Sex Differences in Social Play

>Social Play is very common in mammals; in many species of bird; and in a few species of fish, reptile, and invertebrate (Burghardt, 2005). The most common form is play fighting, which typically involves chasing and rough and tumble components; the latter can include wrestling, muted biting, pouncing and jumping on partners, pushing, and so forth (Archer, 1992; Panksepp, Siviy, & Normansell, 1984; Powers, 2000; J.R. Walters, 1987). Play fighting typically involves pairs of evenly matched (e.g., in terms of size) individuals and increases in frequency from infancy to the juvenile years and then slowly declines, often merging into serious fighting by reproductive age. Play fighting includes many of the same components of intrasexual fighting or territorial defense but differs in enough ways to make a straightforward practice of fighting behaviors unlikely in most species (Pellis & Pellis, 2007). In fact, many of the basic behavioral components of species-species fighting are evident at birth, but their expression is often better controlled, more nuanced, and more varied for individuals that have engaged in play fighting. By enabling the development of better controlled and more flexible fighting skills, this form of play likely results in later social competitive advantage (Pellis & Pellis, 2007; P.K. Smith, 1982).

Unlike locomotor and object-oriented play, sex differences in play fighting are found in a wide range of species, with the form and intensity of this play closely tracking sex differences in the form and intensity of intrasexual competition and other agonistic behaviors in adulthood (Maestripieri & Ross, 2004; Power, 2000; P.K. Smith, 1982). Across species of marsupials (e.g., red kangaroos, Macropus rufus), pinnipeds (e.g., northern elephant seal, M. angustirostris), ungulates (S. ibex), rodents (Norway rat, Rattus norvegicus) and primates (e.g., chimpanzee, Pan troglodytes), Power found that males of polygynous species with intense physical male-male competition nearly always engaged in more play fighting during development than did conspecific females; these sex differences are not found in their monogamous cousins with less intense intrasexual competition (Aldis, 1975; P.K. Smith, 1982). Carnivores are the exception that seems to prove the rule. Intense competition over mates or food is the norm for males and females of most of these species, and both sexes tend to engage in play fighting during development. A notable exception among carnivores is the spotted hyena in which females compete fiercely with other females over food, are polyandrous, and are dominant over males (East, Burke, Wilhelm, Greig, & Hofer, 2003). In this species, females engage in more play fighting than males (J.M. Pederson et al., 1990).

Play parenting is one form of social play that is consistently more common in females than in males, although it can occur in both sexes (Nicolson, 1987; Pryce, 1993, 1995). When presented with an array of children's toys, G.M. Alexander and Hines (2002) found that female vervet monkeys (Cercopithecus aethiops sabaeus) carried and played with dolls much more than their brothers; their brothers engaged in more play with a ball and toy car. Hassett, Siebert, and Wallen (2008) found the same sex difference for rhesus macaques (Macaca mulatta). For primates in general, play parenting and general interest in infants is most frequently observed in young females that have not yet had their first offspring. For many of these species, play parenting (e.g., caring for siblings) is associated with higher survival rates of their first-born, and sometimes later born, offspring (Nicolson, 1987). Across five primate species it was found that first-born survival rates were two to more than 4 times higher for mothers with early experience with infant care obtained through play parenting than for mothers with no such experience (Pryce, 1993). Maternal behavior is also influenced by the hormonal changes that occur during pregnancy and the birthing process, such that a combination of play parenting and these hormones contribute to maternal skill in many primates (Pryce, 1995).<

David C. Geary; 2010
Male, Female - The Evolution of Human Sex Differences;