Ancient members of our species had sex with Neanderthals. That lineage contributes to 1–3% of the DNA in almost everyone outside of sub-Saharan Africa today. This much we know. When, where, and how often is a bit more murky. Studies published this year have narrowed down the timeframe of this interbreeding event to between 50,000 and 60,000 years ago in the Middle East; others say that it was about 37,000 to 42,000 years ago in Europe. And at least one study found evidence for more than one pulse of Neanderthal gene flow.
Regardless of the timing and location, researchers around the world are using large genomics studies to unravel the contributions that these ancient intermixing events made to our biology, Nature News reports. As it turns out, from our risk of developing a nicotine addiction to our chances of getting a stomach ulcer... their effects on our genomes were big.
Vanderbilt University’s Corinne Simonti and Tony Capra looked for differences between people who carry a particular Neanderthal gene variant and people with our species’ version of the same gene. The Neanderthal variants, they found, appeared to increase the risk of osteoporosis, blood-coagulation disorders, and addiction to nicotine. When the effects of many DNA variants were combined, they found links between Neanderthal DNA and depression, obesity, and certain skin disorders, including sun-triggered lesions. It’s important to note that while some variants were associated with an increased risk, others were linked with a reduced risk.
Meanwhile, a team led by Michael Dannemann from the Max Planck Institute for Evolutionary Anthropology found that many humans have Neanderthal versions of genes that code for proteins called toll-like receptors. These proteins help to initiate the body’s immune response when they sense pathogens. Human cells that contain the archaic versions tend to express these proteins at higher levels than cells carrying the Homo sapiens versions. While some of these archaic versions have been linked to a reduced risk of H. pylori infection (which can cause ulcers), other variants have been linked to higher rates of developing allergies.
These findings were presented at the Society for Molecular Biology and Evolution meeting in Vienna earlier this month.
[Via Nature News]