There is reason to believe that Australo-Melanesians used to occupy a much larger area than they do today. Let’s define them by their genetic affinity to that odd genetic trace in Amazonian Amerindians: those related include Papuans, Aboriginal Australians, Andaman Islanders ( closest), and Negrito groups in Southeast Asia and the Philippines.
Skeletal evidence says that they used to occupy all of Southeast Asia (probably at least as far north as southern China, fairly recently), and have been largely replaced by people from further north over the past few thousand years. Same is the case for the Philippines & most of Indonesia.
In fact, even further north than that: a skeleton from Tianyuan cave, not far from Beijing, shows the same genetic trace. From about 40,000 years ago. So it’s more plausible that there was a potential source population in a more geographically felicitous area ( for settling the New World) at the proper time ( ~20k BC).
Looking at recombination (roloff) should tell us approximately how long ago the admixture occurred. I would hope to see rare mtDNA haplotypes in those Amazonian Indians – Y chromosomes, considerably less likely. I would expect to see a few alleles from the Australo-Melanesians favored by selection in South America. By analogy with what we’ve seen with archaic admixture, stuff like HLA would seem likely.
West Hunter 
On the subject of South China: years ago I read that the y chromosomes of southern Chinese were little different from those of the northern Chinese, but that the mitochondrial DNA was markedly different. True?
On the subject of the Abos: they may have been replaced elsewhere, but they were numerous enough, and tough enough, to repel any Polynesians who came visiting Australia. Maybe the Barrier Reef was a help too.
What I don’t understand is how all of the Americas could have been populated by Australo-Melanesians (population expansion in virgin territory should have been quick, so I’d expect them to have been everywhere), and then been replaced so thoroughly, leaving behind just the tiniest hint of themselves in Amazonia (of all places). The Neanderthals and Denisovans had a much bigger genetic impact on the newcomers, and they weren’t even modern humans. The Indians had a bigger genetic impact on the whites, despite the technological difference and new diseases. How could replacement have been so complete?
Isn’t the suggestion that the Injun invaders had picked up traces of Melanesian before they left Asia?
Since it’s in South America, but not North America, I doubt it.
Do you doubt that that is the suggestion? Or do you accept that that is the suggestion but deem it unlikely to be true?
I doubt if it is true. And my informants ( also my reading of some recent papers) indicate that people researching suspect that the Australo-Melanesians came first.
Did they, by golly? What supportive evidence is required: some skeletons and ancient DNA?
I suppose the matter of Kennewick Man rather suggests that doing science on any skeleton that turns up may be prohibited.
I am unclear about the results for the Onge-like admixture in Native Americans. In Raghavan 2015 they claim that an Aleutian Islander and some Athabaskans also have this signal, while the two Skoglund papers only mention Cree, Ojibwa, Algonquin plus the ancient Anzick sample for North American samples. Also isn’t it the case that in general North American Indians are not well sampled? I guess I am wondering how much confidence one should have in the observation that only certain Amazonians have the Onge-like ancestry.
The Science paper looked highly fallible to me. Not least, the idea that this was a recent admixture is just ridiculous.
Can we be sure of this? North America is pretty poorly sampled, thanks to identity politics.
The admixture is somethng like 1-2%, similar in amount to the amount of Neanderthal admixture in Eurasians.
Amazonia was good hunter-gatherer country in 18,000 BC: North America was not. Ice, tundra, taiga.
If we’re talking old Anglo settlers, pioneers in the US, Amerindians did not make a bigger genetic contribution.
But my understanding (I have not read the papers) is that it isn’t even all of Amazonia, just a few tribes. It seems strange to me that a little bubble of divergent ancestry could maintain its integrity over so many thousands of years without either diffusing into the surrounding populations or, alternatively, being completely swamped. Over that much time I would expect either one or the other, not some unstable middle ground. (This is somewhat analogous to the way that I would expect Jesus to either have millions of descendants today, or else none at all, but certainly — pace Dan Brown — not just one!)
OK, that makes more sense. The impression I had gotten was that the Surui and Karitiana were all alone in a sea of white.
Don’t Polynesians have substantial Melanesian ancestry? Is it possible that the Melanesian traces in South America are the result of Polynesian admixture?
Polynesians do have some Melanesian ancestry, but if they were the source, they’d show the strongest shared signal with those Amazonian Indians. But they don’t: it’s strongest in the Andaman islanders, still stronger than Polynesians in Australians and Papuans.
Here’s an example that may help understand how you can get to 2% quite easily; Magdalenian Upper Paleolithic Europeans have left very little trace in Western Europeans of Spain, today, possibly less.
It’s not too difficult to see how that can happen with a few repeated waves. 0.25^3 = about 2%. Even three waves with survival of around 25% can do that.
In the actual example of European history; we have approximately
WHG replacing Magdalenians by about 75%; 25% Magdalenian.
Early European Farmers replacing WHG by about 75%, 6.25% Magdalenian.
Yamnaya replacing Early European Farmers in UK by 50%, 3% Magdalenian, or in Spain by 30%, 4% Magdalenian.
If you assume the replacements are 80% in the first two cases, then UK 2% Magdalenian, Spain 2.8% Magdalenian.
The fact that these turnovers of approx 70% seem to have happened in Ice Age Europe at least three times, among hunter gatherers (Aurignacian->Gravettian->Magdalenian->WHG) makes it quite likely they were frequent between HG populations. See Fu et al 2016. You don’t need total replacement with one movement (though that can happen); a few layers of incomplete replacement 70:30 or 80:20 will easily get down to 2%.
The Neanderthals and Denisovans were in an opportune point to enter the Out of African populations and get into all possible descendants (respectively to Eurasia and Oceania). Later HS groups were not in the same position.
You have o take into account that part of what replaced what actually was created from previous admixtures. For instance, Yamnaya brought a good chunk WHG with it. And current day Europeans are modeled as Middle-Neolithic farmers + Yamnaya + extra shot WHG:
That could be he reason why, if you run stats, some Magdalenians look roughly in the same proportion as ANE in NW-Europeans.
https://www.nature.com/nature/journal/v534/n7606/fig_tab/nature17993_ST6.html
In terms of relatedness, yes, the Magdalenians are probably about as related to recent Europeans as the late ANE. But that’s not in contradiction with the models suggesting that they have almost no independent contribution to present day people. They’re related to recent Europeans because they were replaced by people who were fairly close relatives (in the grand scheme of drift since out of Africa).
Lazaridis 2014 estimated Europeans as part WHG, EEF and ANE. WHG came up as roughly 30-45%. Furthermore, check the D-stats where GoyetQ116 actually stands out (|Z|=8) compared to hunter-gatherers which were more are more generally related to Europeans (|Z| ~ 5.5). Magdalenians are basically 2/3 Goyet116, a point which also goes to show how some ancestry can make surprising come backs.
How did they get to the Americas? Northbound along the edge of the ice? Surely they can’t have island-hopped across the Pacific without leaving traces?
Greg doesn’t mention it but according to the talks Tianyuan had an affinity to GoyetQ2-116 – an early European hunter-gatherer that clearly was in the same clade as most European hunter-gatherers – that was as great as it’s affinity to East-Asians. The Solutreans most likely were the predecessors of the Magdalenians, while the latter are basically a continuation of GoyetQ2-116 according to their genomes.
Hello Solutrean hypothesis?
DISCLAIMER: Tongue in cheek.
Luzia
Almost complete population replacements happened a number ot times in various places in the ancient world. It is a reality that doesn’t fit with modern human behavior. A super hybrid of Stalin and Hiltler with luck on his side couldn’t replace the population of neighboring countries with his own kind.
But it happened with a fair frequency in the good old days.
The tale of 20th century Europe is of a large expansion of the Slavs at the expense of the Germans. After Hitler’s war a chunk of Eastern Germany was cleared of Germans and settled by Poles; the Sudeten Germans were expelled from Bohemia and Moravia. Germans were chased from, or exterminated in, parts of Eastern Europe and the USSR where their ancestors had lived for centuries.
After the Kaiser’s war, Greeks were ditto’d out of Anatolia. And during that war the Turks holocausted Armenians.
The indigenous Injuns were replaced by Europeans (and Africans) in most of North America in modern times.
Meantime a dramatic population replacement is (I guess) underway in Sweden, and perhaps in Belgium, Germany, and France. In Britain too, maybe – or at least in England.
“It is a reality that doesn’t fit with modern human behavior” seems to me to be absurdly smug.
That was part of Hitler’s goal:Lebensraum. Stalin didn’t even have a goal of replacing the population of his own country with his kind. I don’t see an Austro-Georgian hybrid people going too far.
“I would hope to see rare mtDNA haplotypes in those Amazonian Indians.”
Nope. Nothing special there.
We would have to look hard, sequence every member of certain tribes. hasn’t been done.
There’s a linguistic theory that posits the Japanese language is a hybrid, perhaps a sort of creole, between some sort of proto-Altaic northern Asian stock and something like the Austronesian languages represented much further south in the continent. Given the relatively fringe location of the island to the continent, I suppose the idea of a partial hold-over like this might be plausible. It seems evident to one who investigates the connections that Japanese is likely some sort of relation to Korean but almost impossible to demonstrate clearly. The Korean peninsula itself might be another fringe location. Might there be a South Asian linguistic connection for the Ainu?