Chimpanzees strengthen friendships by spending extensive time grooming each other. Humans spend a comparable time socializing, albeit more through talking than grooming. Nevertheless, much of the vast amounts of inconsequential chatter we produce is simply a more sophisticated version of chimpanzee grooming – it serves little other purpose than to strengthen our relationship bonds. Humans also demonstrate stronger relationships through physical contact – a pat on the back, a hug, or a friendly shove. Primate social group sizes closely reflect their brain sizes. Chimpanzees have about 50 close friends and acquaintances, whereas humans have between 150 and 200.