DNA Study Offers Clues to Contact Between Modern Humans and Neanderthals

PHILADELPHIA, PENNSYLVANIA—According to statement released by the University of Pennsylvania, scientists had previously surmised that the lack of Neanderthal DNA on modern human X chromosomes, which are inherited through the maternal line, was due to genetic incompatibility that may have caused health problems eliminated through the process of natural selection. Sarah Tishkoff and Alexander Platt of the University of Pennsylvania and their colleagues tested this idea by looking for modern human DNA on Neanderthal X chromosomes, and compared the results with the genomes of Africans whose populations had never mixed with Neanderthals. “What we found was a striking imbalance,” said team member Daniel Harris. “While modern humans lack Neanderthal X chromosomes, Neanderthals had a 62% excess of modern human DNA on their X chromosomes compared to their other chromosomes,” he explained. If the modern human and Neanderthal genes had been incompatible, modern human DNA would have been missing from the Neanderthal X chromosome. But the abundance of modern human DNA in the Neanderthal X chromosome suggests that the mixing occurred more often between modern human women and Neanderthal men. “Mating preferences provided the simplest explanation,” Platt said. For more, go to "Neanderthal Genome," one of ARCHAEOLOGY's Top 10 Discoveries of the Decade.