was also little continued gene flow from south-central Asia to those regions.
The point is that all those influences on autosomal DNA should be taken care of in a study like this and should not pollute the time estimates.
50,000 years ago was, by all we know, the last possible date for the first major separation between European and north-east Asian populations from their south-central-Asian progenitors. Europe likely had continued tighter contact with populations in the plains and with northern Pakistan and India, while Eastern Asia had some continued contact with south-east Asian people. But south-central and south-east Asia were the largest population of them all, so it makes little sense that whatever filtered in from either side would have been able to cross that region and mix, effectively.
To fit the date of 25,000 years, you would need to postulate that pretty much all humans in the far west, far northeast, and southeast died out completely, to be replaced by newly advancing populations from ~India, just in time before LGM, and completely ignoring all the timing studies on Beringian populations.
As I said before, it makes no sense, and the timing is off, we all know that. Like Maju I would also come to the conclusion that the timing is off by about a factor of 2, except that I am not convinced of such an early south-central Asian populating of AMHs for the resulting >100,000 out-of-Africa date (although clearly a possibility, for now). So perhaps, the authors completely underestimated the huge population size differences (a factor of hundred or so) in these various regions mentioned above.
Ponto writes, the first time he calls me by name: "Gioiello's hanging onto his R1b beliefs. Good for you".
I think having demonstrated, in my thousands of posts I wrote in my bad English, what I believe.
I am waiting hopeful for the aDNA tests, which will solve every question. I can't now list all my argumentations. You can see them on "Genealogy-dna", "forums-dna", here, on Worldsfamilies, Rokus' blog, etc.
I have yet adfirmed that Maltese are at least for 90% genetically Italians, even though you probably don't like it.
"so it very likely happened in the 40,000 years before, too, except at a lower rate, given smaller population densities"
But those 'smaller population densities' would mean that small numbers of immigrants could have a large effect.
But those 'smaller population densities' would mean that small numbers of immigrants could have a large effect.
No, not if subsistence of the migrating groups was marginal, and if they had to travel 10,000 kilometers in an increasingly and quickly worsening climate. Most of them likely never finished the journey, or were not received with open arms to spread their genes.
And even with a low density, the well-adapted total population size of the rich hunting grounds between the northern German plains and the Ukraine was substantial and unlikely to be completely overwhelmed by newcomers from milder climates of the southeast.
I agree there would have been population pressure in India and migrations took place, but there is no easy exit out of India, especially without pack animals, and during that climate.
Remember, this paper basically demands a complete replacement of the existing European population by 22,500.
Is there any know archaeological evidence of mass migrations and replacements during the Gravettian? I'd say, quite the opposite. And also the ensuing Magdalanien seems 100% home-made.
So what is producing the data?
I think what you have is something like this:
(1) A small subset of modern humans from the mtDNA L3 lineage associated with East Africa leaves Africa ca. 65,000 years ago and spread throughout Africa and Eurasia including Australia and New Guinea.
(2) Modern humans retreat from Northern Eurasia in the face of the LGM.
(3) The hunter-gatherers in Europe (and probably in other populations) prior to last glacial maximum differ greatly genetically from the populations that expand in connnection with the expansion of herding and farming. Only a small subset of the prior Out-of-Africa population lineages are included in the Neolithic and immediately pre-Neolithic population expansion. Most of the first Out-of-Africa wave has a greatly diminished share of the Eurasian gene pool.
(4) The populations that migrate out of centers where the neolithic revolution have taken place (and perhaps immediately before them as proto-agriculture or the retreat of the ice pack after the LGM) substantially (80%+) replace prior populations (just how many waves are involved in the Holocene population booms doesn't matter).
(5) In any given continental region, the predominance of lineages probably had common ancestry ca. 22,500 years ago (including Africa, where there is evidence that there was a Neolithic population explosion that overwhelmed prior hunter-gather populations genetically just as on other continents).
The evidence and analysis showing that the Eastern and Western Eurasian components were common is weak (and the implication is arguably even sloppy conclusion writing), but not one disputes the original Out of Africa dispersal event left them closer to each other than to African lineages, and regional explosions of subpopulations within each region don't look that different from a single Eurasian subpopulation explosion in the data.
I also agree with Dienekes that the amount of initial population differentiation and structure in the Out of African group as of 65,000 years ago is underestimated in their model. We have to have several subdivisions of M, N and R on the mtDNA side, and of K on the Y-DNA side by the time humans reach Australia and New Guinea around 45,000 years ago. Since there is very little evidence of mtDNA M, N and R haplogroups and Y-DNA K (or for that matter Y-DNA IJK or Y-DNA F haplogroups) except through relatively recent back migration in Africa, and very little evidence of mtDNA L haplogroups, or Y-DNA A, B or E haplogroups beyond the Near East, the time frame for the major lineage divisions of Eurasia have to be far older than 22,500 years ago.
I largely agree with your summary Andrew. And I especially believe your comment '(2) Modern humans retreat from Northern Eurasia in the face of the LGM' is too often ignored. I stongly suspect that by then humans had spread across Central Eurasia as far as Japan, and perhaps even down the eastern coastline. It's difficult to argue effectively that Y-hap C reached Australia and Japan via India. And mtDNA N also sustains much the same difficulty.
"the amount of initial population differentiation and structure in the Out of African group as of 65,000 years ago is underestimated in their model".
I can't see how the OoA group was anything other than extremely limited genetically.
"We have to have several subdivisions of M, N and R on the mtDNA side, and of K on the Y-DNA side by the time humans reach Australia and New Guinea around 45,000 years ago".
A problem. Most of the Y-hap K seems to diversify only once it gets beyond Wallacea, not before. And just small sub-samples of mtDNA M, N and R reached Australia. Again, the relevant haplogroups probably differentiated once they reached there. So another explanation is needed. You can argue bottlenecks etc., but once you start doing that you can effectively claim almost any scenario.
"Since there is very little evidence of mtDNA M, N and R haplogroups and Y-DNA K (or for that matter Y-DNA IJK or Y-DNA F haplogroups) except through relatively recent back migration in Africa"
And that argues eloquently that all their diversity is post OoA. They didn't emerge fully differentiated.
"the time frame for the major lineage divisions of Eurasia have to be far older than 22,500 years ago".
We know that Y-hap R spread widely, as did mtDNA R. Presumably long before 22,500 years, but those haplogroups (and others) were almost certainly responsible for a large amount of hybridisation, which would skew the date. And your number 4 is also almost certainly a significant factor.
"No, not if subsistence of the migrating groups was marginal, and if they had to travel 10,000 kilometers in an increasingly and quickly worsening climate".
Again I mention Y-hap and mtDNA R. They certainly spread a long way.
I can't see how the OoA group was anything other than extremely limited genetically.
Today, two Khoisan from neighboring villages are likely to be autosomically more diverse than any random European from an Asian. I am sure even 10 people migrating out of Africa were way more diverse than anything left in Eurasia today. This of course also has made it difficult to assess unusual autosomal DNA stretches in Eurasia: are they ancient admixture? Likely not - likely they are just leftover remnants of the initially much wider diversity, and can likely be found in African populations, as long as you look hard enough.
Again I mention Y-hap and mtDNA R. They certainly spread a long way.
Regarding Y-haplogroup R, that migration and spread is not a problem in models where this actually was the largest haplogroup to reach Europe some time before 30,000 years ago.
A lot of the complications and contradictions result from completely arbitrary and unjustified assumptions and models that insist that haplogroups found today (at that level - like R and I) are somehow recent (i.e., post-LGM or even neolithic).
(2) Modern humans retreat from Northern Eurasia in the face of the LGM.
We know that did not happen. There were known pockets of AMHs in nowadays France away from the Mediterranean, possibly southern Germany, definitely the Czech republic and Serbia/Croatia, the Ukraine and parts of Russia, likely some of the -stan regions, and in East Asia all the way to Beringia as continuing populations before, during, and after LGM. By that time, people simply had figured out how to live under those conditions, as long as there were large mammals to hunt.
(3) The hunter-gatherers in Europe (and probably in other populations) prior to last glacial maximum differ greatly genetically from the populations that expand in connnection with the expansion of herding and farming.
I would not take a single, flawed paper like this as evidence for your "scenario." In fact, I still see no evidence whatsoever for a significant replacement of autosomal DNA in neolithic Europe.
(3) The hunter-gatherers in Europe (and probably in other populations) prior to last glacial maximum differ greatly genetically from the populations that expand in connnection with the expansion of herding and farming.
Do you think that the formers were negroid and the latters caucasoid?
"two Khoisan from neighboring villages are likely to be autosomically more diverse than any random European from an Asian".
Probably so today, but there has been a long period of mixing with immigrants from outside Southern Africa, especially the Bantu from Central West Africa. It's extremely doubtful that the region that supplied the original OoA was particularly genetically diverse.
"I am sure even 10 people migrating out of Africa were way more diverse than anything left in Eurasia today'.
Possibly. But only if they were selected from a fairly wide region.
"likely they are just leftover remnants of the initially much wider diversity, and can likely be found in African populations, as long as you look hard enough".
I doubt that very much.
"and in East Asia all the way to Beringia as continuing populations before, during, and after LGM".
I agree with that, but I'd be interested in anything Maju would care to add concerning the statement.
"I'd be interested in anything Maju would care to add concerning the statement".
After the first few comments after my own, I felt so disappointed with the level of the discussion that I decided not to get in it further (waste of energies). I even almost unsubscribed to the topic.
The only (or main) exception, the only one who's making sense is Eurologist.
(2) Modern humans retreat from Northern Eurasia in the face of the LGM.
We know that did not happen. There were known pockets of AMHs in nowadays France away from the Mediterranean, possibly southern Germany, definitely the Czech republic and Serbia/Croatia, the Ukraine and parts of Russia, likely some of the -stan regions, and in East Asia all the way to Beringia as continuing populations before, during, and after LGM. By that time, people simply had figured out how to live under those conditions, as long as there were large mammals to hunt.
(3) The hunter-gatherers in Europe (and probably in other populations) prior to last glacial maximum differ greatly genetically from the populations that expand in connnection with the expansion of herding and farming.
I would not take a single, flawed paper like this as evidence for your "scenario." In fact, I still see no evidence whatsoever for a significant replacement of autosomal DNA in neolithic Europe.
None of my conclusions are based on data from this paper. Regarding LGM retreat and replacement in Europe:
"Taking the long view, we can divide the prehistory of modern humans in Europe into five major establishing episodes: first, the pioneer colonisation of the Upper Palaeolithic itself an aspect of the dispersal of modern humans out of Africa; second, the Late Glacial re-colonisation of much of the continent from southern refugia after the Last Glacial Maximum (LGM); third, the postglacial re-colonization by Mesolithic groups of deserted areas after the end of the Younger Dryas (marking the end of the Pleistocene and the beginning of the Holocene); fourth, fresh dispersals of Near Easterners with an incipient Neolithic package; and fifth, small-scale migrations along continent-wide economic exchange networks from the Copper Age onward," from "The Archaeogenetics of Europe", Soares, et al., Current Biology (2010).
In Northeat Eurasia, "the archaeological record in Siberia . . . indicates a near abandonment of northeast Siberia at the onset of the last glacial cycle, and its recolonization by population expansion following the LGM." "The Human Genetic History of the Americas: The Final Frontier", O'Rourke and Raff, Current Biology (2010) citing Goebel, T., "Pleistocene human colonization of Siberia and peopling of the Americas: an ecological approach." Evol. Anthropol. 8, 208-227 (1999) and Goebel, T., Waters, M.R., and O'Rourke, D.H., "The Late Pleistocene dispersal of modern humans in the Americas." Science 319, 1497-1502 (2008)
Re the genetic differences between hunter-gatherers and current populations in Europe see, e.g., "A Predominantly Neolithic Origin for European Paternal Lineages," Balaresque, et al., PLoS Biology (2010); "Genetic discontinuity between local hunter-gatherers and central Europe's first farmers," Bramanti, et al., Science (2009); Haak W et al., "Ancient DNA from the first European farmers in 7500-year-old Neolithic sites." Science
(2005); Rougier, et al., "Peştera cu Oase 2 and the cranial morphology of early modern Europeans" PNAS (2007).
(3) The hunter-gatherers in Europe (and probably in other populations) prior to last glacial maximum differ greatly genetically from the populations that expand in connnection with the expansion of herding and farming.
Do you think that the formers were negroid and the latters caucasoid?
I think that they had predominantly different Y-DNA lineages and mtDNA lineages and had an easily visibly different physical appearance from the newcomers from the Near East.
I don't think that the terms "negroid" or "caucasoid" are neither well defined nor consistently defined now, and are even more poorly fit to describe the predominant pre-LGM populations of Europe.
The reconstruction of the Peştera cu Oase, Romania skull is probably the closest insight we have into what those individuals looked like, although reconstructions are limited in what they can do (particularly in skin color).
If I had to pick one population of people that looks most like the Peştera cu Oase reconstruction, I'd say ancient Egyptians who aren't a particularly good fit to either your typical West African or your typical Western European archeotype (groups of people I am substituting for negroid and caucasoid since they are often used as archetypes for those terms).
There were known pockets of AMHs in nowadays France away from the Mediterranean, possibly southern Germany, definitely the Czech republic and Serbia/Croatia, the Ukraine and parts of Russia, likely some of the -stan regions,
Probably, lived quite near the LGM line, but not beyond it on a semi-permanent basis in very low numbers, and this is a pretty close fit to the region you describe.
A retreat likewise doesn't have to be 100% to exist. There are a few Berbers in the middle of the Sahara now, but it is entirely correct to say that there has been a retreat from the Sahara of human populations relative to the more humid period in the Holocene when it was a center of domestication, that tracks increasing aridity. A dramatic population decline is still a retreat.
all the way to Beringia as continuing populations before, during, and after LGM.
Ancient DNA makes clear that there is a major discontinuity between the LGM era populations of Northern Siberia and Arctic North America and the current populations there. The Paleoeskimos are largely not direct ancestors of the modern Inuits and North Siberians, with a handful of possible exceptions like the small Ket population of North Siberia which has strong linguistic and genetic affinities with the Na-Dene.
What we "know" is also quite qualified. The evidence isn't unequivocal on whether the population that ultimately migrated to the Americas did so pre- or post-LGM, and per O'Rourke cited in an earlier comment, "despite the fact that much of interior Beringia remains in contemporary Alaska and northeast Siberia, no archaeological evidence of this population in residence has been found."
At any rate, the climate in the Beringia area would be heavily influenced by ocean currents producing differences from the climate on either side of it. See, e.g., Alfimov and Berman, "Beringian climate during the Late Pleistocene and Holocene" Quaternary Science Reviews (2001) and the exact dates of human habitation there are unclear:
"We do not yet know when people first reached Beringia and settled there permanently, but it was the emergence of the Bering Land Bridge that enabled them to reach the North American continent. The earliest widespread, indisputable evidence of human occupation is dated to the closing millennia of the last glacial cycle, as early as 14,000 years ago in western Beringia and 12,000 years in the eastern sector. Evidence from the Bluefish Caves, in northern Yukon, suggests that people may have lived there during the height of the last glaciation, around 24,000 years ago, but no other human habitation sites of this age have yet been discovered elsewhere in Beringia. Hints of even earlier human presence, back to 40,000 years ago, have been reported from Old Crow Basin, and also in northern Yukon, hut these hints depend upon interpretation of redeposited mammoth bones rather than undisturbed archaeological deposits. Much more archaeological work will be needed to reveal a more complete picture of human occupation in Beringia." Richard E. Morlan, Canadian Museum of Civilization, December, 1996
"I don't think that the terms "negroid" or "caucasoid" are neither well defined nor consistently defined now"
Should read: "I think that the terms . . ."
I also think that I should be a more careful typist, but can't seem to find funding for a blog comment copy editor.
"Probably, lived quite near the LGM line"
Probaby or surely? There's an archaeological record to tell us about that. The ice sheet line at the LGM only reached as far south as central England by the Atlantic, also Baltic Germany nearly all Poland and Belarus (the southernmost reaches more or or less) and then head in NE direction through Russia.
I have read somewhere that permafrost reached as far south as Budapest (Beijing in Asia) but this is not an absolute barrier but rather an indicator of tundra climate, which can still be exploited by hunter-gatherers preying on reindeer and fish, for example.
The SW Atlantic was perfectly inhabitable (oceanic steppe) and the Franco-Cantabrian region was in fact the main 'refugium' and the most densely populated region of Europe by all records throughout all the Upper Paleolithic Age. Particular attention should be given in this context to the Dordogne basin, which had very high density even for the FC region's standards, supporting maybe four times the population of other areas within the region.
In the East people lived in Ukraine and the Don basin. We know they also lived in Mediterranean regions from Dalmatia to Spain but these were not really dense. And we know that some pockets of Central Europe, like the already mentioned Moravia, which kept forested patches through the LGM, were still inhabited even in the depths of the LGM.
Some cases are known of course to have lived very close to the ice sheet line but this does not seem to be the general pattern. In any case, even in the worst of the LGM, most of Central Europe was not covered in ice, though was largely permafrosted, I presume.
The archaeological record is pretty thin (these are people who didn't have fixed villages and lived in quite small groups) and the margin of error in dating methods for LGM artifacts is less close than one might hope (the dating of the LGM itself varies in the literature by a couple thousand years from paper to paper). Even in the more recent linear pottery finds, the C-14 dating from multiple sites has a 95% confidence interval of several hundred years.
When one is trying to appraise the distance of archeological traces from the LGM one has to make an approximation of where the glacial line was at a particular time and when the objects found date from. There are clues like data on animal and plant species found with artifacts, tool packages used, and imported materials, that can help one make good guesses on climate at the time the artifact (or human remains) were left, but it would be huris to exagerate the precision of that evidence.
The archaeological record in Europe is very good. It's not I who says that but experts also think that the density of research is good and rather homogeneous, allowing them to make pretty reasonable statistical estimates.
The knowledge of max. glacial lines is pretty good, even if there are many maps around that are not good enough - but this is different. I can assure you that Belgium, for instance, was never under the ice, though it surely had extremely cold periods with tundra conditions, when population was almost nil.
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