Are You Part Neanderthal?
Depending on your ancestry, there might be a little bit of Neanderthal in you. About 2 percent, actually. That’s the percentage of Neanderthal DNA that geneticists estimate non-African individuals possess, due to ancient interbreeding.
There was a time—about 40,000 years ago—that Neanderthals and our human ancestors coexisted. Neanderthals died out, but they had interbred with humans, transferring a healthy dose of their DNA. (This archaic genetic mingling applies only to those with non-African heritage because Neanderthals and humans did not coexist in Africa.)
Rajiv McCoy, an assistant professor in the Department of Biology, says research has shown that possessing a Neanderthal copy of certain genes has been associated with variation in traits such as height or with the chance of getting certain diseases, such as schizophrenia. “These effects tend to be small overall,” says McCoy, “but they’re robust and significant.”
McCoy explores the molecular mechanisms that cause these associations to occur. He has looked at how genetic sequences inherited from Neanderthals might be influencing gene expression—the process by which information stored in our DNA is converted into instructions for making proteins or other molecules.
In a recent study, McCoy and his colleagues used data collected from tissue samples to determine whether a person had inherited a Neanderthal gene and a modern human version of the same gene (one from the mother and one from the father). They then compared the gene expression levels between the two copies of that gene. What they found was that in about a quarter of the genes they tested, there indeed was a difference—depending on the specific gene—in expression levels between the Neanderthal copy of the gene and the modern human copy of the gene. This observation informs us about the mechanisms of gene regulation that caused traits to diverge during human evolution.
A related line of research, which McCoy says would not have been possible just five years ago, involves searching for larger structural differences between the genomes of modern humans and Neanderthals. These include thousands of base pair stretches of inserted, deleted, or rearranged DNA sequences. “Due to technological advances, we’re able to see tons of structural variations [at the molecular level],” he says. McCoy believes that the new technology will reveal more clues about our genetic relationship to our Neanderthal cousins.