• Study determines timing of neanderthal/non-African humans commingling

    From Primum Sapienti@21:1/5 to All on Wed May 22 23:32:10 2024
    https://www.iflscience.com/we-now-know-exactly-when-humans-and-neanderthals-hooked-up-74337

    ...
    It’s estimated that between 1 and 4 percent
    of the genomes of all non-African humans
    alive today come from Neanderthals. These
    genes have helped to shape our appearance
    and behavior, although until now researchers
    had struggled to recreate the encounters that
    resulted in this exchange of genetic material.

    To piece the story together, the authors of
    an as-yet un-peer-reviewed study analyzed the
    genomes of 59 ancient Homo sapiens individuals,
    all aged between 45,000 and 2,200 years old.
    Of these, 33 lived more than 10,000 years ago,
    with Siberia’s famous Ust’-Ishim man being
    among the oldest of the lot.

    These prehistoric genomes were then compared to
    those of 275 present-day humans from across the
    world. Using computer software, the researchers
    were able to trace the evolution of Neanderthal
    genes across the millennia and work out exactly
    how many generations it would have taken for
    them to diverge in the way they did.

    “By measuring the ancestry covariance for each
    of the 16 ancient individuals that lived between
    40,000 and 20,000 [years ago], we infer that the
    Neandertal gene flow occurred between 321 and
    950 generations before these individuals lived,”
    write the study authors. More specifically, they
    found that the flow of Neanderthal DNA into the
    modern human genome occurred over a period of
    6,832 years, with the average time of
    introgression being 47,124 years ago.
    ...


    https://www.biorxiv.org/content/10.1101/2024.05.13.593955v1
    Posted May 13, 2024.
    Neandertal ancestry through time: Insights from
    genomes of ancient and present-day humans


    Abstract
    Gene flow from Neandertals has shaped the
    landscape of genetic and phenotypic variation
    in modern humans. We identify the location and
    size of introgressed Neandertal ancestry
    segments in more than 300 genomes spanning the
    last 50,000 years. We study how Neandertal
    ancestry is shared among individuals to infer
    the time and duration of the Neandertal gene
    flow. We find the correlation of Neandertal
    segment locations across individuals and their
    divergence to sequenced Neandertals, both
    support a model of single major Neandertal gene
    flow. Our catalog of introgressed segments
    through time confirms that most natural
    selection–positive and negative–on Neandertal
    ancestry variants occurred immediately after
    the gene flow, and provides new insights into
    how the contact with Neandertals shaped human
    origins and adaptation.

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