July 17, 2013

Homo sapiens from Central China dated to 81-101 Ka BP

I just received notice (h/t David) of this most important finding and dating:

Guanjun Shen et al., Mass spectrometric U-series dating of Huanglong Cave in Hubei Province, central China: Evidence for early presence of modern humans in eastern Asia. Journal of Human Evolution 2013. Pay per viewLINK [doi:10.1016/j.jhevol.2013.05.002]

Abstract

Most researchers believe that anatomically modern humans (AMH) first appeared in Africa 160-190 ka ago, and would not have reached eastern Asia until ∼50 ka ago. However, the credibility of these scenarios might have been compromised by a largely inaccurate and compressed chronological framework previously established for hominin fossils found in China. Recently there has been a growing body of evidence indicating the possible presence of AMH in eastern Asia ca. 100 ka ago or even earlier. Here we report high-precision mass spectrometric U-series dating of intercalated flowstone samples from Huanglong Cave, a recently discovered Late Pleistocene hominin site in northern Hubei Province, central China. Systematic excavations there have led to the in situ discovery of seven hominin teeth and dozens of stone and bone artifacts. The U-series dates on localized thin flowstone formations bracket the hominin specimens between 81 and 101 ka, currently the most narrow time span for all AMH beyond 45 ka in China, if the assignment of the hominin teeth to modern Homo sapiens holds. Alternatively this study provides further evidence for the early presence of an AMH morphology in China, through either independent evolution of local archaic populations or their assimilation with incoming AMH. Along with recent dating results for hominin samples from Homo erectus to AMH, a new extended and continuous timeline for Chinese hominin fossils is taking shape, which warrants a reconstruction of human evolution, especially the origins of modern humans in eastern Asia.

In other words: strong material evidence is quickly piling up in favor of a Homo sapiens "fast" colonization of Southern Asia (and as far NE as Hubei!) around 100 or at least 90 Ka BP. 


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11 comments:

  1. I would really love to see some critical analysis of how solid the ID of the teeth as AMH rather than archaic is from someone who is personally an independent expert in physical anthropology like John Hawks or Julien Riel-Salvatore. This is the kind of thing where hominin teeth all look alike to non-experts or look different only in ways that are within natural variation for a single species, while ambiguity even to an expert is telling. There is really no substitute in matters like this for raw cumulative experience of having seen lots and lots and lots of AMH and archaic and primate teeth.

    I am not yet convinced that the Chinese scholarship can be taken at face value, but if some independent experts are really convinced that these are AMH teeth and don't see obvious flaws in the U-dating methodology then the next step is to see if this can be corroborated with any archaeological data such as lithic tools or ecological impacts in regional flora and fauna consistent with the arrival of AMHs at that time.

    It is a very hard sell to argue, even with a few old AMH-like teeth that there were modern humans on a path all of the way from Bangladesh to Vietnam to multiple locations in China for 50,000 years +/- before indisputable artifact traces of AMHs become common over the entire range around the time of the UP, without leaving any artifacts that are clearly not in continuity with the archaelogical record of the previous 800,000+ years or so. And, as far as I have learned so far, this just isn't there and as I understand it, the lithic technology of SE Asia and E Asia is remarkably static during that period with only minor developments that appear over very long (hundreds of thousands of years apart) subdivisions in style.

    In the absence of something to corroborate the physical anthropology of the teeth at those ages, I'm strongly predisposed to favor a convergent evolution hypothesis.

    Yes, the absence of evidence isn't necessarily evidence of absence. But, if you look at the unmistakable archaeological signatures of AMH arrivals in Australia and Melanesia, in Europe, in Siberia, and in the Americas at various points during the UP, and the steady persistent of AMH artifacts in South Asia in continuity with each other from pre-Toba to ca. 45kya, there is good cause to expect more than has been found to date in association with the very thin skeletal remains found. Even if the old Chinese remains are AMH, the absence of associated distinctively AMH artifacts until the UP makes a pretty good cause for there being a behavioral modernity revolution at the UP that isn't as stark anywhere else.

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    1. I would agree that teeth alone are often debatable about which species they belong, although in East Asia, being the only known other species H. erectus (more distant from us than Neanderthals), this issue should be less problematic.

      "I am not yet convinced that the Chinese scholarship can be taken at face value"...

      I'm not convinced that any scholarship can be taken at face value but this does not normally depend on nationality. In the West there are also individuals pushing their own agendas instead of doing objective science. I see no particular reason to doubt the Chinese in particular.

      "... before indisputable artifact traces of AMHs become common over the entire range around the time of the UP"...

      The true problem is that there are no AMH typical artifacts (and certainly not UP or mode 4, which is a technology type shared with Neanderthals long before most H. sapiens began using it). There is no "modern human behavior", there is nothing that H. sapiens does necessarily that is different to other Homo species; if anything our potential may be greater (very debatable) but the manifestations of such potential even today vary a lot.

      "In the absence of something to corroborate the physical anthropology of the teeth at those ages"...

      Zhirendong: whole jaw with chin, reasonably well dated around 100,000 BP.

      "... the absence of associated distinctively AMH artifacts until the UP makes a pretty good cause for there being a behavioral modernity revolution at the UP that isn't as stark anywhere else".

      That's a myth: a modern Eurocentric construct! Mode 4 (UP, LSA) is just another technological variant, not necessarily much better than mode 3 (MP, MSA). There's nothing anyhow in mode 4 that lets us assume a mental revolution, in fact the whole idea of a biological/neurological revolution associated to mode 4 is as idiotic as presuming that people would be intrinsically different before and after the industrial revolution or the agricultural revolution, which are much more striking conceptual and cultural milestones than the MP-UP transition. Before and after that transitions the lifestyle was essentially the same, in fact there are more differences, for example, between Magdalenian and Aurignacian or Gravettian Europe than between these and the Mousterian period (excepting the species in charge, of course).

      "Modern human behavior" is nothing but a self-satisfying fallacy. Rantings of old academics raised too religiously to accept that humans are just big headed animals.

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    2. Dienekes has a nice quote from the body of the paper today that addresses some of my concerns about the need to corroborate the results in light of the gap of other evidence, although not completely.

      The concern about Chinese scholarship is that there is pretty good circumstantial evidence from other Chinese papers I've read over the years of tailoring analysis and conclusions to political ideology in a country where there is a still quite powerful one party state and rather weak academic freedom, and there have also been papers now and then that suggest that the typical standard of competency in published archaeology/anthropology in China is not always state of the art. Obviously, none of that means that one can't do very good work in China (as long as it doesn't take on any sacred cows in the Chinese political climate by using bland or obscure descriptive language rather than more clear but more sensitive language). Also, it isn't unreasonable to be more skeptical about a paper from a Chinese dig than one from Africa, Europe or North America on the grounds that the proportion of meaningfully less competent published academic work in the field is smaller. Bad papers get published everywhere, but a higher proportion are published in China than in many places.

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    3. I seems to me slashing out 1/5 of humankind on a very speculative reasoning "circumstantial evidence", "one party system" (why not the twin party system? I see no difference)... I know that in China (but not only there) there's some pressure to publish and that sometimes number matters more than quality. But that seems about it and it's obviously not the case here at all (this had to be published, there's no doubt about it).

      Dienekes seems to have got full access to the paper and one of his excerpts is very appropriate: why do authors like Mellars (sacred cow, twin party system, winner-takes-all districts, extreme concentration of media ownership, sensationalist "science", totalitarian control of communications, blah-blah) decides to blatantly ignore all the evidence about very old human presence in East Asia? It's this tooth, it's Zhirendong, it's Liujiang, and is also other evidence.

      We are not talking anymore of a single doubtful case (Liujiang) but of the piling up of more and more evidence of greater and greater quality.

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  2. Andrew,

    Significant parallel evolution is something that typically happens on the time scale of many tens of millions of years, whereas parallel cultural evolution happens all the time (agriculture, stone houses, cities, metal working, etc.). It has been shown over and over again that there is no unique association between AMHs and UP stone technologies (although there is, the other way around).

    I don't find it hard to believe at all that AMHs initially had a hard time coming to domination - it's the rule, not the exception, wherever we look, including Africa, Europe, and N and S and E Asia.

    Conversely, I do believe that by around 50,000 ya we had assembled a sufficient cultural package to expand into more challenging (often colder) regions and to take on other, ancient human groups. There may have been a small evolutionary portion associated with that (not only cognitive, but also, e.g., disease resistance via admixture), the best evidence for which so far is the agreeing calculated time of divergence between Asians and Europeans (which, however, is of course not very accurate). Even that could just be a coincidence: when the package got established, people went all over the place, mixing, and erasing much of the differences accumulated in the previous 40,000 years. We pretty much know this happened with Europeans, who appear to have proto-Mongoloid admixture (which is also supported by a trail of archaeological evidence across Siberia, the Altai, and towards Europe).

    BTW, the paper has US and Australia - resident collaborators, in case that helps re credibility.

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    1. It's not that I disagree with the bulk of what you say but there is something I really don't like: the opposition you make between "Asians" and "Europeans".

      For anthropological purposes such categories are simply invalid. It'd be West Eurasians, East Asians, South Asians, etc. There's nothing substantial differentiating, say, Germans (Europeans) from Iranians (Asians), not at global or Eurasian continental level certainly. And this identity, even if surely reinforced by more recent flows in both senses, originated with the founder effects associated with the colonization of the Neanderlands some 50,000 years ago.

      You mention Altai for example but for all the Upper Paleolithic and later until the Bronze Age, Altai was quite strictly part of West Eurasia. Only (West) Siberia senso stricto may be more ambiguous but we don't have really any Paleolithic evidence for that area AFAIK.

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    2. Genetic evolution on the scale of hundreds of thousands years is well documented in primates including hominins. Moreover, changes in evolutionary pressures are probably more important in the rate of evolutionary change than random average evolutionary drift range. Punctuated evolution is a common pattern.

      If changes in evolutionary pressures explain the rise of modern humans as a species, then one would expect contemporaneous archaic hominin populations to be changing via evolution in the same direction. In the case of East Asian hominins, there is a roughly 1 million year span over which mutation driven diversity and variation within the species that can lead to rapid evolution change by favoring some of the variants that become fitness enhancing when pressures favoring some variant emerge, to develop within that population, which is quite consistent with precedents in other species.

      No one disputes that cultural evolution has been key for humans in the last 10,000 years and really 50,000+ years. But, that doesn't mean that all existing hominin species aren't constantly evolving genetically as well and if the pressures are in the same direction we would expect convergence rather than divergence over time.

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    3. "If changes in evolutionary pressures explain the rise of modern humans as a species, then one would expect contemporaneous archaic hominin populations to be changing via evolution in the same direction".

      And in fact there is something of that: http://forwhattheywereweare.blogspot.com/2012/09/evolving-bigger-brains-everywhere.html

      But so far not a single H. erectus nor Neanderthal has a chin, for example.

      Also the ancestral genetic diversity of the genus Homo in Africa was necessarily much greater than outside that continent (it is even today), favoring a more efficient evolution (more to choose from). Even the greatest artist or engineer is also to some extent dependent on the materials and pieces he/she has at hand, more so nature, which works in a largely stochastic way (trial and error).

      The chin is an extra refinement which is not really strictly necessary: it gives us a better bite but we don't really need it anyhow. Similarly other traits were probably not subject to co-evolutionary pressures, unlike bigger and more efficient brains, which are an all-purpose, always positive development, the "swiss knife" of human "biotechnology".

      Whatever the case: the Chinese evidence fits well with the Indian evidence, the Arabian evidence, the genetic evidence (not "molecular clock" but that was to be expected), the Australian evidence and even the European evidence. All fits excellently well with an initial Eurasian expansion of around 100 Ka.

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    4. I suspect that the fitness selection impact of tooth morphology is greater than the selective pressure on chins. The chin bone evidence is therefore should be more valuable in distinguishing migration from convergent evolution than teeth or brain size.

      Honestly, I'm at a point now where four to six decent gap filling finds, including at least at least one with remains and one with tools during the "gap period" in the middle of SE Asia somewhere (e.g. Thailand or Cambodia) would have me pretty much convinced that modern humans made it very rapidly from Out of Africa to East Asia ca. 100 kya. The absence of H. Erectus after 100 kya is also somewhat persuasive.

      I wouldn't trust modern population genetics to clarify the issue much because it looks like some population had a quite possibly disruptive expansion of some population with demic impact probably took place around the UP, and the UP disruption, on top of the known Neolithic and historic era migration waves in the region could have diluted the first contact population to negligible levels in modern populations - something that the lack of mainland Denisovan admixture tends to corroborate unless mainland SE Asia and East Asia was populated by non-Denisovan archaic hominins who were reproductively incompatible with modern humans for reasons either biological or cultural.

      Even assuming that the UP was purely cultural/technology driven, the possibility that First contact AMHs had less than 12.5% archaic hominin admixture, that UP wave migrants replaced 80%+ of the AMH gene pool ca. 45,000-55,000 years ago in Asia, and that Neolithic waves replaced 80%+ of the late UP gene pool again, leaving less than 0.5% archaic Asian hominin admixture in the modern mainland gene pool, could account for what we see now, and even if Denisovans were as much as 20% H. Erectus, the H. Erectus share of the mainland Asian gene pool would be 0.1% or less. Moreover, Neanderthal and Denisovan admixture might obscure any trace H. Erectus admixture that was there.

      Another factor weighing on how to interpret these finds is that the autosomal Denisovan genome sequence does seem to make a case for the possibility that the Denisovan species is a separate species from H. Erectus (perhaps a core of H. Heidelbergis with Neanderthal and H. Erectus and even a splash of AMH admixture). It could be that Denisovan arrived first via a Northern route from Europe ca. 100kya-200kya after displacement by newly evolved Neanderthals there, created competition that lead to population collapse of H. Erectus in China and Indonesia, left the remains and artifacts that are being classified as possible AMH in China, and then were themselves displaced by AMHs sometime post-Toba with later waves of AMH migrations and expansions diluting Denisovan admixture in mainland Asia to nearly zero today. Thus, H. Erectus wouldn't have been still around in any meaningful numbers to admix with the first contact AMHs who would have encountered the newly arrived Denisovans instead. We can't currently associate Denisovans with any particular species - so even morphology like a chin wouldn't necessarily rule them out (particularly if they had minor AMH admixture).

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    5. IF the UP migrants originating in Altai would have replaced the East Asian aboriginal gene pool as you imagine, then East Asians would look (genetically and phenotypically) more West Eurasian than South Asians. It's not the case AT ALL. In fact the genetic diversity of East Asia (at least haploid) is so large compared with West Eurasian one that what you say is simply unthinkable. Additionally none of their lineages appear to have left any legacy in the West (excepted proto-Amerindian Y-DNA Q and almost nothing else). The only consistent conclusion is that there was no replacement whatsoever but just a slow cultural flow by contact.

      "We can't currently associate Denisovans with any particular species - so even morphology like a chin wouldn't necessarily rule them out (particularly if they had minor AMH admixture)".

      We do associate them with H. neanderthalensis (no chin) and H. erectus (no chin). The chin is exclusive of H. sapiens (with very rare exceptions which are all H. sapiens without chin, not the other way around).

      All I see in your comment is grabbing burning nails one after the other, sincerely.

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  3. Just insert "extreme," or "far" before that in that one sentence you criticize, and it should be clear what I meant.

    Of course, the genesis of Europeans from largely S / SE Asia and continued gene flow over time just works to reduce any differences, yet further.

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