In 1960' s studies of rats, scientists found that crowding increases the number of attacks among the animals significantly  But in recent experiments in which rhesus monkeys were placed in crowded conditions, although there was an increase in instances of coping behavior-such as submissive gestures and avoidance of dominant individuals-attacks did not become any more frequent
Ttherefore it is not likely that, for any species of monkey, crowding increases aggression as significantly as was seen in rats
Some of the coping behavior displayed by rhesus monkeys is similar to behavior rhesus monkeys use to bring to an end an attack that has begun.