You may blame your mom and dad for certain genes, but a new study out of Vanderbilt University has found that you might need to go back a few thousand years for the real culprits—Neanderthals.
For a long period of time, it was uncertain if Homo sapiens had interbred with Neanderthals at all, but in 2010 it was discovered that people of Eurasian origin inherited 1 to 4 percent of their genes from them.
Even with this knowledge, though, we were not entirely sure how this DNA affects us—but now, first time ever, researchers have directly compared the Neanderthal gene groups (also known as haplotypes) to the DNA and health records adults of European ancestry—28,416 of them, to be precise.
Their results, which were published today in Science, identified 135,000 “high-confidence” genetic variations (known as SNPs, or variations of just one DNA building block somewhere in the genome) that are shared between Neanderthals and modern humans—and these variations indicate that Neanderthal genes have a subtle yet significant effect on the biology of modern humans.
“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, assistant professor of biological sciences at Vanderbilt University and senior author of the paper, in a statement.
Detrimental in the West
These variations now seem to be largely detrimental to humans, but it probably wasn’t always this way.
“It is possible that some Neandertal alleles provided a benefit in early AMH [anatomically modern human] populations as they moved out of Africa, but have become detrimental in modern Western environments,” wrote the authors.
Credit: Deborah Brewington, Vanderbilt University
Now, though, this shared genetic material has been linked by these researchers to an increased likelihood of health issues such as heart attacks, obesity, hypercoagulation (too much blood clotting), UTI, and callouses in modern humans.
Moreover, they confirmed a previously-held hypothesis that Neanderthal DNA leads to solar keratosis—which consists of skin lesioning caused by exposure to the sun’s UV rays. Apparently, the DNA from Neanderthals affects the cells in the skin that help protect it from various types of damage, including that from the sun—meaning that skin is less protected and thus can be harmed.
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The results also showed that Neanderthal DNA affects your chances of having depression—although, depending on the variations you receive, it can make you either more or less likely than the average human to develop the disorder. Mood disorders in general were shown to have an increased likelihood for those with Neanderthal DNA.
Perhaps most surprisingly, though, the Neanderthal DNA has now been tied to a significant risk of developing a nicotine addiction. The variation in question actually affects signaling in the brain associated with a neurotransmitter called GABA—which is linked to an increased smoking risk.
“The brain is incredibly complex,” said Vanderbilt doctoral student and first author Corinne Simonti, “so it’s reasonable to expect that introducing changes from a different evolutionary path might have negative consequences.”
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Feature Image: Thinkstock
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