Our Inner Neanderthal

Some human X chromosomal DNA originates from Neanderthals and is found exclusively in people outside Africa

The interaction between modern humans and our Neanderthal cousins has been a source of much debate, scientific or otherwise. Till recently, the consensus was that they might have lived side by side at some point in the last 50,000 years, but their interaction may not have extended to interbreeding. With the mapping of the Neanderthal genome, it was expected that we would have a more precise answer—and that, indeed, is the case.

According to a recent paper in  Molecular Biology and Evolution: ‘Recent work on the Neandertal genome has raised the possibility of admixture between Neandertals and the expanding population of H. sapiens who left Africa between 80 Kya and 50 Kya to colonize the rest of the world. Here we provide evidence of a notable presence (9% overall) of a Neandertal-derived X chromosome segment among all contemporary human populations outside Africa… It indicates a very early admixture between expanding African migrants and Neandertals prior to or very early on the route of the out-of-Africa expansion that led to the successful colonization of the planet.’

 “This confirms recent findings suggesting that the two populations interbred,” says lead researcher Damian Labuda of the University of Montreal. “In addition, because our methods were totally independent of Neanderthal material, we can also conclude that previous results were not influenced by contaminating artifacts,” he adds.

According to a university release: ‘Labuda and his team almost a decade ago had identified a piece of DNA (called a haplotype) in the human X chromosome that seemed different and whose origins they questioned. When the Neanderthal genome was sequenced in 2010, they quickly compared 6,000 chromosomes from all parts of the world to the Neanderthal haplotype. The Neanderthal sequence was present in peoples across all continents, except for sub-Saharan Africa, and including Australia.’

As for the impact of these genome exchanges, Labuda says, “Variability is very important for the long-term survival of a species. Every addition to the genome can be enriching.”

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Hartosh Singh Bal