Perhaps no form of communication sends a more vivid and direct message than that of touch. Whether used to extend a friendly greeting, to soothe or support, or even to intimidate, it is difficult to misinterpret the meaning of a tactile signal.
Like all primates, chacma baboons spend a significant amount of time expressing themselves through physical contact, from reassuring touches and pats to antagonistic bites and swats.
When two individuals meet, they will cordially touch muzzles and acknowledge each other in an amiable “nose-to-nose greeting.” Chacmas also engage in “social mounting,” which is generally a response to social presenting. Though it resembles a sexual mount, the baboon has no real intention to mate. In most instances, social mounting signals friendly reassurance, but it has been noted by primatologists to occur during aggressive encounters as well.
But the one form of physical expression held sacrosanct in chacma society is “social grooming.” In addition to the hygenic benefit of removing parasites, dead skin, and debris from the fur, grooming is also thought to reinforce social bonds between animals. For the baboon being groomed, the experience of having its hair pulled is highly pleasurable, as it releases endorphins that produce a natural high. This helps to alleviate stress and build trust among members of the troop. In fact, studies have proven that the levels of stress hormones, called “glucocorticoids,” drop significantly in chacmas after they engage in grooming behavior.