Dad's a Neanderthal, Mom's a human, I'm in therapy

Humans and our close relatives, Neanderthals, produced children together many times before the latter went extinct about 40,000 years ago. As a result, the vast majority of people living today carry a pinch of Neanderthal DNA--the enduring proof of past copulations between our species.

Now, scientists have proposed that these prehistoric partnerships overwhelmingly occurred between Neanderthal males and females of our own species, Homo sapiens, with far fewer couplings between Neanderthal females and human males. This strong sexual bias provides the most "parsimonious" explanation for the uneven distribution of Neanderthal alleles (variants of specific genes) in modern human genomes, according to a new study.

"One of the notable features evident in alignments of Neanderthal genomes to those of modern humans is the presence of 'Neanderthal deserts' within modern human genomes: genomic regions where Neanderthal alleles are conspicuously rare in the modern human (and ancient modern human) gene pool," said researchers led by Alexander Platt of the University of Pennsylvania.



In particular, the team noted that Neanderthal deserts show up on the human X chromosome, which they think hints at a strong sex bias toward breeding between Neanderthal males and human females.

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