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Thread: "Craniometrics Reveal “Two Layers” of Prehistoric Human Dispersal in Eastern Eurasia"

  1. #21
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    sorry.....
    Last edited by johen; 03-06-2019 at 06:22 PM.

  2. #22
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    According to neolithic and broze achaeology of east asia, another type of people appeared: strange big ears, slanting big almond eyes, prominent nose and large mouth.

    Hongshan neolithic:
    https://1.bp.blogspot.com/-A4Cv06rDb...HINA%2B013.jpg

    Sichuan bronze: Yellow Di? Or not.


    We can also meet this kind of large mouth and slanting big almond eyes in okunevo culture. Of course we can meet the eyes in maya and seima turbino culture. Actually seima trubino culture penetrated main land china and far reached to southeast asia 2,000bc. (maybe india also: https://anthrogenica.com/showthread....417#post550417 (#3589)

    These new observations suggest that the distribution of metal spearheads from the Seima-Turbino Culture to northern China represents the diffusion and spread of the metallurgical technique. From the metallurgical perspective in particular, the bronze casting of spearheads indicates the origin of piece-mould casting and core-casting technology, which influenced the bronze vessel casting method in China. We therefore suggest that the early Chinese metallurgy of the Lower Xiajiadian Culture in the western Liao River area can be linked to the Seima-Turbino Culture; this technique had spread from the Altai Mountain area to northern China via the Taosi Culture. After spreading to the Lower Xiajiadian Culture, it finally arrived at the Qijia Culture of Qinghai and Gansu provinces in the west

    https://www.cambridge.org/core/journ...64/core-reader

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  4. #23
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    Mt M seems gave birth to their most sublineage offspring in India.

    And there is a OoA Out of Asia theory, which means a large number of people colonize the eurasian continent when the Sahara desert become too arid in Ice age.

    There are papers about the appearance of Y haplogroup K2 and mt R in SouthEast Asia and Mt M in south Asia

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    @tuaman, I'm not sure what I'm thinking about totally adds up, but I'll try and explain.

    I guess what I'm thinking is:

    Say you have population A, and two descendents B, C. A has 3 mtdna dna types, B and C go through a bottleneck and retain 2.

    C has gone through a harsher autosomal bottleneck initially but maintains both types, possibly through chance sampling, quickly goes to a higher population size, which allows it to maintain both types in the population and downstream mtdna to increase at a high rate.

    B has gone through a weaker bottleneck, but maintains a low post bottleneck population size, meaning one mtdna type survives and few downstream clades, despite the population retaining more ancestral autosomal diversity from the weaker bottleneck.

    This just kind of requires that mtdna and autosomal don't respond the same way to long term restricted population size and population increases vs bottlenecks and a different role for chance in fairly low size populations (autosome effected more by bottlenecks, less by drift in case of long term low pop size, reverse for mtdna). I'm not totally sure that this actually works, it would be good if somehow there was some modelling for this.

    Alternatively, you could have some structured gene flow process like you describe, where the mtdna is actually coming from a restricted set of populations compared to paternal flow, enriching autosome relative to mtdna.

    Or finally, there could just be an energetic or co-evolutionary consequence of M vs N - mtdna variation is much more likely to have selective signatures than y. See a papers on mito-nuclear co-evolution: https://www.biorxiv.org/content/10.1101/349126v1

    tuaman, don't quite totally understand how your model works, probably my fault. could you do something visual to illustrate maybe? In terms of what we know from adna it doesn't seem like it's easy for the West Eurasian genepool to be substantially older than East Eurasian though - Tianyuan and Upper Paleolithic Europeans pretty much attested at the same time?

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    If that migration in the research is correct, I think Sergei opinion would be persuasive. He thought that neolithic Yangshao people in the first culture of the yellow river were speaking altaic. Hg N was also found in the yangshao. Of course, there are counter arguments that the altai does not exist or Hg is not related to language. But his opinion is considerable under the migration, I think.

    Moreover, modern Chinese is a tonal language, southern language, which appeared 4 century in China as I know (another migration from south?):

    Tonal languages require humidity:

    https://www.eurekalert.org/pub_relea...-tlr012315.php
    Last edited by johen; 03-07-2019 at 05:32 PM.

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    Circling back to this, but regarding mtDNA M in particular with its 50+ primary branches, am I missing something but how exactly can a single uniparental have that many separate lineal descendants? Each primary branch derived from the tMRCA of M is supposed to represent one actual daughter of the founding mother of all M branches, so that would mean that tMRCA M woman had over 50 daughters?

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    Quote Originally Posted by TuaMan View Post
    Circling back to this, but regarding mtDNA M in particular with its 50+ primary branches, am I missing something but how exactly can a single uniparental have that many separate lineal descendants? Each primary branch derived from the tMRCA of M is supposed to represent one actual daughter of the founding mother of all M branches, so that would mean that tMRCA M woman had over 50 daughters?
    An mtDNA mutation only comes along on average about once in 2500 years. So you expect most of the maternal descendants of the M Matriarch will be carrying the same root haplotype for a long time afterward. Hence the M Matriarch only had to have 2 daughters, those branches can (and certainly do) represent many generations of branching, but they can't be distinguished because you don't have new mutations every generation.

    In fact it is entirely possible that many primary M branches come from an expansion (or more than one) that occurred thousands of years after the initial M expansion, but with their ancestress being a woman who still carried the root haplotype of M, and hence is indistinguishable from the true root of M itself. Take haplogroup R, the main branch of N: it has 2 mutations under N - that lineage could by chance have had no mutations in that time, and all the branches of R would now be primary branches of N, even though the actual genealogy involved would be the same. IIRC this has actually been suggested as an explanation for why the TMRCA of M seems to be lower in India than elsewhere.

    The same could have happened for N or L3 or anything else. E.g. there are 7 primary branches of L3, but they could be related in any way, e.g. M and N could really be one branch, or all the African branches could be one clade which is a sister to N, etc.

    This is true of Y haplogroups as well, but mutations accumulate much faster, so it can only be a few generations blurred together.

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    These findings from cranial measurements find extra support from non-metric dental morphology42, generally believed under strong genetic control and free of environmental influence, pointing to the same two layers of populations. One grouping is apparent in Australo-Papuan and early SEA teeth, consistent with the “first layer”. Another grouping is apparent in NEA and American natives, consistent with the “second layer.” Future research may consider the deeper relation between NEA and American populations, likely involving a shared ancestry through Siberia during the Pleistocene.
    Matsumura et al. (2019) referenced recent papers in human genetics such as McColl et al. (2018) published in Science, which looked into the Two Layer model for the early peopling of Southeast Asia that is remarkably similar to the conclusion of this Craniometrics study. It would be impossible to come up with the Two Layer model by cranial measurements alone without relying on genetic studies. McColl et al. (2018) found that early genomes from Hoabinhian hunter-gatherers in Laos and Malaysia have genetic affinities with the Onge hunter-gatherers from the Andaman Islands, while Southeast Asian Neolithic farmers have a distinct East Asian genomic ancestry related to Austroasiatic populations. There were two further migratory events: 1) the expansion of speakers of Austronesian languages into Island Southeast Asia ca. 4 kya; 2) the expansion by East Asians into northern Vietnam ca. 2 kya.



    Ancient migrations in Southeast Asia
    The past movements and peopling of Southeast Asia have been poorly represented in ancient DNA studies (see the Perspective by Bellwood). Lipson et al. generated sequences from people inhabiting Southeast Asia from about 1700 to 4100 years ago. Screening of more than a hundred individuals from five sites yielded ancient DNA from 18 individuals. Comparisons with present-day populations suggest two waves of mixing between resident populations. The first mix was between local hunter-gatherers and incoming farmers associated with the Neolithic spreading from South China. A second event resulted in an additional pulse of genetic material from China to Southeast Asia associated with a Bronze Age migration. McColl et al. sequenced 26 ancient genomes from Southeast Asia and Japan spanning from the late Neolithic to the Iron Age. They found that present-day populations are the result of mixing among four ancient populations, including multiple waves of genetic material from more northern East Asian populations.

    Abstract
    The human occupation history of Southeast Asia (SEA) remains heavily debated. Current evidence suggests that SEA was occupied by Hòabìnhian hunter-gatherers until ~4000 years ago, when farming economies developed and expanded, restricting foraging groups to remote habitats. Some argue that agricultural development was indigenous; others favor the “two-layer” hypothesis that posits a southward expansion of farmers giving rise to present-day Southeast Asian genetic diversity. By sequencing 26 ancient human genomes (25 from SEA, 1 Japanese Jōmon), we show that neither interpretation fits the complexity of Southeast Asian history: Both Hòabìnhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting island SEA and Vietnam. Our results help resolve one of the long-standing controversies in Southeast Asian prehistory.

    http://science.sciencemag.org/content/361/6397/88
    Last edited by ThirdTerm; 03-30-2019 at 05:03 AM.
    Давайте вместе снова сделаем мир великий!

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    Quote Originally Posted by Megalophias View Post
    An mtDNA mutation only comes along on average about once in 2500 years. So you expect most of the maternal descendants of the M Matriarch will be carrying the same root haplotype for a long time afterward. Hence the M Matriarch only had to have 2 daughters, those branches can (and certainly do) represent many generations of branching, but they can't be distinguished because you don't have new mutations every generation.

    In fact it is entirely possible that many primary M branches come from an expansion (or more than one) that occurred thousands of years after the initial M expansion, but with their ancestress being a woman who still carried the root haplotype of M, and hence is indistinguishable from the true root of M itself. Take haplogroup R, the main branch of N: it has 2 mutations under N - that lineage could by chance have had no mutations in that time, and all the branches of R would now be primary branches of N, even though the actual genealogy involved would be the same. IIRC this has actually been suggested as an explanation for why the TMRCA of M seems to be lower in India than elsewhere.
    OK, the much slower mtDNA mutation rate makes sense of how there can be so many independent primary branches. I guess I'm still a bit confused on why one would think that it has an impact on the calculation of the tMRCA of M in India relative to other M clades in Asia. Why not just go with the more straighforward assumption that M is simply younger in India than East Asia? I mean there are multiple branches of M in India, what are the odds that all of them just had no mutations at all for several thousand years while the East Asian branches mutated along at the normal pace?

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    Quote Originally Posted by TuaMan View Post
    I mean there are multiple branches of M in India, what are the odds that all of them just had no mutations at all for several thousand years while the East Asian branches mutated along at the normal pace?
    The idea isn't that a whole bunch of branches had no mutations, it's that one branch which happened to not have any mutations expanded into many daughter branches. If that's what happened, it's only a possibility.

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