A second Neanderthal genome has now been fully and carefully sequenced, and she’s a beaut. Scientists reported on Thursday that the DNA from the woman, whose 52,000-year-old remains were discovered in a cave in Croatia, suggests she was more closely related to the Neanderthals who mated with the ancestors of today’s Europeans and Asians than was the only other Neanderthal to be fully sequenced, a man from southern Siberia.
That means her genetic variants are more likely to be in people today. Here’s what you need to know to sound knowledgeable about your Neanderthal genes, should someone make any cracks about your posture:
How much Neanderthal do I have in me?
That depends on your family roots. If you’re from sub-Saharan Africa, zero: Neanderthals, who inhabited Europe, mated only with Homo sapiens who left humankind’s ancestral continent some 100,000 years ago. They’re therefore ancestors only of non-sub-Saharan Africans. If you’re East Asian, you’re about 2.3 percent to 2.6 percent Neanderthal. If you’re from Western Eurasia, approximately from central Russia to points west, your genome is 1.8 percent to 2.4 percent Neanderthal. That range of 1.8 percent to 2.6 percent compares to previous estimates of 1.5 percent to 2.1 percent.
I’m guessing that includes genes that make my brother-in-law really hairy.
Probably not. DNA from the southern Siberian chap and three other Neanderthals whose DNA was partly sequenced previously showed that modern humans carry Neanderthal genes involved in depression, being overweight, getting skin damage from sunlight, catching serious upper respiratory tract infections, developing atherosclerosis, lipid metabolism, diabetes, and immune defense against bacteria and parasites.
But wait, there’s more?
Yes, the genome from the Croatian Neanderthal adds to that list, biologists led by ancient-DNA whiz Svante Pääbo, of Germany’s Max Planck Institute for Evolutionary Anthropology, reported in Science.
Thanks to Neanderthals’ long-ago couplings with our ancestors, some modern humans inherited a DNA variant associated with blood levels of the “bad” LDL cholesterol. (The variant is called rs10490626, and it’s in a gene called INSIG2, for those of you who want to ask your friendly neighborhood DNA sequencer to check for it.) Another Neanderthal gene is associated with vitamin D (the rs6730714 variant of the PAX3 gene).
There are also variants associated with eating disorders, visceral fat accumulation, rheumatoid arthritis, schizophrenia, and the response to antipsychotic drugs.
A separate study, in the American Journal of Human Genetics, took a somewhat different approach. It compared DNA from the Siberian Neanderthal to genetic data on 112,338 participants in the UK Biobank study, which records participants’ genetic data, physical traits, disease, and more. Janet Kelso and Michael Dannemann, also of the Max Planck Institute, got 15 matches: Neanderthal variants are associated with skin tone (either light or dark, depending on the variant), hair color, how easily a person tans and whether they had sunburns in childhood, height, and a high resting pulse rate. Note to artists: the Neanderthal had zero genes for red hair color.
So if I have arthritis or a fast heartbeat, I can blame my great-great-great … Neanderthal grandparent?
Not necessarily. The arthritis variant raises your risk of that disease by a piddling 14 percent, so lifestyle factors and other genes not from Neanderthals play a role, too. The schizophrenia variant raises the risk of developing that disease sixfold, though, at least according to a small 2009 study.
Wait. Why would evolution not have eliminated bad variants from the human gene pool?
First of all, studies linking genes to traits sometimes turn out to be wrong, so it’s possible Neanderthal variants that seem harmful might actually do something else, or something additional, that’s either beneficial or neutral. The researchers didn’t investigate the function of the new genes they identified in Ms. Croatia; they just checked her DNA sequences against databases, which can be incomplete or incorrect.
To state the obvious, Neanderthals weren’t taking Ativan, so a genetic variant that influences the brain’s response to antipsychotic drugs must have had, and probably still has, an additional function. And maybe seemingly harmful variants such as that for schizophrenia have stuck around because they also confer benefits — perhaps it made those who carry it more creative, a useful trait to have when you’re battling mammoths and ice ages.