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Humans: Dispersing and Dispersing

7531-1477645031Eurogenes points me to this interesting conference with a book of abstracts, Human Dispersals in the Late Pleistocene – Interdisciplinary Approaches Towards Understanding the Worldwide Expansion of Homo sapiens. Below are those of interest to me….

Philipp Gunz

Max Planck Institute for Evolutionary Anthropology
Leipzig, Germany

Evolution and development of the modern human
face and brain

A number of fossils from North, South, and East Africa document the early stages of our species, and fossils from the Levant document the presumed first wave of migration out of Africa. The exact place and time of our species’ emergence remain obscure as large gaps in the fossil record and the chronological age of many key specimens make it difficult interpreting the evolutionary processes and population dynamics shaping the cranial diversity of modern humans. Here we use 3D geometric morphometrics based on landmarks and semilandmarks to compare facial and endocranial shape in a worldwide sample of recent and fossil humans from Africa, Europe, and Asia.

Our data support a complex evolutionary history of our species involving the whole African continent. Regarding facial shape, we find that even the early H. sapiens specimens fall within the shape variation of recent modern humans. Endocranial shape, however, changes considerably within the Homo sapiens lineage.

51t3ZeiK+vL._SY344_BO1,204,203,200_ I think I understand archaic introgression better now. Humans really care about faces. Brains? Not as much. If our species developed its normal range of species-typical faces rather early on than we’d recognize each other as conspecifics, despite widespread phenotypic differences (including likely cognitive and behavioral) and genetic divergence. Basically, it’s just like the Trojan War; a face can launch ships, and mediate gene flow.

John Hawks

University of Wisconsin-Madison, USA

African population diversity and its relevance for human dispersals

As modern humans dispersed throughout the world, they encountered and mixed with populations with much greater genetic distinctiveness than any living humans today. This process is now relatively well documented by ancient DNA in Eurasia and Australasia due to the ancient DNA records of Neanderthal and Denisovan samples. Within Africa this process of contact and mixture between genetically differentiated populations also took place, evidenced by the evidence of population mixture from genomes of some African populations today. The process began earlier, well before 100,000 years ago, and may have extended over a longer period of time. The evidence suggests that modern humans originated and began their dispersals within an African continental context equally or more genetically structured than Eurasia. However the fossil record of this population is very sparse, and it is not evident how archaeological distributions may relate to biological populations. Here I discuss the implications of this population structure for human dispersal and adaptability. T he modern human phenotype originated as one well adapted for dispersal within a long-existing network of successful populations of potential competitors.

Basically it strikes me that John is developing and extending the neo-multiregionalist framework that he was operating within in the early 2000s. Also, African substructure is a thing. A major thing.

Finally, but not least:

Stephan Schiffels

Max Planck Institute for the Science of

Human History, Jena, Germany

Analysing Australian genomes to learn about early modern human dispersal out of Africa

When and how modern humans left the African continent is still a debated question. Recently, three projects have analysed new genetic data from modern populations in Papua New Guinea and Australia, which has provided new insights on this topic. I will present analyses from one of these publications (Malaspinas et al. 2016), and compare results with findings from the two other projects (Mallick et al. 2016, Pagani et al. 2016). Here, we used MSMC2, a novel computational framework to analyse the distribution of times to the most recent common ancestor along multiple sequences. We find that all non-African populations that we analysed, including Australians, experienced a very similar population bottleneck in the past, consistent with only one out-of-Africa migration for all extant non-African populations. At the same time, we find evidence that some African populations are more distantly related to Australians than to Eurasian populations, and we show that this result is robust to haplotype phasing errors and archaic introgression. We interpret our result as evidence for gene flow between some Africans and Eurasians after the initial split, which is also consistent with results from other population genetic methods. Our analysis suggests that in order to understand human dispersal out of Africa, we need to better understand ancient population substructure within Africa, which is an important direction for future research.

Again, ancient African substructure. No coincidence. Talk to the cutting edge people in the field, and this is the fabric of reality that the knife’s edge is going to slice in the near future. Second, I do believe it is likely that there was non-trivial gene flow between Sub-Saharan Africa and Western Eurasia over the past 50,000 years. Some of this is masked perhaps by low levels, but, just as likely in mind, ancient African structure which has been erased due to population turnover.

 
• Category: Science • Tags: Genetics, Human Evolution 
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  1. Is it at all possible that the Denisovan admixture in Australians contributes to their greater distance from Africans (Or is that accounted for—I would guess it would be?)?

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  2. Dear Razib Khan,

    This an out of topic question but related to genetics. I notice that Southeast Asians like Burmese, Cambodians, Malays/Indonesians and Thais usually score South Asian components in ADMIXTURE calculators. Do you know if such SE Asian populations have any West Eurasian/West Eurasian-like ancestry and how much would they have? Or is their “South Asian” mostly ASI?

    I will kindly appreciate your generous replies.

    Thank you very much

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  3. [Blockquote]Razib Khan [/Blockquote]

    Apologies for asking the same question again. But at first I did not quote the question to you.

    Do you know if Southeast Asians like Burmese, Cambodians, Malays or Thais have minor West Eurasian admixture? I wonder about this because these SE Asians usually score substantial South Asian in ADMIXTURE calculators. Do their”South Asian” component have any West Eurasian/West Eurasian-like ancestry and how much would they have? Or is their “South Asian” mostly ASI?

    Thank you very much.

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