Evolutionary Developmental Explanations of Gender Differences in Interpersonal Conflict: A Response to Trnka (2013)

Abstract

In focusing on gender differences in anger expression, Trnka (2013) provides a useful complement to the article by Ingram et al., (2012) analyzing gender differences in children's narratives about peer conflict. I agree that gender differences in anger are more likely to be the result of differential socialization processes regarding the expression of anger than by innate differences in the experience of anger. Gender differences in intersexual anger and aggression are likely to be affected by the social context, and especially whether a female is interacting with a romantic partner or an unknown male. The implication of socialization in anger expression raises the possibility that culture plays a causal role in encouraging cooperative breeding by inhibiting inter-female aggressive displays. Another of Trnka's proposals, that the expression of anger contributes to reconciliation and inhibits long-term relationship damage, is intuitively plausible and supported by the research literature, but not by data from the current study.

The thought-provoking commentary by Trnka (2013) provides a useful complement to my article with Campos, Hondrou, Vasalou, Martinho, and Joinson (2012) on gender differences in children's accounts of interpersonal conflict. I am grateful for the chance to further explore a finding which we did not discuss in detail in the original article, namely that girls and boys did not differ in the extent to which they described feeling anger in response to conflict. While the modest sample size of 132 children should lead us to be wary of a Type II error, it is certainly possible, as Trnka argued, that the original hypothesis that boys would more often report feeling anger than girls was misconceived, due to a reliance on older literature and a failure to distinguish between feeling and expressing anger. Trnka's review of the literature in this area is a valuable resource for researchers studying gender differences in anger, and provides convincing evidence that it is the expression rather than the experience of anger that differs most between sexes.

Trnka (2013) also provided several interesting evolutionary hypotheses for why this difference might exist. Three of his hypotheses make use of Harris's (1994) finding that women are more likely to approve of aggression by women against men than against other women. While I am not dismissing these hypotheses, I would like to comment that this finding related to a scenario involving potential romantic partners (on a date). Outside of that context, men were more approving of aggression against other (unknown) men. I am thus not convinced by Trnka's arguments that women might be more likely to make angry displays against men either because they think men will be more resilient to such displays (Hypothesis 4) or because they might face greater social sanctions for aggressing against other women (Hypothesis 1). Instead, a specific elevation of aggression by women towards male romantic partners can be accounted for by parental investment theory, since the man's investment in his partner's reproductive effort should make it maladaptive for him to respond to her anger with overwhelming levels of physical aggression. This idea is not incompatible with a modified version of Trnka's third hypothesis—which noted that women feel intense stress in response to male anger displays—since an angry display by a male romantic partner might serve as a signal that he did not, in fact, have a sense of shared parental investment with her.

More intriguing is Trnka's (2013) second hypothesis, that women are more sensitive to negative social feedback (often aimed at inducing negative social emotions, especially shame and guilt) than men are. As he pointed out, strong expressions of anger tend to be repressed by most cultures in most social situations (Trnka and Stuchlikova, 2013). This complements my own recent suggestion that negative social feedback against direct physical aggression contributes to the development of increasingly indirect aggressive strategies as children grow older (Ingram, in press). Females' greater susceptibility to negative social feedback would thus explain why they tend to use indirect aggression more than direct aggression (Hess and Hagen, 2006; but note that most reviews—e.g., Archer, 2004—are inconclusive as to whether girls engage in indirect aggression more than boys do). The greater inhibition of anger expression by females may be because human females are cooperative breeders (Hrdy, 2009)—unlike in, say, hyenas, where physical struggles for dominance tend to take place mainly between males (Wrangham and Peterson, 1996). The implication of negative social feedback in this process suggests a role for socialization processes—and therefore culture—in the evolution of behaviors, such as the inhibition of aggression, that help to support female cooperative breeding. More comparative, developmental, and cross-cultural work needs to be done to evaluate this proposal.

Finally, Trnka (2013) suggests that anger displays can sometimes function prosocially, as an aid to reconciliation between friends. This idea receives support from the finding of Recchia and Howe (2010) that siblings are more likely to compromise if they consider the other sibling's anger (in a conflict narrative) as well as their own. There were no data presented on compromise in the Ingram et al. (2012) study, but I reanalyzed the data on reconciliation to see if there was a link with descriptions of mutual anger in the conflict narratives. No significant effects were found using either a simple chi-squared test or generalized estimating equations (i.e., using the same statistical analyses as described by Ingram et al., 2012). However, this ad hoc result does not mean that a properly controlled and powered study might not find a link between anger displays and reconciliation, mediated by the conflict partners' greater awareness of each other's anger.