An evolutionary life-history framework for understanding sex differences in human mortality rates

Abstract

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.

A Survey of Non-Classical Polyandry

“…For example, we found an association between male productive labor time and high adult male mortality and polyandry (reported and discussed below). Cross-culturally, however, male productive labor time (Ember 1983) and mortality rates (Kruger and Nesse 2006) are greater than female labor time and female mortality. Nevertheless, if no trends are found in the polyandrous societies we examine, the factors we identify as hypothetical determinants of polyandry are probably not worth pursuing in a more inclusive cross-cultural sample.…”

Fluctuating asymmetry in dental and mandibular nonmetric traits as evidence for childcare sex bias in 19th/20th century Portugal

“…Despite greater male susceptibility to mortality, morbidity, vulnerability and risk taking (factors that usually are not evident until adolescence: Kruger and Nesse, 2006), females in the past have been reported to be particularly susceptible to mortality, morbidity and stress due to the socio-cultural preferential treatment of males (Bigoni et al, 2013;Goodman et al, 1987;Guatelli-Steinberg et al, 2006;May et al, 1993;Šlaus, 2000). Such male preferential treatment is particularly prevalent in poverty-ridden underdeveloped countries (Goodman et al, 1987;May et al, 1993) like Portugal in the 19 th and early 20 th centuries.…”

Evolutionary Perspectives on Violence, Homicide, and War

“…Th erefore, it is not surprising that men around the world are substantially more physically violent than are women. In the United States, roughly 87% of those who commit homicide, and 75% of those who fall victim to homicide, are men (Lester, 1991), a statistic that is similar, if not even more male biased, in other countries (Buss, 2005;Daly & Wilson, 1988;Ghiglieri, 1999Additionally, the levels of mortality from violence are highest in young adulthood and decrease considerably as men marry, start families, and invest in their children, that is, when the search and competition for mating opportunities decreases (Kruger & Fitzgerald, Chapter 10, this volume;Kruger & Nesse, 2006). Although other factors may play a role in the high rates of violence among young men, the consistently higher mortality rate across the lifespan for men who have never married compared with men who have supports the idea that intrasexual competition is an important factor at any age in which a man is looking for a mate.…”

“…For example, men are most likely to engage in a fast strategy during young adulthood, defi ned by the peak of risky and violent behavior in this age group (Kruger & Nesse, 2006). Across species, the preferred strategy varies as a function of unpredictability in the environment, with uncertain conditions fostering a fast strategy.…”

“…Th is logic can also explain individual diff erences in human violence, particularly among men. In the United States, the sex diff erence in mortality rates is higher for those in lower income groups and those with low educational attainment, both factors that infl uence one's certainty of future success (Kruger & Nesse, 2006). Across societies, male mortality is disproportionally higher when economic inequality is greater (Kruger, 2010).…”