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.
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.
This chapter presents an evolutionary framework for understanding human health issues across the lifespan and variation in health related behaviors and outcomes. Life History Theory in particular provides great insight into health challenges and how health issues relate to the intersections of our evolved genetic heritage and the developmental and current environments we inhabit. This framework would provide a strong foundation to further advance human health conditions in modern societies.
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.
The field of Public Health is quite broad in scope, diverse in activity, and fragmented both theoretically and methodologically. Public Health research and practice continues to improve health outcomes and enhance both the duration and quality of life, yet the pace of this progress could be greatly accelerated by establishing a universal and deep framework for understanding and integrating disparate undertakings. Advances in medical and health promoting technologies will continue to extend the boundaries of saving lives in danger; however, Public Health efforts to promote healthy behaviors and discourage health adverse behaviors still struggle in their effectiveness. We may be reaching a limit in the degree of returns from traditional educational and motivational health-promoting practices. Evolutionary theory is the most powerful explanatory system in the life sciences and is the only framework that can unify knowledge in otherwise disparate fields of research. In recent decades, there have been considerable advances in the application of evolutionary biology to health issues, most often on physiological aspects. Yet behavioral health researchers using an evolutionary framework are very few in number and face constraining disciplinary factors. Those with backgrounds in evolutionary research would be surprised by the near absence of evolutionary content in presentations at public health conferences and journal articles. Health researchers and practitioners could benefit considerably from an understanding of the basic principles of evolution and how humans have been shaped by natural and sexual selection, even if they are not explicitly testing evolutionary hypotheses. Life History Theory in particular is a powerful framework that can help promote understanding of variation in behavioral patterns related to health and why they vary consistent with environmental conditions. This chapter will introduce this framework and illustrate its application to advance the understanding of health issues across the human lifespan.
Studies of patriarchy typically focus on women's subordination to men and the detrimental consequences for females. In this study, however, the authors predict that greater social empowerment of women will be associated with smaller mortality differences between women and men, which may seem counterintuitive from a nonevolutionary perspective. In other words, they predict that higher levels of societal patriarchy will be associated with greater levels of excess male mortality. They propose that the degree of patriarchy reflects both the extent of male control of females as reproductive assets, as well as the degree of male competition for positions of high status and power that have historically conferred disproportionate reproductive benefits. The intensity of this male competition directly predicts the extent to which male mortality rates exceed female mortality rates. The authors examined national level sociodemographic and mortality data from the WHO Mortality Database, United Nations, CIA World Factbook, and the Encyclopedia of World Cultures. They found that across nations, women's social and economic empowerment had a strong inverse relationship with the disparity between male and female mortality from both external (direct behavioral) and (behaviorally mediated) internal causes, even when accounting for general economic inequality and the prevalence of polygyny. This study demonstrates the usefulness of an evolutionary framework for explaining contemporary social phenomena and important public health issues.
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.
Evolutionary theory is the most powerful explanatory system in the life sciences and is the only framework that can unify knowledge in otherwise disparate fields of research. Considerable advances have been made in the application of evolutionary biology to health issues in recent decades. Health researchers and practitioners could benefit considerably from an understanding of the basic principles of evolution and how humans have been shaped by natural and sexual selection, even if they are not explicitly testing evolutionary hypotheses. Life History Theory is a powerful framework that can be used for examining modern human environments and developing environments that maximize opportunities for positive health outcomes. Many of the recommendations derived from this framework converge with the visions of current public health advocates. Despite the benefits of an evolutionary framework, the challenges that face those attempting to integrate evolutionary theory into public health are perhaps greater than those in the social sciences. Although considerable advancements in the understanding of health issues have already been made, health researchers with an evolutionary perspective are very few in number and face constraining disciplinary attributes. Advances in medical technology will continue to extend the boundaries of saving lives in danger, however traditional public health efforts may be reaching their limits of effectiveness in encouraging health-promoting behaviors. This may partially account for the current interest in broad social and policy change to enhance health and reduce health disparities amongst sub-populations. Such substantial physical and social restructuring will face many challenges and gradual progress may be enhanced by a strong foundation of evolutionary human science. The slow but eventual integration of evolutionary principles will gradually enhance the effectiveness of health interventions and provide an ultimate explanation for patterns in health outcomes that are otherwise puzzling. The speed at which the field of public health adopts a Darwinian framework has yet to be determined, and several futures are possible. This pace will depend on several factors, including the visible utility of evolutionary theory for addressing the health promotion goals of the field.
Sex differences in human mortality rates emerge from a complex interaction of genetic heritage and developmental environment. Although mortality is not in itself a behavior, it is an indirect product of behavior and physiology and thus responsive to life history variation in resource allocation, behavioral tendencies, and relevant environmental conditions. The explanatory framework of Tinbergen's Four Questions is sufficiently powerful in generalization to promote understanding of this phenomenon. Excess male mortality is a result of a trade-off between competitiveness and longevity. Male life history gives greater emphasis to reproductive effort at the expense of somatic effort, and mating effort at the expense of longevity compared to female life history. Men exhibit riskier behavioral patterns and greater physiological susceptibility, dying at higher rates from behavioral and most non-behavioral causes across the lifespan. The magnitude of the sex difference in mortality in developed nations peaks when males sexually mature and enter into mating competition. Social and environmental conditions intensifying male competition for resources, status, and mates lead to increased male mortality.
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.
Male behavior and physiology is designed for enhanced competitiveness at the expense of longevity, resulting in higher mortality rates compared to females in most species. These differences vary across populations consistent with factors indicating the intensity of male mating competition. Reproductive dynamics are strongly influenced by the relative proportions of potentially reproductive males and females in a population. Because the reproductive strategies of men and women are somewhat divergent, market influences on the intensity of mating competition and selectivity for partners produce different outcomes in female biased and male biased populations. The single-child law implemented in China in 1979 has led to increasing proportions of men in the Chinese population. Using historical mortality data, we found a trend for increasing sex differences in Chinese mortality rates from 1982 to 2000. This increase was most prevalent in young adulthood, when male mating competition is most intense as males reach sexual maturity and seek female partners. In contrast, males exhibited more survival gains than females in infancy and early childhood.
Sex differences in mortality rates stem from a complex set of genetic, physiological, psychological, and social causes whose influences and interconnections are best understood in an integrative evolutionary life history framework. Although there are multiple levels of mechanisms contributing to sex based disparities in mortality rates, the intensity of male mating competition in a population may have a crucial role in shaping the level of excess male mortality. The degree of variation and skew in male reproductive success may shape the intensity of male mating competition, leading to riskier behavioral and physiological strategies. This study examines three socio-demographic factors related to variation in human male reproductive success; polygyny, economic inequality, and the population ratio of reproductively viable men to women across nations with available data. The degrees of economic inequality and polygyny explained unique portions in the sex difference in mortality rates, these predictors accounted for 53% of the variance. The population ratio of reproductively viable men to women did not explain any additional variance. These results demonstrate the association between social conditions and health outcomes in modern nations, as well as the power of an evolutionary life history framework for understanding important social issues.
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.
Sex differences in mortality rates stem from multiple causes that are best understood when integrated in an evolutionary life history framework. This study investigates the relationship of sex differences in mortality rates across nations to indicators of the life history characteristics of populations. Controlling for gross national income per capita, the overall sex difference in mortality rates was directly related to the adolescent fertility rate, the percentage of newborns with low birth weight, and was inversely related to the average mother's age at birth of first child. Sex differences for behavioral (external) causes of mortality were also directly related to the difference between the average age of males and females at first marriage. These findings indicate that the sex difference in mortality rates is an important life history indicator, and is related to reproductive patterns. Greater sex differences in mortality may reflect greater degrees of male competition for resources, social status, and mates.
Sex differences in mortality rates stem from a complex set of genetic, physiological, psychological, and social causes whose interconnections are best understood in an integrative evolutionary framework. We predicted that the transition from centrally planned to market economies in Eastern Europe inflated the discrepancy between male and female mortality rates, because economic uncertainty and increasing variation and skew in social status and resources should increase risky male behavior and the impact of stress on physiological susceptibility to internal causes of death. We computed the ratio of the male mortality rate to the female mortality rate separately for 14 Eastern European countries and for the combined population of 12 Western European countries in the pre-transition (1985-1989), transition (1990-1994), and post-transition (1995-1999) periods. We found that the Male to Female Mortality Ratio (M:F MR) for 14 Eastern European nations increased during the years of economic transition, most prominently during early adulthood. Larger sex differences in mortality rates occurred in both young adulthood, reflecting a shift towards riskier behavioral strategies, and middle adulthood, indicating greater physiological susceptibility to stress. For 12 of the 14 Eastern European nations, the increase was substantially larger than the slight increase in the overall Western European M:F MR. The impact of the transition on the magnitude of mortality discrepancy across countries varies considerably and likely reflects conditions particular to each country. These findings illustrate how traits shaped by natural selection interact with environmental conditions to influence male psychology and ultimately mortality patterns.
Sex differences in mortality rates stem from genetic, physiological, behavioral, and social causes that are best understood when integrated in an evolutionary life history framework. This paper investigates the Male-to-Female Mortality Ratio (M:F MR)from external and internal causes and across contexts to illustrate how sex differences shaped by sexual selection interact with the environment to yield a pattern with some consistency, but also with expected variations due to socioeconomic and other factors.
Invited, peer reviewed article for the special issue on Evolutionary Psychology.
Being male is the strongest demographic predictor of early mortality in Croatia. For every woman who dies between the ages of 15 and 34, three men die. Between the ages of 15 and 54, men are four times as likely as women to die from behavioral causes of death, such as accidents, homicides, and suicides. A causal explanation for sex differences in mortality must be based on an understanding of how sex differences were shaped by natural selection, and how those differences interact with environmental factors to create observed patterns and variations. In brief, males have been selected for riskier behavioral and physiological strategies than women, because of the greater variance and skew in male reproductive success. This paper examines the sex difference in Croatian mortality in three parts. First, we quantify the Croatian Male to Female Mortality Ratio (M:F MR) for 9 major causes of death across age group to provide a richer understanding of the sex difference in mortality from a life history framework. Second, we compare the Croatian M:F MR from behavioral, internal, and all causes with that of the available world population to demonstrate how Croatian mortality can be understood as part of a universal pattern that is influenced by unique environmental context. Third, we investigate how the War of Independence in 1991-1995 affected mortality patterns though its impact on behavioral strategies and the physical embodiment of distress.
This paper extends the evolutionary understanding of sex differences in mortality rates by quantifying and graphically examining the overall Male to Female Mortality Ratio (M:F MR) for 11 specific leading causes of death across age groups in the USA, over the course of the lifespan in 20 different countries, and across the past 70 years in 5 countries. The resulting quantitative descriptions of rates, trends, and the relative contributions of various proximate causes of death to the M:F MR provide an initial exploration of the risks associated with being male. This analysis also illustrates how sex differences shaped by sexual selection interact in complex ways with multiple aspects of culture and environment to yield a pattern that has some consistency across decades and societies, but also has variations arising from differences among cohorts and cultures. The results confirmed our expectations of higher mortality rates for men than for women, especially in early adulthood, where three men died for every woman who died. For external causes the ratios were even higher. Historical mortality data reflect an epidemiological transition in which discrepancies between male and female mortality rates increase as general mortality rates fall. Cross-national variation in the modern M:F MR further suggests a universal pattern that is influenced by cultural and environmental context. Being male is now the single largest demographic risk factor for early mortality in developed countries.