Evolutionary approaches to human behavior, such as Del Giudice's target article, have been accused of overemphasizing: (1) a limited (and often unsavory) set of topics, especially sex and mating; (2) selfishness; and (3) gender differences (see also Kenrick et al. Reference Kenrick, Ackerman, Ledlow and DeLamater2003). Each of these accusations is superficially true but is misguided at a deeper level. The approach presented in the target article helps emphasize this latter point.

1. Sex

An evolutionary approach is fundamentally concerned with reproduction, but reproduction involves more than just sex. Life history theory presumes that all organisms are designed to allocate resources over the lifespan in a way that maximizes reproductive success. Mating effort is certainly a central phase of any organism's life history. For salmon and century plants, which reproduce in a single burst and then die, the effort ends there. But for many organisms, including all mammals, the effort expended in attracting a mate and copulating is relatively minor compared to the effort devoted to parenting. In the case of humans, decades of parenting effort may precede decades of grandparental effort. From this perspective, reproductive strategy incorporates not only parent–child and parent–parent bonding, but also many other non-obvious aspects of life, including religious attendance and political affiliation (e.g., Weeden et al. Reference Weeden, Cohen and Kenrick2008). As suggested by Del Giudice, interpersonal attachment patterns may also reflect general reproductive strategies, and trade-offs between mating and parenting effort.

2. Selfishness

Selfish genes do not necessarily produce selfish organisms. Although genes tend to promote their own relative replication rates (Dawkins Reference Dawkins2006; Williams Reference Williams1966), those genes often construct organisms that make trade-offs favoring cooperation and kindness over narrow selfish behaviors. At the simplest level, people are often kind and generous to kin and to those with whom they expect to have future interaction (e.g., Ackerman et al. Reference Ackerman, Kenrick and Schaller2007; Burnstein et al. Reference Burnstein, Crandall and Kitayama1994). Economists and game theorists have been surprised at people's willingness to cooperate with others even when payoffs favor competition, but given the diffusion of genetic returns generated by common human social arrangements, people's generosity seems less irrational (Kenrick et al. Reference Kenrick, Sundie, Kurzban, Crawford and Krebs2008). For instance, a view of organisms as selfish might suggest that in a domain such as romantic relationship formation, which is so closely linked to genetic payoffs, competitiveness will rule the day. Yet, people cooperate in order to improve a range of reproductive goals (e.g., Ackerman & Kenrick, under review). Perhaps even more economically puzzling is the fact that people regularly turn down offers of resources from others, even when they are actually in need of help. Viewed within the framework of life history theory, such self-denial is often self-serving at a more ultimate level (Ackerman & Kenrick Reference Ackerman and Kenrick2008). Indeed, “irrational” behaviors, such as cooperative courtship and refusing offered aid, may be consequences of the very same trade-offs that produce secure and insecure attachment patterns.

3. Gender differences

Gender differences reflect critically important trade-offs, but so do gender similarities. Life history theorists have noted that reproductive strategies often diverge within a species, many times along gender lines. The underlying cause of such variation – differences in minimal obligatory parental investment – can result in a wide range of sex differences, from mate preferences (for willingness to engage in short-term relationships; Li & Kenrick Reference Li and Kenrick2006) to benevolence (between friends; Ackerman et al. Reference Ackerman, Kenrick and Schaller2007) to attachment patterns (in insecure attachment; Del Giudice, target article). For instance, in research on cooperative courtship, we find evidence that parental investment differences may motivate women to prefer assistance in building thresholds for potential mates, but motivate men to prefer assistance in overcoming these thresholds (Ackerman & Kenrick, under review). At the same time, gender similarities reveal equally important trade-offs. In biparental species (e.g., humans), many of the problems of parenting and mating are the same for males and females, and solutions to these problems play out through sex similarities in some of the same arenas that also exhibit sex differences – mate preferences (for partner qualities within short-term relationships; Li & Kenrick Reference Li and Kenrick2006), benevolence (between kin; Ackerman et al. Reference Ackerman, Kenrick and Schaller2007), and attachment patterns (in secure attachment; Del Giudice, target article). Indeed, in our studies of cooperative courtship, we find substantial similarities between men's and women's desires to cooperate, despite sex differences in how this cooperation materializes (Ackerman & Kenrick, under review).