Italian researchers have proven that imitative behavior as a form of social learning extends beyond our “great ape” cousins to our monkey cousins. They were able to get macaque monkeys to imitate facial expressions such as sticking out one’s tongue, and opening one’s mouth as early as just 2 days old.
Mimicry of adult facial expressions is the way babies learn such expressions, not being able to see their own faces. This imitation is also important in developing mother-child relationships.
Oh, who am I kidding? This is just an excuse to show monkeys. Go to the website for video.