New genetic research suggests that interbreeding between Neanderthals and early modern humans occurred more often between male Neanderthals and female humans. The study, published in Science, offers a new explanation for why Neanderthal DNA is largely absent from the human X chromosome.
Researchers led by Alexander Platt and Sarah Tishkoff at the University of Pennsylvania compared DNA from Neanderthal remains (including the Altai, Chagyrskaya and Vindija individuals) with genetic data from sub-Saharan African populations that lack Neanderthal ancestry. They found that Neanderthal X chromosomes showed a 62% excess of modern human DNA, mirroring the scarcity of Neanderthal DNA on the human X chromosome.
Because females carry two X chromosomes and males only one, the direction of mating would shape how genes spread. If male Neanderthals partnered more frequently with female humans, fewer Neanderthal X chromosomes would enter the human gene pool. The findings suggest long-term mating patterns, rather than genetic incompatibility, may explain the so-called "Neanderthal deserts" in human DNA...