تجزیه و تحلیل طولی نظریه انتخاب جنسی از تفکیک جنسیتی و ادغام در اوایل نوجوانی

The three objectives in this longitudinal study were motivated by sexual selection theory. The theory specifies the role of sexually segregated groups and the effects of dominance in male groups and relational/indirect aggression in female groups for heterosexual relationships. Using a multi-method, multi-informant, longitudinal design we studied youngsters (N=138) across their first two years of middle school. First, we examined the nature of change in segregation and dating popularity across two years during early adolescence. Second, a model derived from sexual selection theory is tested to explain the ways in which boys and girls are nominated for hypothetical dates (dating popularity). Third, we examined the role of “poke and push courtship” behavior in boys’ and girls’ dating popularity. Results indicate that although groups did not become more integrated with time, changes in peer group sexual integration co-varied dynamically with dating popularity. Secondly, dominance-related strategies were more important for boys than girls in dating popularity whereas indirect, or relational, aggression strategies were more important for girls than boys. Third, “poke and push courtship” behaviors did not influence peer group integration or dating.

Sexual selection theory was proposed by Darwin (1871) in his discussions of differences in individuals’ breeding where success depends on two factors: (1) Competition within one sex for access to members of the opposite sex, and (2) choice by individuals of one sex for members of the opposite sex. In many mammals, including human and nonhuman primates, males typically compete with each other for access to females and females choose specific males. In this paper we draw from sexual selection theory, as originally proposed by Darwin (1871) and later refined by contemporary scholars (i.e., Clutton-Brock, 1983; Trivers, 1972 and Trivers, 1985) to extend the exhaustive review of sexual segregation, later integration, and sex differences in aggression proffered by Maccoby (1998). This level of theorizing provides testable hypotheses for the distal and proximal forces responsible for sexual segregation and sex differences in agonistic strategies. As Maccoby noted, socialization theories alone do not adequately address these issues. The theory predicts that mammalian males’ reproductive strategy is likely to be one of frequent mating and low investment in the reproductive effort, relative to females’ effort (Trivers, 1972). This results in heightened levels of male intra-sexual competition and sexual dimorphism (Pellegrini & Archer, in press; Plavcan & van Schaik, 1997). In many mammals, including humans, males segregate into same sex groups; for human this begins at around 3 years and peaks at 8–11 years (Maccoby, 1998), where males can exercise and engage in vigorous and rough behaviors (Pellegrini, 2002). The social roles that males take in these segregated groups are associated with their being the more physically active and competitive sex (Pellegrini, 2002; Pellegrini, Kato, Blatchford, & Baines, 2002). In segregated groups, males engage in vigorous competitive activities using physical aggression and dominance-related strategies to sort out their status. Segregated groups are the socialization contexts in which males learn and develop the skills necessary for status and maintain the physical conditioning associated with status. Status and physical conditioning are important for both intra-male competition and for making males more attractive to females (because these are indicators of both “good genes” and resource holding potential). Relatedly, an additional function of sexually segregated groups, for both boys and girls, may be that the out group (or opposite sex) remains “exotic” (Bem, 1996) enough to be sexually interesting. In contrast to males, females segregate into more sedentary and less physically aggressive groups (Maccoby, 1998). This strategy is also determined by differential investment in reproductive efforts (Trivers, 1972). Females’ high investment in child care aspects of reproduction results in their taking on social roles that are more nurturing and less risky so that they can provision and protect their offspring (Campbell, 1999). From this view, females tend to choose a dominant mate, or one who can provide resources and protection for their offspring. When females do use aggression to acquire resources they should use indirect, or relational, aggression as a part of their reproduction strategy because it is safer than more direct forms of aggression. Using relational aggression (for example, spreading rumors; Bjorkqvist, 1994; Crick & Grotpeter, 1995) does not involve direct confrontation between conspecifics. Such indirect strategies mean that females are more likely to “stay alive” (Campbell, 1999) and invest in the reproductive effort of raising offspring. More proximally, socialization pressures reinforce these differences. They begin very early at home when fathers engage in rough and vigorous play with their sons much more frequently than with their daughters (MacDonald & Parke, 1986; Parke & Suomi, 1981). Parents also differentially furnish boys’ and girls’ bedrooms with toys and props that further reinforce these differences (Rheingold & Cook, 1975). For example, boys’ rooms contain more paramilitary toys than girls’ rooms (e.g., GI Joe) while girls’ rooms have more dolls, tea sets, and doll houses. These differences continue in segregated peer groups as children as young as 3 years are reluctant to interact with opposite sex peers (Maccoby, 1998; Serbin, Connor, Burchardt, & Citron, 1979). Segregation manifests itself most commonly in children choosing to interact with same sex peers during their free time periods where there is little adult supervision (Blatchford, 1998; Thorne, 1986 and Thorne, 1993). This phenomenon is readily observable in preschool and primary school contexts where children are given free choice of social partners, such as during recess or at lunch time, and especially in the context of competitive games (Blatchford, Baines, & Pellegrini, in press; Pellegrini et al., 2002; Thorne, 1986 and Thorne, 1993). While segregated peer groups continue to exist into early adolescence, often in the form of “cliques” (Brown, Eicher, & Petrie, 1986; Dunphy, 1963), youngsters also begin to interact more with opposite sex peers at this time. The same biological and socialization forces that maintained sexual segregation during childhood conspire to bring the two sexes together with the onset of puberty and adolescence (Maccoby, 1998). Hormonal changes during adolescence as well as societal stress on heterosexual relationships (Collins & Sroufe, 1999; Furman, 1999) result in boys and girls showing increased interest in one another. This interest is realized by an increase in cross-sex contact as well as increased interest in dating (Dunphy, 1963; Pellegrini, 2001). Junior high and middle schools, which house early adolescents, afford prime opportunities for youngsters to interact with peers of the opposite sex (Blatchford, 1998; Pellegrini, 2002). Indeed, Maccoby (1998, p. 73) suggests that school is the “major setting” where children encounter peers of the other sex. Consequently, middle school is a very interesting and ecologically valid venue to study early adolescents’ emerging heterosexual relationships. Thus, to understand the beginnings of heterosexual relationships it is sensible to study youngsters as they first make the transition into middle school and follow them longitudinally. In this way the natural history of relationships with opposite sex peers can be studied from the point when youngsters first encounter each other in an institution designed for young adolescents. In this study we document the development of sexual integration and early dating popularity from the points of view of boys’ dominance relationships and of girls’ uses of indirect, or relational, aggression (e.g., Pellegrini & Archer, in press; Pellegrini & Bartini, 2001). The first objective of this study was to describe changes in segregation toward integration and dating popularity across the first two years of middle school. As part of this objective, we document the sexual composition of peer groups and the ways in which sexual segregation in peer groups and dating popularity influence each other dynamically across the first two years of middle school. The second objective was to test two models of dating popularity, one for boys and one for girls. The male model stresses the role of dominance and the female model stresses the role of indirect, or relational, aggression. Dominance, as a construct, is especially useful in explaining the ways in which boys and girls begin to interact with each other during early adolescence. Indeed, dominance must be understood in terms of the resources for which individuals are competing, not as an end on to itself. Males compete with each other in dominance-related interactions so as to gain access to some resource and the resulting dominance hierarchy indexes individuals’ relative access to those resources. In adolescence and with the onset of puberty, heterosexual relationships, in the form of dating, become a very important resource for both males and females (Collins & Sroufe, 1999). Thus, dominant males should have access to females and females should find these males attractive and nominate them for hypothetical dates (Bukowki, Sippola, & Newcomb, 2000; Pellegrini & Bartini, 2001). Dating for young adolescents is an extension of larger social groupings, rather than the intimate dyadic relationships characteristic of adulthood (Dunphy, 1963). Dating during this period usually consists of groups of youngsters going out together to public places (Connolly & Goldberg, 1999; Furman, 1999) and these groups are often the amalgam of male and female cliques (Furman, 1999). For these reasons we operationalized dating as a form of group popularity: being invited to a hypothetical party by a member of the opposite sex. Sexual selection theory leads to the following predictions. Segregation should decrease for both boys and girls across early adolescence (in the case of this study, across the first two years of middle school). Furthermore, sexual segregation and dating popularity should, for both sexes, influence each other such that decreases in segregation should covary with increases in dating popularity across time. Specifically, we document two forms of change. First, we document simple changes in the degree to which peer groups become sexually integrated (or less segregated). Secondly, we examine the dynamic changes in segregation (for males, the ratio of males to the total of males and females in an immediate group, and for females, the ratio of females to the total of males and females) as these changes covary with dating popularity (being invited to a hypothetical party by an opposite sex peer) across developmental time (four measurement points during the first two years of middle school). As sexual segregation decreases, dating should increase and vice versa. Second, we test hypothetical models of dating popularity for males and females. Our models stress the role of dominance for males and the role of indirect, or relational, aggression for females. During early adolescence, girls find dominant boys attractive (Bukowki et al., 2000; Pellegrini & Bartini, 2001). Dominant boys are, by definition, leaders of their peer groups. Consequently, girls often want to associate with high status boys. The importance of a high status “date” is consistent with the notion that early dating is a group-oriented phenomenon and by choosing to “go out” with high status boys, girls enhance their own status. Girls, however, are not as reliant on dominance-related strategies as boys. As noted already, girls tend to use indirect, or relational, aggression as a way in which to manipulate their female peers, and enhance their reputation in the wider peer group (Bjorkqvist, 1994; Campbell, 1999; Crick & Grotpeter, 1995). Relational aggression is where individuals enhance themselves by damaging reputations and social relations of rivals through the use of gossip, rumor, and threats. Because of the preponderance of this behavior in females, we expect it to be more important in predicting girls’ than boys’ dating popularity. Although there are socialization and biological pressures to initiate heterosexual relationships during adolescence, we must also recognize that cross-sex interaction is very difficult for youngsters of this age. Initial cross-sex contact is quite risky to initiate to the extent that it breaks well-established patterns of sex segregation entrenched since early childhood (Dunphy, 1963; Maccoby, 1998; Serbin et al., 1979). Furthermore, there is a real risk that overtures to opposite sex peers will be publicly rejected, resulting in public embarrassment for the initiator. One way in which youngsters can minimize these risks is to use overtures that are playful and ambiguous in their intent. Specifically, youngsters of this age sometimes resort to “poke and push” courtship behaviors such as, playfully hitting, pushing, grabbing, and teasing an opposite sex peer (Maccoby, 1998; Schofield, 1981). These behaviors can be interpreted as affiliative overtures by the recipient and reciprocated. Alternatively, they can be rejected. When the overture is reciprocated, cross-sex contact has been successfully initiated. When the overture is rejected the initiator saves face because the bout can be dismissed as playful and not serious. We predict that poke and push courtship will be equally important for males and females in predicting dating. In summary, we will examine the following hypotheses. First, peer groups should become less segregated (more integrated) with time (we also will examine the longitudinal trend of the other variables, but not offer specific hypotheses is this regard). In addition, segregation (integration) should covary with dating popularity across time. Second, for the male model of hypothetical dating, we predict that dominance and group segregation (integration) will predict dating popularity. For the female model, we predict that relational (indirect) aggression and segregation (integration) will predict dating popularity. In these analyses we consider “prediction” at the group and individual levels by using, respectively, generalized linear mixed models and 0-order correlation coefficients. Third, we predict that poke and push courtship will be equally important for males and females in predicting dating popularity.