You Probably Have Allergies Because Your Ancestors Had Sex With Neanderthals

Time for a science lesson on interbreeding and immunity.
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Time for a science lesson on interbreeding and immunity.

According to two new studies published in the American Journal of Human Genetics, modern allergies for many people are likely a byproduct of interspecies sex between Homo sapiens and the ancient Hominids, Neanderthals and Denisovans.

Congratulations, you probably have your runny nose because your human ancestors got freaky with cavemen.

Before you go off on how much you hate whoever cursed you with hives and a watery eyes, be proud of your ancestors, because finding flat, tiny heads and wooly unibrows sexy is pretty hardcore.

Neanderthals and Denisovans — a now extinct Hominid – lived in Europe and Central Asia about 200,000 years before Homo sapiens, a.k.a. humans, showed up. By the time humans arrived and started having sex with everyone, the Neanderthals and Denisovans had been living in the area for so long that they were immune to the local pathogens. The newcomers were not.

So, ancient Hominid DNA + Homo sapien DNA = ugly babies and allergies. However shitty allergies may seem, the interspecies breeding actually led to some amazing gene variation, making for some seriously strong immune systems. The allergies were just an unfortunate side-effect.

“Increased resistance to bacterial infection was advantageous, but may have resulted in some increased sensitivity to non-pathogenic allergens,” said Janet Kelso in a press release via Cell Press. Kelso is a researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and senior author of one of the studies. "I suppose that some of us can blame Neanderthals for our susceptibility to common allergies, like hay fever," she continued.

Through human DNA collected by the 1,000 Genomes Project, scientists from both studies were able to identify three specific genes from Neanderthals and Denisovans that make up part of the human body’s innate immune response to bacteria and viruses- TLR6-TLR1-TLR10. "When the body detects that there is some foreign substance in the body, these are the guys that react immediately," as Kelso puts it.

The studies found that about 2% of the DNA in most people came from Neanderthals and Denisovans, and that in some European and Asian groups, the three ancient Hominid genes can be found in 50% of the population, making them super immune, but also probably super allergic.

The researchers reported that the genetic variation that came from interbreeding helped early humans survive when they left Africa. “The things we have inherited from Neanderthals are largely things that have allowed us to adapt to our environment,” Kelso said. “This is perhaps not completely surprising.”

There is still a lot of research to be done about Neanderthals and genetics, but now you know that if someone calls you a Neanderthal as an insult, they’re actually calling you a very healthy sex machine, so joke’s on them.