We present a psychometric scale that assesses risk-taking in 10 evolutionary content domains: between-group competition, within-group competition, status-power, environmental exploration, food selection, food acquisition, parent-offspring conflict, kinship, mate attraction, and mate retention. We report on three studies that evaluate the scale’s validity and consistency for a sample of 1,326 participants who rated their likelihood of engagement in, the perceived riskiness of, and the benefit associated with various risky activities. Behaviors were framed as modern-day analogues of qualitatively similar actions in recurring problem domains of the ancestral environment that were potentially beneficial but also potentially costly to survival and reproductive success. As expected, respondents’ degree of risk-taking was not consistently risk-averse or risk-seeking across content domains, and a set of eight life-history variables had domain-specific effects on risk-taking propensity. In most domains, men were significantly more risk-seeking than women, but in 2 of the 10 domains—food selection and kinship risks—women were more risk-prone than men. Participants who reported not being married or in a committed relationship scored significantly higher in the domains of mate attraction and mate retention. Age, reproductive goal-setting, parental status, number of siblings, and birth order also affected the formation of risk thresholds.

Abstract:We generated an inventory of 27 interpersonal behaviors and examined the extent to which participants judged each behavior as cheating on a long-term partner. We predicted variation in these judgments based on participant sex and attachment insecurity. Ratings for items ranged considerably; participants rated sexual behaviors as most indicative of cheating, then erotic behaviors, followed by behaviors consistent with a romantic relationship, and then behaviors related to financial support. Women rated ten items higher than did men, and men's ratings were higher on a minor financial support item. Higher attachment anxiety was associated with higher ratings for 18 of 27 behaviors; higher attachment avoidance was associated with lower scores on five items and higher scores on one item. Principle Axis Factoring identified three dimensions; sexual interaction, behaviors indicating close relationships, and casual social interaction. We discuss these results using the framework of attachment theory and sex-specific mating strategies.

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When women are scarce in a population relative to men, they have greater bargaining power in romantic relationships and thus may be able to secure male commitment at earlier ages. Male motivation for long-term relationship commitment may also be higher, in conjunction with the motivation to secure a prospective partner before another male retains her. However, men may also need to acquire greater social status and resources to be considered marriageable. This could increase the variance in male marital age, as well as the average male marital age. We calculated the Operational Sex Ratio, and means, medians, and standard deviations in marital ages for women and men for the 50 largest Metropolitan Statistical Areas in the United States with 2000 U.S Census data. As predicted, where women are scarce they marry earlier on average. However, there was no significant relationship with mean male marital ages. The variance in male marital age increased with higher female scarcity, contrasting with a non-significant inverse trend for female marital age variation. These findings advance the understanding of the relationship between the OSR and marital patterns. We believe that these results are best accounted for by sex specific attributes of reproductive value and associated mate selection criteria, demonstrating the power of an evolutionary framework for understanding human relationships and demographic patterns.