Do you suffer from allergies? You can thank your distant ancestors for that. According to scientists, pre historic interbreeding between early humans and Neanderthals 500,000 years ago could have resulted in modern allergies.
The theory, detailed in the American Journal of Human Genetics, states that unusual genes that can cause allergies were likely passed on to early humans when they bred with Neanderthals and Denisovans. These two subspecies had been living in Europe and western Asia for hundreds of thousands of years before modern humans showed up—giving them ample opportunity to adapt to the local pathogens.
A new study in Science also revealed that a study of 28,000 Americans shows that these gene variants can raise the risk of depression, skin lesions, blood clots, and other disorders.
“Studies like ours help to better understand the sources contributing to patterns of human genomic diversity,” Joshua Akey commented.
When humans bred with these local species, they picked up genes that made them resistant to these pathogens as well. Now, a team from the Max Planck Institute for Evolutionary Anthropology in Germany found three of these genes that still play a role in human ‘innate immunity,’ impacting the important mechanisms in our system that immediately react to infections.
At the time, these genes provided great benefit, giving humans the ability to travel throughout the world and colonize new areas without being made extinct by diseases. Today, however, they create problems for the people who still carry them. These genes are quick to react to harmful pathogens, but this protective system can also cause the immune system to overreact to things like pollen or animal hair.
“I suppose that some of us can blame Neanderthals for our susceptibility to common allergies, like hay fever,” Janet Kelso from MPI told NPR.
The researchers also found a number of Neanderthal genes associated with neurological conditions, including depression, which can be triggered by disturbances to circadian rhythms. Capra believes that Neanderthal brain chemistry and their skin responses to sunlight may have been better suited to the light conditions and lifestyles of prehistoric Europe. The gene variants responsible may not adapt well now that most people live by artificial light.
Source: Science Magazine