In a genomic study encompassing more than 300 genomes, researchers determined the time period during which Neanderthals interbred with modern humans, starting about 50,500 years ago and lasting about 7,000 years — until Neanderthals began to disappear. That interbreeding left Eurasians with many genes inherited from our Neanderthal ancestors, which in total make up between 1% and 2% of our genomes today.
To date, sequencing of Neanderthal and Denisovan genomes has revealed substantial gene flow between these archaic hominins and modern human ancestors, even as scientists have also reported that Neanderthal ancestry is unevenly distributed across the genome.
Moreover, certain regions of the genome — known as archaic deserts — completely lack Neanderthal ancestry, while others exhibit high frequencies of Neanderthal variants, potentially due to beneficial adaptive mutations.
However, much about the nature of this ancient admixture, including the role evolutionary forces like genetic drift or natural selection played in shaping these patterns, remains unclear.
“”The timing is really important because it has direct implications on our understanding of the timing of the out-of-Africa migration as most non-Africans today inherit 1-2% ancestry from Neanderthals,” said University of California, Berkeley’s Dr. Priya Moorjani.
“It also has implications for understanding the settlement of the regions outside Africa, which is typically done by looking at archeological materials or fossils in different regions of the world.”
“The longer duration of gene flow may help explain, for example, why East Asians have about 20% more Neanderthal genes than Europeans and West Asians.”
“If modern humans moved eastward about 47,000 years ago, as archeological sites suggest, they would already have had intermixed Neanderthal genes.”
In the study, Dr. Moorjani and colleagues analyzed genomic data from 59 ancient individuals sampled between 45,000 and 2,200…
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