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That Neanderthal question.

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Comments

  • Registered Users Posts: 3,284 ✭✭✭dubhthach


    Tibetans carry a specific gene variant which is advantageous for living at attitude (Tibetan plateau and all that). It would seem that basically they have undergone selection for this variant due to the advantage it gives them. Anyways it originates in Denisovan's. In other populations with partial Denisovan ancestry (such as Melanesians) this specific variant wasn't perserved as it didn't offer any evolutionary advantage in context of Pacific islands.


  • Registered Users Posts: 5,504 ✭✭✭tac foley


    So, too, do Peruvians. Genetically optimised to live at great altitudes, their blood has more oxygen-carrying capacity, their lungs have great volume and many other 'modifications', to enable them to 'linve long and prosper' above 10,000 feet.


  • Moderators, Science, Health & Environment Moderators, Society & Culture Moderators Posts: 60,027 Mod ✭✭✭✭Wibbs


    Yep as you say Tac Peruvians have a similar suite of genes from the Denisovans as the Tibetan and Nepalese. Funny enough, of the populations so far sampled Peruvians show the most Denisovan and Neandertal genes and with longer sequences to boot of all. They're the most genetically distinct from African populations. They also show much less admixture with colonising peoples from Europe compared to other Native South American populations. They look like the "purest" population most related to the first settlers in the Americas. Which might explain the archaic levels going on. Their ancestors would have been close to, or even had the oul dance with no pants with archaics in their original homeland. But because their ancestors made it to Peru and were then much more isolated from other Native Americans, held onto more of their archaic genes.

    Rejoice in the awareness of feeling stupid, for that’s how you end up learning new things. If you’re not aware you’re stupid, you probably are.



  • Registered Users Posts: 3,284 ✭✭✭dubhthach


    Relevant video. It's just over an hour long:
    Ancient DNA and the New Science of the Human Past -- November 2018 at Havard



    he covers European population dynamics from 32m in, he gets to population turnover in Britain and Iberia around 48m+ (references various papers)


  • Registered Users Posts: 14,538 ✭✭✭✭Poor Uncle Tom


    Brilliant, I'd love to see an overlay of archaeological events and would like to see if there are any other large migratory events.


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  • Registered Users Posts: 3,284 ✭✭✭dubhthach


    Brilliant, I'd love to see an overlay of archaeological events and would like to see if there are any other large migratory events.

    Well it would seem the transition to Bronze age was the last time there was major population turnover in Europe. After that it's probably a case that various peoples moving around are actually very alike. After all there isn't a huge amount of difference between various Europeans.

    There was a recent paper about Germanic migration in post-Roman period, what will be interesting is when we start seeing samples from say the Balkans covering the post-Roman period given the large scale Slavic migrations that are known both from history and linguistically (some would argue that mainland Greeks are shifted towards Poles for example due to this)

    From an Irish point of view we are still waiting on paper with regards to 50+ genomes covering Mesolithic, Neolithic, Bronze and Iron ages. It would seem the PhD attached to it was awarded, but thesis is embargoed until 2020 probably until scientific papers are published

    http://www.tara.tcd.ie/handle/2262/82960
    A Genomic Compendium of an Island: Documenting Continuity and Change across Irish Human Prehistory
    Abstract:
    This thesis provides an initial demographic scaffold for Irish prehistory based on the palaeogenomic analysis of 93 ancient individuals from all major periods of the island's human occupation, sequenced to a median of 1X coverage. ADMIXTURE and principal component analysis identify three ancestrally distinct Irish populations, whose inhabitation of the island corresponds closely to the Mesolithic, Neolithic and Chalcolithic/Early Bronze Age eras, with large scale migration to the island implied during the transitionary periods. Haplotypic-based sharing methods and Y chromosome analysis demonstrate strong continuity between the Early Bronze Age and modern Irish populations, suggesting no substantial population replacement has occurred on the island since this point in time. The Mesolithic population shares high genetic drift with contemporaries from France and Luxembourg and shows evidence of a severe inbreeding bottleneck, apparent through runs of homozygosity (ROH). Substantial contributions from both Mediterranean farming groups and northwestern hunter-gatherers are evident in the Neolithic Irish population. Moreover, evidence for local Mesolithic survival and introgression in southwestern Ireland, long after the commencement of the Neolithic, is also implied in haplotypic-analysis. Societal complexity during the Neolithic is suggested in patterns of Y chromosome and autosomal structure, while the identification of a highly inbred individual through ROH analysis, retrieved from an elite burial context, strongly suggests the elaboration and expansion of megalithic monuments over the course of the Neolithic was accompanied in some regions by dynastic hierarchies. Haplotypic affinities and distributions of steppe-related introgression among samples suggest a potentially bimodal introduction of Beaker culture to the island from both Atlantic and Northern European sources, with southwestern individuals showing inflated levels of Neolithic ancestry relative to individualised burials from the north and east. Signals of genetic continuity and change after this initial establishment of the Irish population are also explored, with haplotypic diversification evident between both the Bronze Age and Iron Age, and the Iron Age and present day. Across these intervals selection pressures related to nutrition appear to have acted, with variants involved in lactase persistence and skin depigmentation showing steady increases in frequency through time.


  • Registered Users Posts: 14,538 ✭✭✭✭Poor Uncle Tom


    No longer the case of looking for the 'missing link' it's now a case of uncovering the hidden chain.

    The fantastic irony, that it's taken until very recently (10 - 12 years ago) to prove interbreeding between modern humans and Neanderthals actually happened and to see the evolving theories being proven / disproven so quickly since.


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