While it is close, this find is still consistent with a modern human migration through Southeast Asia made possible by the Toba eruption.
The timing of the first arrival of Homo sapiens in East Asia from Africa and the degree to which they interbred with or replaced local archaic populations is controversial. Previous discoveries from Tam Pà Ling cave (Laos) identified H. sapiens in Southeast Asia by at least 46 kyr. We report on a recently discovered frontal bone (TPL 6) and tibial fragment (TPL 7) found in the deepest layers of TPL.
Bayesian modeling of luminescence dating of sediments and U-series and combined U-series-ESR dating of mammalian teeth reveals a depositional sequence spanning ~86 kyr. TPL 6 confirms the presence of H. sapiens by 70 ± 3 kyr, and TPL 7 extends this range to 77 ± 9 kyr, supporting an early dispersal of H. sapiens into Southeast Asia. Geometric morphometric analyses of TPL 6 suggest descent from a gracile immigrant population rather than evolution from or admixture with local archaic populations.
Sarah E. Freidline, et al., "Early presence of Homo sapiens in Southeast Asia by 86–68 kyr at Tam Pà Ling, Northern Laos" 14 Nature Communications 3193 (June 13, 2023).
9 comments:
I know it is extremely unlikely that we'll ever see Ancient DNA recovered from these specimens, given Loas' hot, humid climate, but wouldn't it fascinating to find out what mtDNA group they belong to. Would it M, N or even L? What's your opinion Andrew? NeilB
@NeilB
Probably a mix of M and N.
The transition from L3 to M and N brews for a long time in SW Asia before breaking out to South Asia and beyond. Essentially no pre-Bronze Age L is found outside of Africa and the Levant.
The relict populations of Australasia are probably the hardest evidence: "mtDNA haplogroups acknowledged as uniquely Aboriginal Australian fall within macrohaplogroups M and N (including R). Haplogroups presently considered autochthonous to Australia are N13, O, M42a, M14, M15, S and numerous P subtypes (P3a, P4b, P5, P6, P7, P8). Current time to most recent common ancestor (TMRCA) estimates indicate great antiquity for most of them." https://www.nature.com/articles/jhg2016147
Australian aborigines and Papuans have a mix of M haplotypes, one N haplotype, and some P haplotypes which are a descendant of R which is a descendant of N.
Wasn't there some hints that Papuan and Australian Aborigines are themselves the product of a fusion of two preceding populations though? I believe the original Denisovan paper modelled them as originally having ~25% Denisovan ancestry, before it was watered down with later admixture. I could see it being possible that M and N represent distinct waves that later merged in South and SE Asia before spreading further.
I'd note these dates overlap with the Toba catastrophe. Maybe our modern human relatives took advantage of an ecological void left by that eruption?
"Wasn't there some hints that Papuan and Australian Aborigines are themselves the product of a fusion of two preceding populations though?"
Australian Aborigines probably have some modest admixture from the time that the Dingo was introduced, but that is possible to distinguish statistically. There could have been two waves, but the window of opportunity before rising sea levels made the passage to Australia much more challenging without advanced maritime technology is pretty narrow.
The time constraints on further admixture in Papuans are less strong.
"I believe the original Denisovan paper modelled them as originally having ~25% Denisovan ancestry, before it was watered down with later admixture."
I thought (from memory alone) it was closer to 1/8th, but you may be right and are certainly in the right ballpark. But, clearly, there is no Denisovan or Neanderthal mtDNA in any modern human DNA, ancient or modern, that has ever been genotyped.
"I could see it being possible that M and N represent distinct waves that later merged in South and SE Asia before spreading further."
This is plausible and indeed, likely.
"I'd note these dates overlap with the Toba catastrophe. Maybe our modern human relatives took advantage of an ecological void left by that eruption?"
My hypothesis is that the jungles of Southeast Asia and/or the presence of H. Erectus, created a barrier to modern human expansion out of South Asia, and that the Toba eruption temporarily minimized this/these barriers sufficiently that modern humans were granted a window of expansion that also resulted in the extinction or near extinction of H. Erectus (but not of Denisovans, who may have ultimately succumbed to competitive pressure of some kind from modern humans with whom the first wave admixed, but who were extinct, or very nearly so, outside some relict populations near Tibet, by the time that the second wave of modern humans into Asia arrived).
Second wave modern humans also almost totally replaced first wave modern humans, with only modest admixture with first wave modern humans in Asia, in mainland Asia and west of the Wallace line, midway into the Upper Paleolithic era. It isn't entirely clear what gave the second wave modern humans such a strong advantage over the first wave modern humans, although one plausible possibility is the domestication of dogs by second wave modern humans.
That question re: second wave (ie 55kya) modern humans is really the most interesting puzzle in my opinion. What made these humans so successful?
I think Oceanians have both first and second wave ancestry though - which would mean the late introduction of the dingo rules out domestic dogs as the source of this competitive advantage.
From what I read, I believe the two OoA waves followed different routes: first one North (mtDNA M), second one coastal south Asia (mtDNA N). How long ago the first wave left Africa is debatable, but certainly pre-Toba. Maybe as long ago as 120K? Neil B
The domesticated dog, the dingo, arrived in Australia about 8 kya, and this had a massive environmental impact resulting in a secondary wave of mass extinction in Australia.
The dog was domesticated, probably in SE Asia, ca. 35 kya, which is about the right timing for the Y-DNA O wave, which is quite plausibly what replaced Denisovan admixed first wave humans on the mainland.
It could be that there was a first wave ca. 75 kya to go from South Asia into Southeast Asia, and another ca. 55 kya before easy passage to Papuan and Australian territories was closed by rising sea levels, and merged without destroying each other since neither had a decisive advantage, only for the merged population to be largely replaced by a dog wielding Y-DNA O people ca. 35 kya as far as they could get (not past the Wallace line).
"From what I read, I believe the two OoA waves followed different routes: first one North (mtDNA M), second one coastal south Asia (mtDNA N)."
The usual assumption is that M was a southern coastal route and N was a northern route, although the newer data tends to favor a counterclockwise rotation for N on the coastal route as well, then up the east coast of Asia and crossing Northern Asia from east to west.
Part of the problem is that the Last Glacial Maximum exterminated almost all Northern Asian modern humans, leaving gaps in the phylogeny, rather than closely chained intermediate steps to track.
"How long ago the first wave left Africa is debatable, but certainly pre-Toba. Maybe as long ago as 120K?"
Out of Africa at 120K is plausible and has some limited human remains support in the Levant, and human tool relic support in Arabia. There are human tools relics in South Asia at least well pre-Toba.
The proto-populations of mtDNA M and N were probably isolated from Africa in the Middle East, West Asia, and South Asia without seriously expanding further on a permanent basis until much later, which is how even very early mtDNA M and mtDNA N among Papuans and Aboriginal Australians gets so distinct and diverged from mtDNA L.
This may have happened in two or three steps rather than filling out immediately.
The early side of this time frame in the Near East is the likely time frame and place of Neanderthal admixture for non-Africans.
This limited Out of African expansion may have been frozen and continued until about 75 kya in the SE Asian direction (jungles/archaic humans forming a barrier in that direction until Toba) and in the European direction until about 40-45 kya (Neanderthals kept them at bay until volcanos/climate issues led to Neanderthal collapse and opened the door for modern humans to enter Europe).
The Northern Eurasia was starting to get less habitable by ca. 30 kya, and reached last Glacial Maximum by 20 kya. The modern humans who went to the New World via Beringia had dogs before their entry into Berginia well before the LGM.
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