Got health problems? Blame it on Neanderthal DNA

BY Rebecca Jacobson  January 29, 2014 at 6:35 PM EDT

Geneticists have found that Neanderthals passed on genetic traits to modern day humans that may explain immune diseases and other traits. Photo courtesy of Flickr User Matt Celeskey.

If you are suffering from type 2 diabetes, Crohn’s disease, lupus, biliary cirrhosis, or you simply can’t kick your smoking habit, you may be able to blame your Neanderthal ancestors.

Harvard Medical School geneticists have been looking at which helpful and harmful genetic material present-day humans inherited from our distant Neanderthal cousins. Their findings were published Wednesday in Nature.

On average, people with no African ancestry can trace about two percent of their genome back to Neanderthals, a species of early human who lived in Europe and Asia 40,000 to 80,000 years ago.

“Now that we can estimate the probability that a particular genetic variant arose from Neanderthals, we can begin to understand how that inherited DNA affects us,” David Reich, professor of genetics at Harvard Medical School and senior author of the paper, said in a press release. “We may also learn more about what Neanderthals themselves were like.”

Reich and his colleagues collaborated with scientists at the Max Planck Institute for Evolutionary Anthropology in Germany. They studied genetic variants in 846 people of non-African heritage, 176 people from sub-Saharan Africa, and compared their genomes to a 50,000-year-old Neanderthal.

They found that Neanderthal DNA has an influence on keratin production, a protein that makes our hair, skin and nails thick and tough. Neanderthal’s likely adapted those traits and by passing them on, helped Homo sapiens survive colder climates. But they also found nine previously identified human genetic variants associated with specific traits from Neanderthals. These variants affect diseases that are related to immune function — including type 2 diabetes or Crohn’s disease — and behaviors, such as the ability to stop smoking.

Scientists will need to study other Neanderthal DNA to better understand our human genome ancestry, but they suspect that variation in other human traits have Neanderthal origins as well. They are also studying genome sequences from people in Papua New Guinea to compare to Denisovan DNA, another population of ancient humans that lived in Oceania and in parts of mainland Eurasia.

“The story of early human evolution is captivating in itself, yet it also has far-reaching implications for understanding the organization of the modern human genome,” Irene A. Eckstrand of the National Institutes of Health’s National Institute of General Medical Sciences said in a press release. “Every piece of this story that we uncover tells us more about our ancestors’ genetic contributions to modern human health and disease.”

For more on our ancient DNA history, you can read NewsHour’s December report on the oldest known human DNA.

H/T Rebecca Jacobson