Advertising

About 40,000 years ago, when humans roamed Earth alongside Neanderthals and Denisovans (another now-extinct species), there was some inter-species breeding going on between these three species that influenced Homo sapiens sapiens as they exist today.

To this day, people whose family history extends beyond Africa have between 1-6% DNA overlap with Neanderthals or Denisovans. Two studies published in the American Journal of Human Genetics show that these other species in the Homo genus gifted humans with three genes related to the immune system. These genes, researcher Janet Kelso told NPR, provide humans' "very early immune response."  

Easy to see what humans saw in Neanderthals.
Easy to see what humans saw in Neanderthals.
Sources: The Guardian | NPR