Recent Papers:

Kruger, D.J. (2008). Male financial consumption is associated with higher mating intentions and mating success. Evolutionary Psychology, 6, 603-612.

Cross-culturally, male economic power is directly related to reproductive success. Displays of wealth and social status are an important part of human male mating effort. The degree of male financial consumption may be related to variance in life history strategies, as differences in life history patterns are fundamentally differences in the allocation of effort and/or resources. Males who have higher mating intentions may maximize their economic displays, saving little and even spending beyond their capacity through the use of credit. These men may seek and possibly obtain a greater number of sexual partners. This hypothesis was tested in a randomly selected community sample of men aged 18-45 included in a telephone health interview. The degree of financial consumption was directly related to future mating intentions and past mating success, even when accounting for age, years of education completed, and marital status. The degree of financial consumption was not related to future mating intentions or past mating success for women in the same sample.


Kruger, D.J. (2008). Young adults attempt exchanges in reproductively relevant currencies. Evolutionary Psychology, 6, 204-212.

Adults in many species exhibit exchanges in reproductively relevant currencies, where males trade resources for sexual relations with females, and females have sex with males in exchange for provisioning. These exchanges can occur outside of a long-term partnership, which itself could be considered a commitment to the accessibility of reproductive currencies provided by each partner. The current study investigated whether young adults who are not in acute need of resources intentionally attempt reproductive currency exchanges outside of dating relationships or formal committed relationships such as marriage; and whether young adults have awareness of being the target of such attempts made by others. College students (N = 475) completed a brief survey assessing their own attempts to exchange reproductively relevant currencies, as well as others’ attempts to make these exchanges with them. Men were more likely to report making attempts to trade investment for sex and women were more likely to report attempted trades of sex for investment. Participants’ experiences of exchange attempts initiated by other individuals mirrored these patterns. Men were more likely to report another individual trying to trade sex for their investment, and women were more likely to report another individual trying to trade investment for sex with them. The vast majority of these attempted exchanges took place outside of existing relationships, although a small portion did lead to short or longterm relationships.


Kruger, D.J., Reischl, T.M., & Zimmerman, M.A. (2008). Time perspective as a mechanism for functional developmental adaptation. Journal of Social, Evolutionary, and Cultural Psychology, 2, 1-22.

Evolutionary Life History Theory (LHT) is a powerful framework that can be used for understanding behavioral strategies as functional adaptations to environmental conditions. Some evolutionary theorists have described how developmental environments can shape behavioral strategies. Theorists and previous research suggest that individuals developing in relatively less certain environments will exhibit riskier, present oriented, behavioral strategies because of the low probability of reproductive success for more cautious approaches. An evolutionary psychology approach to LHT includes the identification of psychological processes that regulate behavioral strategies as a result of developmental experiences. This paper proposes that time perspective is one psychological mechanism that may underlie functional developmental adaptation. A survey study of urban middle school students (N=607) assessed the relationship between perceptions of local social conditions, time perspective, and risky behaviors. Structural equation model analyses indicated that present and future orientations completely mediated the relationship of positive and negative aspects of students’ neighborhood social environment with reports of interpersonal aggression and illicit resource exploitation. This model had a better fit to the data than competing models depicting time perspective as a byproduct of either phenotypic strategy or social-environmental experiences.


Kruger, D.J. (2008). The importance of multi-level theoretical integration in biopsychosocial research. Psychological Topics, 16, 225-240.

There is a growing interest in the unification of health research in a biopsychosocial framework. However, increasing specialization and advancement in instrumentation makes it more difficult to bridge understanding across areas. It would be very useful to ground biopsychosocial research in the most powerful explanatory framework in the life sciences, evolution by natural and sexual selection. This would require and explanation of the functional significance of the phenomena related to the area of study, in addition to descriptions of the mechanism. The application of an integrative evolutionary framework will be illustrated with the example of sex differences in human mortality rates, which are related to endocrine, psychological, and socio-environmental factors. The integrative evolutionary model will be contrasted with a theoretical model that acknowledges physiological and social influences, but artificially separates them.


Kruger, D.J., Wang, X. T., & Wilke, A. (2007). Towards the development of an evolutionarily valid domain-specific risk-taking scale. Evolutionary Psychology, 5, 570-583.

From an evolutionary perspective, human risk-taking behaviors should be viewed in relation to evolutionarily recurrent survival and reproductive problems. In response to recent calls for domain-specific measures of risk-taking, we emphasize the need of evolutionarily valid domains. We report on two studies designed to validate a scale of risky behaviors in domains selected from research and theory in evolutionary psychology and biology, corresponding to reoccurring challenges in the ancestral environment. Behaviors were framed in situations which people would have some chance of encountering in modern times. We identify five domains of risk-taking: between-group competition, within-group competition, mating and resource allocation for mate attraction, environmental risks, and fertility risks.


Kruger, D.J.(2006). Male facial masculinity influences attributions of personality and reproductive strategy. Personal Relationships, 13, 451-463.

Facial masculinity may be used as a cue in female mate choice, as it reflects the success of the male genotype in its developmental environment. Women may maximize reproductive success by using a conditional strategy favoring highly masculine facial features for short-term relationships and feminized facial features in men for long-term relationships. Three studies examine reactions to masculinized and feminized male facial composites. Properties of the original composite image affect ratings of critical attributes and the magnitude of the differences in ratings between versions undergoing identical processes of geometric manipulation (Study 1). Both men and women attribute personality, behavior, and mating strategies consistent with predictions derived from the good genes and mating trade-off hypotheses (Study 2). Participants accurately grouped behavioral tendencies related to high mating effort/risky strategies and high parenting effort/risk adverse strategies and associated mating effort more so with masculinized faces and parenting effort more so with feminized faces (Study 3). These results indicate that male facial masculinity serves as a visual cue for inferring personality and reproductive strategy.