Your risk of being diagnosed with depression may be influenced by caveman DNA

When it comes to mental health, there are so many factors: genetics, lifestyle, personal situations, you name it. But there’s a new (well, not literally new), shocking element that could influence your risk for depression: DNA inherited by our Neanderthal ancestors. Researchers recently discovered evidence that certain kinds of Neanderthal DNA can affect us in different ways. For example, one bit can influence our risk of tobacco addiction, while another can raise or lower our risk for depression.

So how does this work? Of course, our caveman ancestors were a much different people than we are now, but because ancestors of modern people interbred with Neanderthals about 50,000 years ago, approximately two percent of the DNA of those with Asian or European ancestry can be traced to Neanderthals. Doesn’t sound like much, but in the genetic spectrum, that two percent can have a major influence—and if scientists crack exactly what kind of influence it has, it can give them insight into many major diseases, evolutionary geneticist and senior author of the study Tony Capra said.

“For example,” Capra told NPR, “we found a specific bit of Neanderthal DNA that was associated with increased amounts of blood clotting.”

The researchers used bits of Neanderthal DNA that had been identified in prior studies and looked for its effect on medical records—and they found a bit of DNA that “was unusually common among people with depression,” according to NPR.

“If we looked at Neanderthal variants overall in an individual, we could better predict their risk for depression,” Capra told Newsweek said. However, Capra highlighted that this doesn’t mean our predecessors are “making us depressed.” “It’s that some bits of Neanderthal DNA increase your risk and other bits of Neanderthal DNA—your genome—decreases your risk,” he added.”

Another finding: A rarer bit of Neanderthal DNA can roughly double the risk of tobacco addiction. Capra explained that, since tobacco wasn’t available to Neanderthals, it’s hard to say if this had any effect on them—but it looks like it certainly does on us.

“Over the past 10 years or so, there’s been a revolution in our ability to read DNA from ancient fossils, and this has revealed some amazing things about recent evolution and human evolutionary history,” Capra said in a statement.

Only time—and science—will tell if our ancestor’s DNA will be able to help us crack the code to understanding hundreds of complicated diseases.