Ever since the discovery in 2010 that Neanderthals interbred with the ancestors of living humans, scientists have been trying to determine how their DNA affects people today. Now two new studies have traced the history of Neanderthal DNA, and have pinpointed a number of genes that may have medical importance today.

Among the findings, the studies have found clues to the evolution of skin and fertility, as well as susceptibility to diseases like diabetes. More broadly, they show how the legacy of Neanderthals has endured 30,000 years after their extinction.

“It’s something that everyone wanted to know,” said Laurent Excoffier, a geneticist at the University of Bern in Switzerland who was not involved in the research.

Neanderthals, who became extinct about 30,000 years ago, were among the closest relatives of modern humans. They shared a common ancestor with us that lived about 600,000 years ago....