In fact, outside of a few special relationships such as between spouses or parents and children, and except for ritual greetings such as handshakes, we seldom touch one another at all. Certainly we never spend hours each day picking carefully through the hair of even our kids, far less our friends and neighbors. Instead, Robin Dunbar argues in Grooming, Gossip, and the Evolution of Language , we gossip. Just as grooming acts to cement social relationships between individual primates, so does gossip cement social relationships between individual humans. Dunbar's argument is fairly straightforward.
Grooming is the tie that binds the individuals in social groups of primates.
But grooming is time-consuming, stealing precious hours from foraging for food, watching for predators, and other important activities. Finally, there is a direct relationship between time spent grooming and group size. In primate species with the largest social groups of 50 to 55, such as chimpanzees and baboons, grooming may occupy as much as 20 percent of each animal's day. Talking has a two-fold efficiency advantage over grooming. First, we can talk and do other things, like look for food, at the same time.