Imagine watching a video of a chimpanzee. The ape pulls its lips back in a wide, playful grin. Without realizing it, the ...

This video shows a monkey approaching a human and holding the person's leg while looking for food. The monkey stays close and waits, showing its reaction and behavior while expecting something to eat.

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. Primates have larger brains ...

This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated. The 43 rhesus macaque monkeys that escaped a ...

A new study shows macaque species with more tolerant social systems have larger brain regions linked to emotions and social signals.