Suomi – aggression in monkey play

Well, Rhesus monkeys, as they are growing up, as do most primates, engage in a great deal of play behavior during their juvenile years. This behavior takes a variety of forms and there are interesting gender differences that emerge very early, just as, that parallel gender differences that have been reported over and over again in studies of human play. In particular, males tend to engage in rough and tumble play; the monkey version of a wrestling match, if you will. Whereas female monkeys show much less contact in activities in their play and instead prefer chasing games and patterns of affiliation. So if you look at the play patterns, males not only play a little bit more than do females, they play more physically and more roughly.  

Also, very quickly on, these monkeys, when they’re in mixed-sex groups, begin to segregate themselves by gender in terms of their play partners. Basically it seems to be a consequence of the fact that a male will play with just about anything that moves whereas a female usually will not respond to a rough and tumble play initiate from a male but will readily respond to an initiate from a female. So basically females are choosing partners and males are left with only other males with whom to play. But the developmental course, emergence and developmental trajectory of these gender differences are virtually identical to what you see in human children if you take into account the fact that the monkeys grow up four times faster.