View of the cave in Siberia where the Neanderthal was found whose DNA was analyzed in the current study. (Credit:Bence Viola)
BOSTON, Jan. 29 (UPI) -- Modern humans are left with remnants of Neanderthal DNA that passed on genes associated with type 2 diabetes, lupus and smoking addiction.
Research led by Harvard Medical School geneticists has shown that modern humans with non-African ancestry share around two percent of their genome with Neanderthals. Previous studies have shown that Neanderthals interbred with humans around 40,000 to 80,000 years ago. As Neanderthals were present in Asia and Europe, indigenous Africans did not have ancestors who bred with Neanderthals.
“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,” said David Reich, professor of genetics and senior author of the paper. “We may also learn more about what Neanderthals themselves were like.”
Reich and colleagues at the Max Planck Institute for Evolutionary Anthropology in Germany analyzed the genetic makeup of 846 people of non-African ancestry, 176 from sub-Saharan Africa and a 50,000 year old Neanderthal. They found that certain parts of the non-African genome were abundant in Neanderthal DNA, possibly helpful for human survival, whereas other regions were devoid of any such DNA.
Areas of the genome barren of Neanderthal DNA were clustered into parts associated with the testes and with the X chromosome. According to researchers this shows signs of hybrid infertility, where the offspring of a male from one subspecies and a female from another have low or no fertility.
“This suggests that when ancient humans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility,” said Reich
Nine genetic variants associated with specific diseases have been linked to this mixture of DNA. These are related to immune function and behavioral traits, like the ability to stop smoking. Researchers expect additional research will link more genetic variants to Neanderthal DNA. Findings of this stay have been published in the journal Nature.
“I expect that this study will result in a better and more systematic understanding of how Neanderthal ancestry affects variation in human traits today,” said first author Sriram Sankararaman of Harvard Medical School.
[Harvard Medical School]