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David Geary Ph.D.
David Geary Ph.D.

Boys’ and Girls’ Culture

Evolutionary perspective on friendships.

The social and economic worlds (e.g., division of labor) of men and women tend to be segregated in many ways in traditional cultures. One result is that women and men need a different mix of social, behavioral, cognitive, and physical skills to be successful in these different worlds. One evolved function of the childhood and adolescent years is to refine and adapt this mix of skills to the local group and culture. Much of this adaptation occurs in the context of same-sex social groups, where boys and girls learn to cope with same-sex social dynamics and engage in the sex-typical activities of the adults in their culture.

Thus, it is not surprising that when there are enough boys and girls in the local area, children segregate into boys’ and girls’ groups. The segregation occurs independent of adult interventions and even in societies in which women’s and men’s social and economic worlds overlap much more than they do in traditional contexts. In fact, the formation of same-sex play and social groups is one of the most consistently found features of children’s behavior. Children begin to form these groups before they are 3 years old and do so with increasing frequency throughout childhood. In a longitudinal study of children in the United States, Maccoby and Jacklin (1987) found that 4- to 5-year-olds spent 3 hours playing with same-sex peers for every single hour they spent playing in mixed-sex groups. By the time these children were 6- to 7-years-old, the ratio of time spent in same-sex versus mixed-sex groups was 11:1. The same pattern has been documented in Canada, England, Hungry, Kenya, Mexico, the Philippines, Japan, and India, although the degree of segregation varies across these societies. In many traditional contexts where there are fewer potential playmates, children often play in mixed-age and mixed-sex groups but their core friendships still tend to be segregated by sex.

The different play and social styles of girls and boys contribute to the segregation. Girls and boys not only play differently, they use different social strategies to get what they want (e.g., toys) and to influence other children. More often than not, boys gain access to a desired toy by playfully shoving and pushing other boys out of the way, whereas girls gain access by means of verbal persuasion (e.g., polite suggestions to share) and sometimes verbal commands (e.g., “It’s my turn now!”). Maccoby (1998) concluded that the sex differences in play and social styles contribute to segregated social groups because children are unresponsive to the styles of the opposite sex. Boys sometimes try to initiate rough-and-tumble play or play fighting with girls but most girls withdraw from these initiations, whereas most other boys readily join the fray. Girls often attempt to influence the behavior of boys through verbal requests and suggestions but boys, unlike most other girls, are generally unresponsive; many readers are probably wondering whether boys ever become responsive–they do by adulthood, somewhat.

There is also peer pressure to avoid the opposite sex, especially among boys. This includes things such as teasing about “cooties” (an early sexually transmitted disease, apparently) if one interacts with a member of the opposite sex. In short, the differences in play and social styles result in children forming groups based on mutual interests and the ability to influence group activities, and one result is the formation of largely same-sex social networks.

The net result of sex segregation is that boys and girls spend much of their childhood in distinct peer cultures. It is in the context of these cultures that differences in the social styles and preferences of girls and boys become larger and congeal into patterns that they will take into adolescence and adulthood. In these contexts, they are learning to navigate social relationships, but largely relationships with same-sex, not opposite-sex peers. In contexts in which most core relationships in adulthood are with same-sex peers, this is not a major issue but can become an issue in contexts where there is much less segregation by sex–people haven’t learned how to read and respond to members of the opposite sex, often leading to miscommunication and frustration.

This is certainly an on-going concern in the modern world, where most workplaces are mixed-sex. There is also the deeper question of why girls and boys, when they have the opportunity, form different cultures and how these benefit them, at least in the contexts in which we evolved. The bottom line is that boys organize themselves into large groups in which all members know and often like another other and they act in concert to achieve shared goals, often in the context of competing with other groups of boys. These large social groups are consistent with an evolutionary history of group-level male-male competition noted in a previous post [Men’s Struggle for Status and Relevance], and their formation during development provides boys with ample opportunities to learn how to coordinate their activities before the competition becomes serious and often life-threatening. Girls, in contrast, organize themselves into emotionally-close dyadic relationships or a small network of relationships, whereby the best friends know a lot about each other (more than boys know about their best friend) and thus are well-positioned to provide emotional and social support when it is needed. In adulthood, these intensely supportive relationships provide an important buffer in dealing with the stressors of children, husbands, and other issues.

In other words, an evolutionary history group-level male-male competition shaped boys’ social development and the benefits of close, supportive interpersonal relationships shaped girls’ social development. But, why don’t boys and men also form these close interpersonal relationships, if they are so beneficial?

In an earlier article, my colleagues and I proposed that the sex differences in social relationships are related in part to the cost-benefit trade-offs associated with the formation of large, competitive coalitions as contrasted with emotionally supportive dyads (Geary et al., 2003). When it comes to coalitional competition, size matters: across species, larger coalitions have a competitive advantage over smaller ones. One result is that the often high-intensity demands of adolescent girls’ and young women’s friendships limit the number of these relationships (you can have only so many BFFs); the many benefits of girls’ and women’s friendships (e.g., intense social and emotional support) are traded for fewer of them. The formation of the larger social networks that are common among boys and men could only be developed and maintained by relatively low-cost activities, such as coordinated efforts to achieve a common goal (e.g., winning a sporting competition), or engagement in some form of rough-and-tumble play or playing fighting.

This is why a group of five men can watch a football game on television and not say much of anything personal to one another and yet feel bonded by the end of the game (especially if their team wins). Five women sitting together for three hours, watching television, and not enquiring about the well-being or personal life of the others would have a different outcome (e.g., beliefs that one or several of the women are upset with one another). These fundamental differences in how boys and men and girls and women form stable relationships, compounded by segregated social lives during development, contribute to many misunderstandings and frustrations in relationships with the opposite sex. A better understanding of how the other sex develops and maintains relationships and why they have these biases should go a long way toward reducing these misunderstandings.


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Geary, D. C., Byrd-Craven, J., Hoard, M. K., Vigil, J., & Numtee, C. (2003). Evolution and development of boys’ social behavior. Developmental Review, 23, 444-470.

Maccoby, E. E. (1998). The two sexes: Growing up apart, coming together. Cambridge, MA: Belknap Press.

Maccoby, E. E., & Jacklin, C. N. (1987). Gender segregation in childhood. In E. H. Reese (Ed.), Advances in child development and behavior (Vol. 20, pp. 239-287). New York: Academic Press.

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Turner, P. J., & Gervai, J. (1995). A multidimensional study of gender typing in preschool children and their parents: Personality, attitudes, preferences, behavior, and cultural differences. Developmental Psychology, 31, 759-772.

Whiting, B. B., & Edwards, C. P. (1988). Children of different worlds: The formation of social behavior. Cambridge, MA: Harvard University Press.

About the Author
David Geary Ph.D.

David C. Geary, Ph.D., is a Curators’ Distinguished Professor in the Department of Psychological Sciences and the Interdisciplinary Neuroscience Program at the University of Missouri.

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