Add Yahoo as a preferred source to see more of our stories on Google. Primatologist Susan Perry of UCLA has spent much of the past 35 years studying the complex social lives of white-faced capuchin ...

Male capuchin monkeys on a Panamanian island were documented carrying around infant howler monkeys for no clearly discernible reason. By Elizabeth Landau Capuchin monkeys don’t generally hang out with ...

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 ...

A capuchin named Joker started the apparent trend, leading researchers to suspect "there was something a little quirky about him, or that he was kind of lonely in a way.” Reading time 3 minutes A ...