A 2014 study found that friends could be a kind of "functional kin," sharing certain genotypes with each other to gain an evolutionary benefit. The study examined the genes of almost 2,000 people, comparing friend pairs with stranger pairs, and found that on average, friends had more genes in common than strangers did. Genes that related to the sense of smell were particularly likely to be shared between friends, whereas those related to immunity tended to have less overlap.
Written by Curiosity Staff December 30, 2015
Wake up with the smartest email in your inbox.
Our Best Articles Daily