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 ...

Wild capuchin monkeys have been kidnapping infant howler monkeys, putting them on their backs and taking them for a ride. The trend, which began with one male, spread to other members of the group, ...

A young male nicknamed Joker was probably the first to start carrying a howler monkey baby on his back for days on end. Then a group of other young males started to copy him. Here a white-faced ...