Del Giudice is to be congratulated for such a bold expansion of attachment theory. The target article resumes the dialogue between evolutionary and developmental theories that proved to be such fertile ground for Bowlby himself. Sex differences in child attachment patterns and their possible preparation for adult mating strategies have been largely neglected within attachment theory, possibly in an attempt to distinguish it from its psychoanalytic origins. Accordingly, a new set of evolutionary hypotheses has emerged that will provide a welcome direction for theoretical integration and future research.
In this commentary, we focus on the integration of disorganized attachment into the life history model, arguing that it may represent a limit to the adaptive function of attachment, and we also aim to briefly draw out some of the clinical consequences of this view. Del Giudice has focused his theory around the organized patterns of attachment while, by his own admission, excluding disorganized attachment. Because the life history theory of attachment is particularly concerned with the reproductive implications of early environmental adversity, disorganization could be considered, especially given that its prevalence is around 15% in low-risk middle-class families (Van IJzendoorn et al. Reference Van IJzendoorn, Schuengel and Bakermans-Kranenburg1999). Furthermore, the prevalence rates tend to increase in proportion to the degree of developmental adversity – parental depression, adolescent parenthood, unresolved loss or trauma and marital discord – reaching a high of up to 80% among maltreating and drug-abusing parents (Green & Goldwyn Reference Green and Goldwyn2002; Lyons-Ruth & Jacobvitz Reference Lyons-Ruth, Jacobvitz, Cassidy and Shaver1999). Although in some cases a secondary organized attachment pattern can be discerned beyond the disorganized phenomena, at the extreme, cases of multiple attachment strategy in early childhood and unclassifiable adult attachment states of mind (coded as “Cannot Classify” [CC] on the Adult Attachment Interview), suggest a pervasive disorganization of the attachment system that has been found to be strongly associated with child and adult psychopathology (Bakermans-Kranenburg et al. Reference Bakermans-Kranenburg, van IJzendoorn and Juffer2005; Green & Goldwyn Reference Green and Goldwyn2002).
In introducing the formal classification of disoriented/disorganized attachment using the Strange Situation Procedure, Main and Solomon (Reference Main, Solomon, Greenberg, Cicchietti and Cummings1990) described its ethological and evolutionary framework as one of “fright without solution” (Hesse & Main Reference Hesse and Main2000). The behavioural indices of disorganized attachment closely resemble phylogenetically conserved mammalian fear responses: flight, attack, and freezing behavior (Main & Solomon Reference Main, Solomon, Greenberg, Cicchietti and Cummings1990). However, in this case, such responses are displayed toward the caregiver who ought to be a haven of safety. Thus, a degree of behavioural conflict occurs between a security-seeking attachment system and a fear-responding survival system. This is reflected in other common indices of disorganization such as simultaneous display of distress and avoidance, undirected or misdirected movements, and disrupted movements or gestures – all of which suggest the enactment of a conflict between approach and avoidance. Such an explanation draws heavily on Bowlby's original assumption that the adaptive function of attachment is largely to do with seeking protection and, therefore, attachment behaviors in infants function to regulate fear via proximity seeking.
Del Giudice cites several studies in which sex differences in the frequency and degree of severity of disorganization have been noted, with male infants tending to be the more frequently and severely disorganized. Males are more prone to aggressive pathology in middle childhood, as has been noted frequently in the conduct disorder literature. An organized response to parental insensitivity in the form of avoidant attachment may well produce an adaptive low-investment parenting strategy for males. However, the more severe modes of aggression associated with disorganization may well produce an antisocial behavioral pattern in males which, like many forms of severe psychopathology, would be maladaptive and reduce reproductive fitness.
Given disorganization's strong association with extremes of developmental adversity and dysregulation of stress responses in infancy and early childhood, why might it be more prevalent in males? Either males are more vulnerable to disorganization, or the primary caregivers of males – typically mothers – are more disorganizing in their caregiving toward male infants under some conditions. In addition to the investigation of proximate mechanisms, there may be an application of the Trivers-Willard hypothesis: namely, for polygynous species, parents in poor conditions are likely to invest more in females, who are more likely to bear them at least some grandchildren, whereas males raised in poor conditions will be unlikely to compete with other males and therefore would attract minimal investment (Trivers & Willard Reference Trivers and Willard1973). The evolutionary hypothesis that such fearful and frightening caregiving may be greater toward male offspring would be interesting to investigate.
Evolutionary concepts are increasingly considered in definitions of psychopathology as an impairment of a biologically meaningful function (Wakefield Reference Wakefield and Buss2005). The pathogenic effect of disorganization may be outside of the average expectable caregiving experiences for which humans are selected. In contrast, avoidant and preoccupied attachments are organized and strategic responses to parental – and most particularly maternal – caregiving, including sensitivity and attunement (see de Wolff & van IJzendoorn Reference De Wolff and van IJzendoorn1997). This distinction is an important one because the life history hypothesis serves to reinstate organized but insecure attachments as potentially adaptive in both the social and evolutionary senses, and in the latter, arguably serving to increase reproductive fitness in harsh rearing environments. This suggests that the attachment behavior system is both more robust and flexible than the normative assumptions of ideal security imply. However, beyond a certain threshold, highly adverse caregiving environments involving direct or implied dangers, consistent with maltreatment or caregiver absence (psychological or physical), lead to pathological outcomes and, although it remains to be established, reduced fitness.
Implications for future directions include extensions of the research agenda to psychobiological dysregulation arising from disorganization. Implications of disorganization for pubertal timing and reproductive strategy, mate choice, and degree of parental investment could be investigated. Finally, clarification of the classification of disordered attachment and enhanced clinical interventions can be derived from a better understanding of the biological function and dysfunction of the attachment system across the human life cycle.
