Genes inherited from ancient hominins have improved the human immune system.

Homo sapiens interbred with Neanderthals and other ancient humans called Denisovans less than 100,000 years ago. Janet Kelso and her team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, looked for Neanderthal and Denisovan genetic ancestry that has benefited humans by analysing the genomes of hundreds of people from around the world. They found a cluster of three Toll-like receptor (TLR) genes, which are involved in rapidly sensing and responding to infections as part of the innate immune response. Two Neanderthal versions of this cluster and one from Denisovans are common in different human populations. The archaic TLR genes are linked to reduced susceptibility to a bacterial infection of the stomach, but also to higher rates of allergies.

In a separate study, a team led by Lluis Quintana-Murci at the Pasteur Institute in Paris identified innate immunity genes that Europeans and Asians seem to have inherited from Neanderthals, including the same cluster of TLR genes.

Am. J. Hum. Genet. http://doi.org/bbn3 (2016); http://doi.org/bbn2 (2016)