The fact that an animal would risk injury on behalf of another, even though they are not related, suggests that these friendships are extremely important to the animals, Moscovice says. Platt and his group, who study animals in the wild as well as in the lab, recently initiated a large-scale study to look at temperament, as well as genetic and other individual characteristics, in a population of rhesus macaques on an island just off the coast of Puerto Rico. Studying the biological mechanisms that come into play as animals cooperate, says Moscovice, may help explain how the capacity for friendship and social behavior arose and endures among humans.