Life History Theory


Validated psychometric assessments of Mating Effort, Parenting Effort, and harshness/unpredictability of developmental environments


Manson, J.H., & Kruger, D.J. (2022). Network analysis of psychometric life history indicators. Evolution and Human Behavior, 43, 197-211.

Two of the controversies besetting the field of life history theory in psychology (LHT-P) are (1) whether life history strategy (LHS) is most fruitfully conceptualized as a latent reflective factor, or as a formative, descriptive construct and (2) whether the instruments most commonly used to measure psychometric LHS adequately cover its components. Psychological network analysis, as an alternative to latent factor modeling, affords an opportunity to map the relationships among narrower constructs hypothesized to comprise psychometric LHS. We recruited 1064 U.S. undergraduates, who completed instruments comprising 23 network nodes, including the K-SF-42 scales, Kruger’s (2017) mating effort and parental effort scales, and measures of childhood environmental harshness, current stability of resource access, sociosexuality, future orientation, and the dark triad. We tested pre-registered hypotheses pertaining to node centrality and node clustering (communities), and found mixed support for our predictions. Observed values of node predictability suggested that these 23 indicators comprise a self-determined network. The mating effort and parental effort scales were among the most central nodes, along with developmental SES, current resource stability, Machiavellianism and psychopathy. Contrary to prediction, most of the K-SF-42 subscales clustered into a single community of nodes. Our results add to recent literature casting doubt on the usefulness of widely used psychometric LH instruments. We expect that future research will reveal considerable heterogeneity in the sources of associations between the variables that have been characterized LHS indicators.


Kruger, D.J. (2022). Phenotypic mimicry distinguishes cues of mating competition from paternal investment in men’s conspicuous consumption. Personality and Social Psychology Bulletin, 48, 396-411.

Evolutionary psychologists propose that men’s conspicuous consumption facilitates mate attraction because it predicts resource investment in offspring. This article elaborates on the ultimate functions of men’s luxury displays based on Life History Theory. Three studies provide evidence for phenotypic mimicry, in which consumer product features mimicking male secondary sex characteristics indicate investment in mating competition, at the expense of paternal investment. Men owning shirts with larger luxury brand logos were rated higher on mating effort, lower on parental investment, higher on interest in brief sexual affairs, lower on interest in long-term committed romantic relationships, higher in attractiveness to women for brief sexual affairs, lower in attractiveness to women for long-term committed relationships, and higher in developmental environment unpredictability compared with men owning shirts displaying a smaller logo. Participants recognized the strategic use of luxury display properties across social contexts but did not consistently associate product properties with owners’ physiological characteristics.


Kruger, D.J., Kruger, J.S., Jordan, T., Sheu, J-J., Glassman, T., & Miller, S.A. (2020). Life history speed mediates the relationship between environmental conditions, health-related behaviors, and self-reported health. EvoS: The Journal of the Evolutionary Studies Consortium, 11, 68-93.

Life history theory (LHT) is a powerful explanatory framework in evolutionary science, integrating evolutionary, ecological, and socio-developmental perspectives. This study tests a life history framework for understanding variation in health-related behaviors in a modern society. Several life history indicators, including the Mini-K, Consideration for Future Consequences, and environmental Resource Stability were tested as mediations of the influences of neighborhood conditions, both developmental and current, on tendencies for health promoting and health adverse behaviors. Both Consideration for Future Consequences and Resource Stability mediated the relationship between neighborhood conditions and self-reported health and patterns of health behaviors. However, scores on the Mini-K did not mediate these relationships. The results of the current study suggest that progress in understanding and improving human health may be accelerated greatly by integrating insights from life history theory. Many human health challenges are related to trade- offs between immediate and long-term rewards. Interventions to promote healthy behavioral patterns will benefit from efforts to improve direct environmental affordances as well as long-term environmental stability.


Kruger, D.J., Fernandes, H.B.F., Cupal, S., & Homish, G.G. (2019). Life history variation and the preparedness paradox. Evolutionary Behavioral Sciences, 13, 242-253.

Life History Theory (LHT) is a powerful explanatory framework illustrating how ancestral and developmental environments shape allocations of effort to fitness-promoting domains in nested sets of trade-offs. LHT has previously informed basic research on evolved human psychology and behavior, it also has great potential for application to practical challenges and social concerns. LHT may help explain why there is typically a modest or null relationship between concern for environmental emergencies and the extent of preparation for needs during such an emergency. Experiences of more chaotic and hostile environments are associated with relatively faster life histories, and thus people with faster life histories may have a greater fear of environmental disasters and emergencies. However, those with relatively slower life histories would actually be more prepared for the contingencies of these emergencies because they exhibit greater future orientation and a higher degree of planning. Data from a demographically and geographically representative health survey in the Midwestern USA provided support for this hypothesis. Two indicators of environmental stability, a central influence on life history variation, predicted lower concern for emergencies but higher preparation for emergencies. Analyses accounted for socio-demographic characteristics associated with life history variation. General tendencies for future planning partially mediated some of these relationships.


Kruger, D.J., & Kruger, J.S. (2018). What do economically costly signals signal?: A life history framework for interpreting conspicuous consumption. Evolutionary Psychological Science, 4, 420–427.

Compared to women, men have a greater tendency to make conspicuous wealth displays and typically make greater contributions in non-somatic provisioning. Male resource displays often predict future paternal resource investments, however some conspicuous displays may function as mating effort at the cost of investment potential. Men who tend to make such displays may have less interest in long-term relationship investment and commitment and greater interest in short-term sexual relationships. Undergraduates read descriptions of two men purchasing automobiles with the same budget. One man purchased a new car for the sake of reliability (frugal investment), the other purchased a used car and allocated the remaining funds to conspicuous display features (new paint, larger wheels, louder sound system). Participants rated each character on life history characteristics, relationship interests, and relationship attractiveness. Participants rated the man who invested in flashy display higher on mating effort, lower on parental investment, higher on interest in brief sexual affairs, lower on interest in long-term committed romantic relationships, higher in attractiveness to women for brief sexual affairs, and lower in attractiveness to women for long-term committed romantic relationships, compared to the man with a frugal investment strategy. Participants demonstrated an intuitive understanding that some male conspicuous displays can indicate faster life history strategies. Human male luxury displays associated with high mating effort life histories may mimic the properties of male secondary sexual characteristics across species, and these displays may be more prevalent in environments fostering faster life histories.


Kruger, D.J., Köster, M., Nedelec, J.L., & Murphy, S.F. (2018). A life history framework advances the understanding of intentions for police cooperation. Evolutionary Behavioral Sciences, 12, 87-98.

Recent policing incidents have increased attention to relationships between community members and police. Academic research on attitudes toward police predominantly follows Tyler’s process-based model of policing; examining the influence of sociodemographic factors on perceptions of procedural justice, whether or not police are fair and trustworthy in their interaction with community members. We developed additional domains of attitudes toward police using evolutionary life history theory (LHT) as a basis for understanding relations with authority figures. We focus on the social roles of police officers in their communities: maintenance of the stability of society, the benefits in social status derived from the role of police officer, and the use of institutional power to exploit community residents and gain resources illicitly. Our new domains demonstrated explanatory power beyond perceptions of procedural justice, demographic factors, and a general life history speed indicator, in both undergraduate (N = 581) and Internet- recruited German (N = 471) samples.


Kruger, D.J. (2018). Facultative adjustments in future planning tendencies: Insights on life history plasticity from the Flint Water Crisis. Evolutionary Psychological Science, 4, 372–383.

Life History Theory (LHT) is a powerful explanatory framework examining how developmental environments and life experiences shape allocations of effort to fitness-promoting domains in nested sets of trade-offs. Time orientation is a central psychological aspect of human life history variation, representing the degree to which behaviors are oriented toward immediate versus future goals. Identifying critical sensitive periods for shaping life history variation and verifying the scope of life history plasticity are important issues for both theory and practical application. Many LHT frameworks propose sensitive periods from gestational development through middle childhood, though recent research suggests facultative adjustments may occur much later in the lifespan. The current study examines how experiences of poor tap water quality during the Flint Water Crisis, associated with toxic contamination and adverse health effects, may have affected time orientations. Degraded expectations for health and longevity may have affected psychological aspects of life history variation, with important consequences for health-related behaviors. Controlling for socio-demographics and other environmental factors associated with life history variation, those who experienced worse tap water quality had lower general tendencies for future planning. Tap water quality experiences predicted several health-related behaviors, independent of socio-demographics, some relationships were mediated through tendencies for future planning.


Kruger, D.J. (2017). Brief self-report scales assessing life history dimensions of mating and parenting effort. Evolutionary Psychology, 17, 1-9.

Life history theory (LHT) is a powerful evolutionary framework for understanding physiological, psychological, and behavioral variation both between and within species. Researchers and theorists are increasingly integrating LHT into evolutionary psychology, as it provides a strong foundation for research across many topical areas. Human life history variation has been represented in psychological and behavioral research in several ways, including indicators of conditions in the developmental environment, indicators of conditions in the current environment, and indicators of maturation and life milestones (e.g., menarche, initial sexual activity, first pregnancy), and in self-report survey scale measures. Survey scale measures have included constructs such as time perspective and future discounting, although the most widely used index is a constellation of indicators assessing the K-factor, thought to index general life history speed (from fast to slow). The current project examined the utility of two brief self-report survey measures assessing the life history dimensions of mating effort and parenting effort with a large undergraduate sample in the United States. Consistent with the theory, items reflected two inversely related dimensions. In regressions including the K-factor, the Mating Effort Scale proved to be a powerful predictor of other constructs and indicators related to life history variation. The Parenting Effort Scale had less predictive power overall, although it explained unique variance across several constructs and was the only unique predictor of the number of long-term (serious and committed) relationships. These scales may be valuable additions to self-report survey research projects examining life history variation.


Kruger, D.J., & Kruger, J.S. (2016). Psychometric assessment of human life history predicts health related behaviors. Psychological Topics, 25, 19-28. Invited, peer-reviewed article for special issue, Health Psychology: Current research and trends.

Life History Theory is a powerful framework that can help promote understanding of variation in health-related behavioral patterns and why they vary consistent with environmental conditions. An organism's life history reflects tradeoffs made in the allocation of effort towards specific aspects of survival and reproduction across the lifespan. This study examines the relationship between psychological indicators of life history strategy and health related behaviors in a demographically representative sample in the Midwestern USA. Slower life histories predicted higher levels of health promoting behaviors and lower levels of health adverse behaviors, even when controlling for relevant socio-demographic factors. The analyses provide a strong test of the hypothesized relationship between life history and health behavior indicators, as life history variation co-varies with these socio-demographic factors. Traditional public health efforts may be reaching their limits of effectiveness in encouraging health-promoting behaviors. Integrating an evolutionary framework may revitalize behavioral health promotion efforts.


Kruger, D.J., Nedelec, J.L., Reischl, T.M., & Zimmerman, M.A. (2015). Life history predicts perceptions of procedural justice and crime reporting intentions. Evolutionary Psychological Science, 1, 183-194.

Evolutionary life history theory (LHT) is a powerful organizing framework central to the life sciences. Interest in biosocial criminology is growing, and adoption of LHT may accelerate progress toward an integrative evolutionarily informed human science. We examined the relationship of life history to attitudes toward the police using data from a demographically representative community-wide survey in a Midwestern county with an urban center exhibiting high rates of violent crimes. As expected, life history was associated with demographic characteristics. Controlling for demographics, slower life history was associated with greater perceptions of procedural justice and police legitimacy, i.e., intentions to contact the police. LHT may promote an integrative human science and a deep theoretical framework for understanding modern social patterns.


Kruger, D.J., Fisher, M.L., De Backer, C., Kardum, I., Tetaz, M., & Tifferet, S. (2015). Human life history dimensions in reproductive strategies are intuitive across cultures. Human Ethology Bulletin, 30, 109-120.

Psychological research has been criticized for its extensive use of American university students to make broad claims about human psychology and behavior. Critics recommend a broader base of participants because there is substantial variability in experimental results across populations, and North American and Western European psychology pool participants may be outliers in comparison with the rest of the species. This challenge is especially pertinent for claims of species- universal evolved psychological architecture. One such claim has been made regarding recognition of human life history strategies. For example, previous research demonstrates that North American women and men can identify male and female characters with fast (high mating effort, low parental investment) and slow (low mating effort, high parental investment) life history strategies, make accurate predictions about their behavioral tendencies, and respond to them in ways that would facilitate participants' own reproductive success. The current project validates the understanding of fundamental life history dimensions across a wide range of cultures, therefore supporting the idea that there is a universality in human's ability to use, and perceive others' use of, life history strategies. Results for each language sample replicated patterns from North American participants. Ratings for characters clustered into two dimensions, mating effort and parental investment. Items most central to the theoretical constructs had the highest factor loadings.


Kruger, D.J., Aiyer, S.M., Caldwell, C.H., & Zimmerman, M.A. (2013). Local scarcity of adult men predicts youth assault rates. Journal of Community Psychology, 42, 119-125.

Father involvement reduces risky youth behavior at the individual level. We examine the association between the scarcity of adult men and youth violence at the Census Tract level across a small Midwestern city experiencing decades of economic adversity and high rates of violence. We calculated the ratio of men to women aged 25-64 and indicators of concentrated disadvantage across residential Census Tracts with 2000 US Decennial Census data and the average monthly assault rates for those aged 10-24 between June 2006 and December 2008 with data from the local police department. Adult male scarcity and the proportion of individuals 25 or older who had less than a high school degree were the two unique predictors of youth assault rates, together explaining 69% of the variance. Interventions promoting effective social, material, and protective support from fathers and other adult male role models may ameliorate risk for youth violence.


Kruger, D.J., Clark, J., & Vanas, S. (2013). Male scarcity is associated with higher prevalence of premature gestation and low birth weight births across the USA. American Journal of Human Biology, 25, 225-227.

Objectives: Modern adverse birth outcomes may partially result from mechanisms evolved to evaluate environmental conditions and regulate maternal investment trade-offs. Male scarcity in a population is associated with a cluster of characteristics related to higher mating effort and lower paternal investment. We predicted that modern populations with male scarcity would have shorter gestational times and lower birth weights on average.

Methods: We compared US Centers for Disease Control and Prevention county-aggregated year 2000 birth records with US Decennial Census data. We combined these data in a path model with the degree of male scarcity and known socio-economic predictors of birth outcomes as exogenous predictors of prematurity and low birth weight, with single mother households as a proportion of families with children as a mediator (N = 450).

Results: Male scarcity was directly associated with higher rates of low birth weight. Male scarcity made significant indirect predictions of rates of prematurity and low birth weight, as mediated by the proportion of families headed by single mothers. Aggregate socio-economic status also indirectly predicted birth outcomes, as mediated by the proportion of families headed by single mothers, whereas the proportion African American retained both direct and indirect predictions of adverse birth outcomes.

Conclusions: Male scarcity influences life history tradeoffs, with consequences for important social and public health issues such as adverse birth outcomes.


Kruger, D.J., & Vanas, S.B. (2012). Local scarcity of women predicts higher fertility among married couples and more single father households. Letters on Evolutionary Behavioral Science, 3, 17-20.

Influences of the sex ratio on the intensity of mating competition and selectivity for partners produce different outcomes in female biased and male biased populations because the reproductive strategies of men and women are somewhat divergent. Male scarcity enhances male mating opportunities and incentives for long-term commitment are diminished, encouraging serial and simultaneous polygyny. Paternal investment is lower in these populations, as indicated by higher divorce rates, more out-of-wedlock births, and a greater proportion of single mother households. Scarce females are more effective at securing commitment from partners and obtaining higher levels of resource investment. Women marry earlier in male biased populations. Although single father households are relatively uncommon, we expect to see higher proportions of households with children headed by single fathers where women are scarce. We also expect to see higher fertility among married couples, both because women may have greater bargaining power in reproductive decision-making and the role of woman in childbearing may be more salient and more highly valued. Data from the U.S. Census 2009 American Community Survey across 318 Metropolitan Statistical Areas supported these hypotheses.


Kruger, D. J., Munsell, M.A., & French-Turner, T. (2011). Using a life history framework to understand the relationship between neighborhood structural deterioration and adverse birth outcomes. Journal of Social, Evolutionary, and Cultural Psychology, 5, 260-274.

Life History Theory is a powerful framework for understanding how evolved functional adaptations to environmental conditions influence variation in significant life outcomes. Features indicating relatively high extrinsic mortality rates and unpredictability of future outcomes are associated with relatively faster life history strategies. Regulatory mechanisms that facilitated reproductive success in ancestral environments may contribute to adverse birth outcomes in modern technologically advanced populations. Adverse local environmental conditions may reduce maternal somatic investment in gestating offspring, consistent with long-term maternal interests. In this study, we demonstrated a relationship between neighborhood structural deterioration and adverse birth outcomes in Flint, Michigan, USA. We used Geographical Information Systems software to calculate the density of highly dilapidated structures, premature births, and low birth weight births in .25 mile square areas. Controlling for parental education and type of health coverage, the degree of structural deterioration was associated with the concentration of premature births and low birth weight births.


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. & Fisher, M. (2008). Women's life history attributes are associated with preferences in mating relationships. Evolutionary Psychology, 6, 245-258.

Life History Theory (LHT) is a powerful framework for examining relationship choices and other behavioral strategies which integrates evolutionary, ecological, and socio-developmental perspectives. We examine the relationship between psychological and behavioral indicators of women's life history attributes and hypothetical relationship choices with characters representing short-term and long-term male sexual strategies. We demonstrate that psychological indicators of women's life history strategies are related to predicted and actual behaviors in mating relationships. Women with insecure attachment styles, especially those with negative evaluations of both themselves and others (fearful attachment), were more likely to consider men with attributes indicating short-term mating strategies for short-term and long-term relationships than women with a secure attachment style. Women with relatively unrestricted sociosexuality were more likely to predict they would have sexual affairs with men in general, with the tendency being generally stronger when considering men with attributes indicating short-term mating strategies. Those who scored high on self-monitoring were also more likely to predict having sexual affairs and short-term relationships with these men. These and other findings demonstrate the usefulness of a life history approach for understanding women's relationship choices.


See also: Evolutionary Demography
See also: Mating strategies
See also: Evolution and Human Health