Many animal species display facial expressions, but expressions are particularly developed in primates. In fact, some primates, such as chimpanzees, have complex facial expressions with many physical and functional similarities to humans. These are “critically important for coordinating social interaction, facilitating group cohesion and maintaining individual social relationships,” according to researchers at Emory University’s Yerkes National Primate Research Center.

 

Here’s a look at some of our favorite photos of expressive primates — from grumpy gorillas to spooked spider monkeys. (Text: Laura Moss)