AsianScientist (Mar. 2, 2016) – An international research team has identified an interbreeding event between Neanderthals and modern humans that occurred about 100,000 years ago. Notably, this is tens of thousands of years earlier than previous scientific estimates. Their discovery was published in Nature.
The authors, led by Dr. Fu Qiaomei from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, have pieced together the first genetic evidence supporting the scenario that some modern humans may have left Africa in an early migration.
These modern humans then mixed with archaic hominids in Eurasia before the ancestors of present-day non-Africans migrated out of Africa less than 65,000 years ago.
The breakthrough involves an Altai Neanderthal whose remains were found in a cave in the Altai Mountains in southern Siberia. The individual shows signs of gene transfer, or gene flow, from modern humans. In comparison, two Neanderthals from European caves, who were also sequenced for this study, as well as a Denisovan, all appeared to lack specific DNA derived from modern humans.
Research also found that a demographic model that estimates gene flow from these early modern humans into the ancestors of the Altai Neanderthal to be about 1.0-7.1 percent. Although the exact source is unclear, the authors suspect that it may have come from a deep population that either split off from the ancestors of present-day Africans or from one of the early African lineages. Computer simulations also support this data.
The team was able to further calculate that early modern human introgression into the Altai Neanderthal lineage occurred 100,000-230,000 years ago. Introgression describes the incorporation of genes from one species into the gene pool of a second, divergent species.
This introgression is much earlier than previously reported gene flow from Neanderthals into modern humans outside Africa (47,000-65,000 years ago).
Possibly, there was an extended lag between when this group branched off from the modern human family tree, roughly 200,000 years ago, and when its members left their genetic mark in the Altai Neanderthal, about 100,000 years ago, before the group became extinct.
The article can be found at: Kuhlwilm et al. (2016) Ancient Gene Flow from Early Modern Humans into Eastern Neanderthals.
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Source: Chinese Academy of Sciences; Photo: Erich Ferdinand.
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