A new study states that passionate encounters between ancient humans and the Neanderthals may have left modern humans more prone to sneezes, itches and other allergies.
The study, which was conducted by the researchers from the Max Planck Institute for evolutionary Anthropology in Leipzig, and which was published in the American Journal of Human Genetics, states that Neanderthals and another ancient species, the Denisovans, not only interbred with modern humans, they did so frequently and successfully enough to give the present humans roughly 1 to 2 percent of our DNA.
Janet Kelso, from the Max Planck Institute for evolutionary Anthropology in Leipzig, and the lead author of the study, said, “Our Neanderthal and Denisovan legacy is something called innate immunity. This is our very early immune response. When the body detects that there is some foreign substance in the body, these are the guys that react immediately and it kind of calls in the big guns to fight off the virus, bacteria or other pathogen. A small group of modern humans leaving Africa would not carry much genetic variation. You can adapt through mutations, but if you interbreed with the local population who are already there, you can get some of these adaptations for free.”
The researchers explained that three genes are among the most common strands of Neanderthal and Denisovan-like DNA found in modern humans, suggesting they conferred an evolutionary advantage. They boosted the immune system, since the genes are involved in the body’s first line of defense against pathogens such as bacteria and fungi. However, people who carry the three genes seem to also pay a price in the form of an overly-sensitive immune system. They found that carriers of the genes were more likely to have asthma, hay fever and other allergies.
The researchers added that the modern humans inherited Neanderthal and Denisovan genes in three waves depending on where and when the groups met.
A separate study in France has made similar findings, which provides backing to Kelso and her team’s study.