We often comfort people who are under stress by putting our arms around them and giving them a hug. According to recent research from scientists at Liverpool John Moores University, chimpanzees do the same thing.
The researchers found that chimps that had been involved in a conflict were often joined by a fellow chimp (usually a "friend" or family member) that would comfort the victim with two-armed embraces or kisses on the head and back. The fellow chimp’s gestures seemed to not only calm the victim but also reduce such stress behaviors as nervous scratching and self-grooming.
(Source: Associated Press)