Overweight, depressed smoker? Blame your Neanderthal DNA

If you are a heavy smoker, overweight, depressed, and have survived a heart attack or stroke, it could be your Neanderthal ancestry that is to blame. Scientists have shown that Neanderthal DNA is more than just an interesting souvenir of inter-breeding between ancient human sub-species. It appears to influence around a dozen health-related traits - many of them not good. One specific genetic variant inherited from Neanderthals significantly increases the chances of being addicted to nicotine, the study found. Others influence the risk of depression, some making it more and some less likely. Yet another variant makes it easier for blood to coagulate, thereby raising the risk of heart attacks, strokes, lung clots, and pregnancy complications. People with "Neanderthal skin" are also less able to withstand the sun, leaving them vulnerable to a patchy, scaly skin condition called actinic keratosis that mostly affects fair, blue-eyed individuals. The US team made the discoveries after identifying 135,000 single-letter variations in the genetic code that were highly likely to have originated from Neanderthals. They then looked at how often these variants, known as single nucleotide polymorphisms (SNPs), appeared in the DNA of 28,000 Americans of European ancestry whose health records could be checked. Lead researcher Dr John Capra, from Vanderbilt University in Nashville, said: "Our main finding is that Neanderthal DNA does influence clinical traits in modern humans: We discovered associations between Neanderthal DNA and a wide range of traits, including immunological, dermatological, neurological, psychiatric and reproductive diseases." Our direct ancestors, early modern humans, are widely believed to have interbred with Neanderthals as they migrated out of Africa between 50,000 and 60,000 years ago. The Neanderthals, also derived from species that first evolved in Africa, had already occupied Eurasia for around 200,000 years. But by about 40,000 years ago they were extinct, probably after losing out to the brighter and more adaptable newcomers. Since 2010 scientists have known that between 1% and 4% of the DNA of people of Eurasian origin is inherited from Neanderthals. But just what impact it has had on human biology has been unclear until now. The new study, published in the journal Science, is the first to compare directly Neanderthal DNA from a significant population of adults of European ancestry with their clinical records. Researchers who carried out the work presented their findings at the American Association for the Advancement of Science (AAAS) annual meeting taking place in Washington DC. The investigation identified a large number of Neanderthal variants that were associated with psychiatric and nervous system effects including depression, mood disorders, and physical diseases with a neurological basis. Doctoral student Corinne Simonte, also from Vanderbilt University, said: "The brain is incredibly complex, so it's reasonable to expect that introducing changes from a different evolutionary path might have negative consequences."