Dunn’s team analyzed the biological “budget” of these primates and found a direct negative correlation: males with large ...

Howler infant number 5 on the back of a juvenile capuchin carrier, who is using stone tools at an anvil site in a stream bed. CREDIT: Brendan Barrett / Max Planck Institute of Animal Behavior. Get the ...

On an island in Panama, a fad that one researcher called "viscerally disturbing" has recently taken off among a group of young male monkeys. These adolescents and juveniles have started to kidnap the ...