Researchers determine that a primate’s tooth root, and not just its crown, can yield reliable information about body size, but the relationship between root surface area and diet isn’t as clear.

This gives them advanced learning and problem-solving abilities. Many primates also live in complex social groups and communicate through vocal sounds, body language and facial expressions. Humans' ...

But our earliest primate ancestors lacked this ability ... The shared origin of these body parts is reflected in their strikingly similar development. They also share a common set of genetic ...