Interbreeding Between Modern Humans and Evolutionary Cousins Gave Healthy Immune System Boost to Human Genome
For a few years now, scientists have known that humans and their evolutionary cousins had some casual flings, but now it appears that these liaisons led to a more meaningful relationship.
Sex with Neanderthals and another close relative — the recently discovered Denisovans — has endowed some human gene pools with beneficial versions of immune system genes, report researchers at the Stanford University School of Medicine in an article to be published online by the journal Science at the Science Express website on Aug. 25.
Although modern humans, Neanderthals and Denisovans share a common ancestor in Africa, the groups split into separate, distinct populations approximately 400,000 years ago. The Neanderthal lineage migrated northwestward into West Asia and Europe, and the Denisovan lineage moved northeastward into East Asia. The ancestors of modern man stayed in Africa until 65,000 years or so ago, when they expanded into Eurasia and then encountered the other human-like groups. In some cases, the rendezvous were amorous in nature.
Laurent Abi-Rached, Paul Norman and Libby Guethlein are co-authors of research on how the genome of geographically-distinct human populations vary in the amount and type of immune-system genes inherited from evolutionary cousins, the Neanderthals and Denisovans. People in Papua New Guinea, for instance, have a particularly high percentage of one type of immune-system gene that is rarely found in people in Africa. (Credit: Norbert von der Groeben)