Makin’ babies with Neanderthals *changed* us.

As a species. In some pretty profound ways, Nature says. They highlight a few of the “outsize effects” our Neanderthal genes have on our lives:

Now researchers are using large genomics studies to unravel the decidedly mixed contributions that these ancient romps made to human biology — from the ability of H. sapiens to cope with environments outside Africa, to the tendency of modern humans to get asthma, skin diseases and maybe even depression.

In some cases, they are very different from the corresponding H. sapiens DNA, notes population geneticist David Reich of Harvard Medical School in Boston, Massachusetts — which makes it more likely that they could introduce useful traits. “Even though it’s only a couple or a few per cent of ancestry, that ancestry was sufficiently distant that it punched above its weight,” he says.

Using de-identified genome data and medical records from 28,000 hospital patients, [Corinne Simonti and Tony Capra, evolutionary geneticists at Vanderbilt University,] looked for differences in traits and medical diagnoses between people with a particular Neanderthal gene variant and those with the H. sapiens version of the same gene. They found that the Neanderthal variants seemed to slightly increase the risk of conditions such as osteo­porosis, blood-coagulation disorders and nicotine addiction. Another analysis, which looked at the combined effects of many DNA variants, painted a more mixed picture. It revealed links between Neanderthal DNA and depression, obesity and certain skin disorders, with some variants being associated with an increased risk and others with a reduced risk.