>Parental investment theory and the rigors of intersexual competition leads to the prediction that males will generally pursue relatively high-risk strategies compared to females and will thus be higher in behaviors typical of behavioral approach systems (BAS; dominance/sensation seeking, risk taking, impulsivity, exhibitionism) and lower on behavioral inhibition systems (BIS; fear, wariness, caution, safety seeking). Based on this predictions ethologists and evolutionary psychologists are interested in studying early gender differentiation in patterns of approach and avoidance behavior.
Developmental research in humans has produced a wealth of evidence that is generally consistent with predictions derived from parental investment theory. Research relevant to the BAS has consistently demonstrated that compared with girls, boys are more physically active from an early age (Eaton & Yu, 1989; Marcus, Maccoby, Jacklin, & Doehring, 1985; Money & Erhardt, 1972; Parke & Slaby, 1983), more assertive (Parke & Slaby, 1983), more aggressive, competitive, and dominant with peers (LaFreniere & Charleswood, 1983; LaFreniere, Dumas, Dubeau, & Capuano, 1992; Maccoby & Jacklin, 1974, 1980; Strayer & Strayer, 1976), and more oppositional with adults (LaFreniere et al., 1992). Boys are also more likely to take physical risks (Cristophersen, 1989; Ginsburg & Miller, 1982), engage in more rough-and-tumble play (DiPietro, 1981; Humphreys & Smith, 1987), and more high-energy socio-dramatic play involving guns and superheroes (Paley, 1984).
In contrast, research on the BIS has shown that preschool girls are more compliant to parents and teachers and rated by them as more socially competent (Cowan & Avants, 1988; LaFreniere et al., 1992, Maccoby, 1988). Girls rate themselves as more fearful, timid, nurturant, and empathic than boys (Fabes, Eisenberg, & Miller, 1990; Maccoby, 1988), and girls tend to show more interest and are more responsive towards infants than are boys (Blakemore, Berenbaum, & Liben, 2008). Parental ratings indicate that when sex differences are found in fearfulness and timidity, parents rate girls as more fearful than boys (Buss & Plomin, 1975; Maccoby & Jacklin, 1974), and they are more cautious in situations involving risks as noted above. All data derived from indirect sources must be interpreted cautiously and wherever possible validated against direct observation since the gender biases of the raters (parents, teachers, or child) cannot be ruled out. For excample, observational data do not show systematic sex differences in empathy and prosocial behavior, and in some situations boys or men are more likely to offer assistence than girls or women, particularly in situations involving significant risk (Eagly & Crowley, 1986; Fabes, Eisenberg, & Miller, 1990).<
Adaptive Origins - Evolution and Human Development
Peter LaFreniere; 2010