Social grooming
Social grooming is a behavior in which social animals, including humans, clean or maintain one another's bodies or appearances. A related term, allogrooming, indicates social grooming between members of the same species. Grooming is a major social activity and a means by which animals who live in close proximity may bond, reinforce social structures and family links, and build companionship. Social grooming is also used as a means of conflict resolution, maternal behavior, and reconciliation in some species.[1][2] Mutual grooming typically describes the act of grooming between two individuals, often as a part of social grooming, pair bonding, or a precoital activity.
This article is about the social activity. For other uses, see Groom (disambiguation).Ontogeny of social grooming[edit]
General learning and reciprocation of allogrooming[edit]
In most cases, allogrooming is an action that is learned from an individual's mother.[39] Infants are groomed by their mothers and mimic these actions on each other and the mothers as juveniles. This action is reciprocated on other group members (non-mother or of a different rank) more often once the individual is a fully developed adult and can follow normal grooming patterns.[39]
Sex-based differences in learning[edit]
Male and female members of a species may differ in learning how, when, and whom to groom. In stump-tailed macaques, infant females mimic their mothers' actions by grooming their mothers more often than their male counterparts do and by grooming the same group members that their mothers groom.[40] This mimicry is suggested to indicate identification-based observational learning in infant stump-tailed macaques, and the daughters' penchants for maternal mimicry and kin-biased grooming versus the sons' penchants for rank-biased grooming falls in line with their social roles in groups, where adult males require alliances in order to gain and maintain rank.[40]
Tool usage[edit]
In nearly all instances of social grooming, individuals use their own body parts, such as hands, teeth, or tongue, to groom a group member or infant. It is very rare to observe instances of tool usage in social grooming in non-human animals; however, a few such instances have been observed in primates. In a 1981 observational study of Japanese macaques at Bucknell University, a mother macaque was seen to choose a stone after observing several stones on the ground, and then use this stone to groom her infant.[41] It was hypothesized that the stone was used as a distractor for the infant so that the mother could adequately clean him while his attention was occupied elsewhere. This was supported by the fact that the infant picked up the stone once the mother dropped it and allowed her to groom him while he played with it. This behavior was seen in a few other members of the colony, but not seen throughout the species. In another instance, a female chimpanzee at the Delta Regional Primate Research Center created a "toothbrush" by stripping a twig of its leaves, and used this toothbrush to groom her infant over several instances.[42] However, both examples concern tool use in primates, which is already widely studied and scientifically backed.[43] The wide working memory capacities and causal understanding capabilities of primates permit them to fashion and utilize tools far more extensively than other non-human animals.[44] Apart from physical and mental constraints, perhaps a reason allogrooming animals do not use tools is because a major purpose of social grooming is social bonding and involves emotional exchanges, much of which is conveyed by touch.
Criticism for studies quoted[edit]
Above all, the main criticism regarding studies concerning social grooming is that almost all of them focus on primates, and a narrow range of species within primates themselves. As a result, the literature does not provide a well-rounded idea of what the cognitive or behavioral basis for social grooming is, nor does it completely outline all of its effects, positive or negative. Even in well-studied species, it may be that not all the data relevant to social grooming has been collected.[11] Secondly, data for most species is derived based on the members of a single group. In primates, whose behavior is highly flexible depending on the socio-environmental conditions, this poses a particular challenge. Thirdly, most studies are short-term and observational, so the direct link between social grooming and fitness or mate choice outcomes cannot be studied directly as in long-term direct or captive studies.
