The target article represents a major theoretical contribution on several fronts. First, it highlights evolutionary functional accounts as indispensable for any comprehensive theory of attachment (as initially envisioned by Bowlby [Reference Bowlby1969/1982], but neglected by many subsequent attachment theorists). Second, it focuses on sex differences in adaptive problems and the resultant attachment-related strategic solutions as males and females enter the arena of mate competition. And third, it provides an elegant theoretical integration of the evolutionary psychological work on sex differences in mating strategies with important dimensions of individual differences – something urgently needed, but relatively neglected by much previous work in evolutionary psychology (Buss & Greiling Reference Buss and Greiling1999). In this commentary, we build upon these important advances, and propose some directions for exploring additional attachment differences across time, sex, and adaptive problem domain.
Evolution by selection tends to produce domain-specific and context-specific adaptations. It is theoretically problematic to assume that the attachment strategy as an adaptive response to environmental cues at one point during development will be adaptive if implemented in interactions in relationships later in life. To the degree that mother–infant attachment bonds serve functions that differ from those of friendship bonds and mateship bonds, and to the degree that they differ by sex, we expect selection to favor specificity of strategic solutions by relationship type, sex, and life phase.
It is reasonable to hypothesize that the sex differences in relative frequencies of insecure attachment styles that emerge at middle childhood are a result of sex differences in adaptive problems faced recurrently over deep evolutionary time during this stage of development. Del Giudice provides a compelling functional account for the shift in males towards an avoidant attachment style, but notes that the function of the female skew towards an ambivalent attachment style at this age is “less clear” (sect. 7.1.2, para. 2). If we focus on the finding that girls of parents who provide only inconsistent and unpredictable investment are the ones who tend to develop ambivalent attachment styles, we can conceptualize their ambivalent attachment psychology during middle childhood as a solution to the adaptive problems predicted by their parent-specific and kin-specific input.
The ambivalent attachment style is characterized by extreme dependence, emotional instability, and a desire to exert influence over the caregiver (sect. 2.2). These strategies, perhaps effective in eliciting as much investment as possible from parents, are unlikely to succeed in establishing strong alloparental bonds if directed toward same-sex peers during middle childhood. There is evidence that female–female friendships during childhood are shorter and more fragile than male–male friendships (Benenson & Christakos Reference Benenson and Christakos2003). If female friendships at this age lack the stability to endure until reproductive age, it strains credulity that they function as precursors to lasting alloparental bonds. Exhibiting high dependence and emotional instability toward female friends could easily backfire, as mechanisms that caused individuals to invest in non-kin who deplete resources, but who are unable or unlikely to reciprocate, would be selected against (Trivers Reference Trivers1971). From this perspective, we would not predict that attitudes and characteristics associated with ambivalent attachment at middle childhood would result in behavior that successfully initiates or maintains same-sex peer relationships.
If we instead hypothesize that this strategy is designed to be directed towards parents or kin, a functional hypothesis presents itself. In an environment in which male parental investment is inconsistent or nonexistent, such as that associated with ambivalent attachment, females who waited longer to reproduce, or who attempted to obtain all the necessary investment from their future mate, would have been out-competed by females who began reproducing early and who attempted to extract resources and investment from kin (Belsky Reference Belsky1997a; Reference Belsky, Cassidy and Shaver1999; Hoier Reference Hoier2003; Quinlan Reference Quinlan2003). Moreover, the earlier a female reproduces, the more likely she is to receive grandparental assistance and resources. Given cues to low or unstable male parental investment, one adaptive solution would be to reproduce early and maintain high levels of dependence upon close kin.
Because kin are usually already invested in the survival and reproductive success of their genetic relatives, we hypothesize that the care-eliciting strategies associated with ambivalent attachment directed specifically toward kin have the best chance of successfully extracting investment for a female's offspring. In contrast, similar strategies directed toward peers may result in alienation. In an environment in which male parental investment is unreliable or unlikely to be forthcoming, reproducing early capitalizes on as much grandparental investment as possible while these extended kin are still alive and can invest. Whereas securely attached individuals expect consistent support from family members, insecurely attached females may do best to focus on obtaining as much support as possible during middle childhood, because they cannot rely on it for the future.
Building on the theoretical advances proposed by Del Giudice, we have focused on functional explanations for the female switch to ambivalent attachment patterns during middle childhood. We suggest that this domain-specific approach will yield a psychological harvest for each sex, life stage, and relationship type. To the degree that sex-specific adaptive problems are associated with different types of dyads such as mateships, friendships, and kinships, we expect that selection will favor sex-specific, relationship-specific, and life-stage-specific strategic solutions.
