Rich sexual past between modern humans and Neandertals revealed

"Only a bit of the DNA coiled inside the cells of Europeans and Asians comes from Neandertals, but those snippets have sparked a flurry of research. In the past few years, researchers have traced them to one or two ancient encounters with our extinct cousins. Now, a report published online in Science this week details a far richer sexual past for modern humans and their archaic cousins, one that played out at multiple times and places over the past 60,000 years."