“Nature teaches beasts to know their friends,” wrote
Shakespeare. In humans, nature may be less than half of the story, a team led
by University of Colorado Boulder researchers has found.
In the first study of its kind, the team found that genetic
similarities may help to explain why human birds of a feather flock together,
but the full story of why people become friends “is contingent upon the social
environment in which individuals interact with one another,” the researchers
write.