Have you ever gone to the zoo and observed the monkeys picking each other? This is a well-documented, long-studied, instinctive behavior in primates (monkeys, apes, etc.) called the grooming response.

Breakthroughs, discoveries, and DIY tips sent every weekday. Terms of Service and Privacy Policy. Holding hands isn’t just for human sweethearts. Chimps often ...

Kissing is a big part of human culture. According to ancient cuneiform tablets found in Iraq, humans have been smooching since at least 2500 B.C. Around the world today, many societies share kisses in ...