What Percent Neanderthal Are You?

Personalized genetic testing is booming. People are curious about their genomes, and genetic testing offers a peek into our past, and a look at what might be waiting for us, biologically speaking, down the road.

Popular genetic testing service 23andMe can even show you what percentage of your DNA is Neanderthal. Since 2010 we’ve known that trace amounts of Neanderthal DNA made it into the gene pool (it’s not hard to figure out how), and this spurred a rash of hypotheses about what effects this pre-historic DNA could be having on modern biology. But up until now these have only been hypotheses and actually knowing what percentage of your DNA is Neanderthal is mostly a cool factoid, rather than a useful piece of information.

But now, thanks to researchers from Vanderbilt University in Tennessee, we have a much clearer picture of the impact on Neanderthal DNA on our health.

Source: Deborah Brewington / Vanderbilt University

To be clear, Neanderthals aren’t pre-historic Homo sapiens—they didn’t evolve into us. We share a genus (Homo) and about 99.5% of our DNA, but they were a different species, physically much stockier than Homo sapiens, with bigger muscles and even bigger brains.

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But although they died out long ago, modern people of Eurasian descent can have anywhere from one to four percent of their DNA in common with Neanderthals.

And now a team of evolutionary geneticists has published a study in the journal Science that directly compares the genomes of adults of European descent (with Neanderthal DNA) with clinical records—the first study to do so.

Their findings indicate that Neanderthal DNA does have a significant impact on modern human biology. It can affect the skin’s reaction to sunlight, increase the risk of nicotine addiction, and even influence depression and other psychiatric factors.

“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,” said John Capra, senior author of the paper.

To carry out the research, the team used a database of biological samples from 28,000 patients linked anonymously with electronic health records.

According to a press release from Vanderbilt University, the data came from the Electronic Medical Records and Genomics Network—otherwise known as eMERGE—which funded by the National Human Genome Research Institute.

The data allowed the researchers to identify specific medical conditions like depression in each individual and then analyze the genomes in order to identify the sets of Neanderthal DNA that were present.

The research paints a clear picture of which Neanderthal DNA sets are associated with specific conditions, and could be a key piece in the story of human evolution.