Evolutionary and cultural factors in men's health

Townsend Letter for Doctors and Patients,  Dec, 2004  by Tim Batchelder

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This month, I am writing from Paris as part of a meeting on medical communications in Geneva. In traveling, I have given some thought to different cultural and environmental variables that affect men's health globally. Numerous French anthropologists have long been interested in the role of culture in shaping human behavior and health. Marcel Mauss, founder of the Institute of Ethnology of the University of Paris, studied human societies as total systems, self-regulating and adaptive to changing circumstances in ways designed to preserve the integrity of the system. Mauss exerted considerable influence over such disparate figures as Claude Levi-Strauss in France and Bronislaw Malinowski and A.R. Radcliffe-Brown in England. These early anthropologists pointed out the health promoting properties of traditional cultures in which there were few of the stressors that increase male mortality today and their work inspired much of the artistic and creative counter-culture that thrived in Paris in the first half of the 1900s.

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However it is not until recent years that anthropologists have pulled together bio-cultural data to develop solid theories on the anthropology of men's health. The key discovery of anthropologists on men's health focuses on the greater risk of men for dying from a variety of causes and the bio-cultural drivers of this tendency. A recent study by Kruger and Nesse (2004) provides the basis for this review drawing on pioneering cultural and bio-behavioral research in 20 countries. By better understanding the anthropology of men's health, we can move towards a more holistic, less pharmacologically based, approach to male health problems.

Kruger and Nesse (2004) note that the discrepancy between male and female mortality rates, recognized since at least 1750 (Kalben, 2000), has been explained by an array of biological and behavioral causes (Hazzard, 1990; Kraemer, 2000). In species where females make a greater parental investment, they tend to be more discriminating in mate choice, so the reproductive success of males depends largely on their ability to compete for mating opportunities (Trivers, 1972), either by winning fights with other males or by presenting displays preferred by females (Darwin, 1871). The fitness benefits of these outcomes tend to increase the prevalence of genes that promote male risk-taking and competitive ability at the expense of decreased investment in repair capacity and disease prevention (Daly and Wilson, 1978). This is the evolutionary reason why females live longer on average in most animal species (Hazzard, 1990).

Compared to women, men tend to have greater height and weight, more upper-body strength, higher metabolic rates, higher juvenile mortality, later sexual maturity, and shorter life-spans (Cronin, 1991). The role of sexual selection is supported by the high correlation between excess male mortality and sexual size dimorphism across mammalian taxa, after controlling for the effects of phylogeny (Promislow, 1992). Some increased risk results directly from the increased vulnerability of male structural, physiological, endocrinological, and immunological systems, especially lower resistance to infection, injury, stress and degenerative diseases (Folstad and Karter, 1992; Hazzard, 1990). Male mammals are also more likely than females to have parasites (Moore, 2002), both because of the immunosuppressive effects of testosterone and because their bodies are simply larger (Folstad and Karter, 1992). Infection or parasites kill twice as many men as women in developed countries, four times as many in undeveloped countries (Owens, 2002). Hamilton and Zuk (1982) have proposed that females are sensitive to physiological cues reflecting parasite loads in potential male mates, with the exemplar being female birds that prefer brightly colored males. Men are also more susceptible than women to mortality stemming from cold winter months. (Rau and Doblhammer, 2003).

Kruger and Nesse also note that sexual selection helps to explain some differences in behavioral tendencies, including risk-taking, competitiveness, and sensitivity to hierarchy (Cronin, 1991). Greater male than female variation in reproductive success means that risk-taking has higher payoffs for males as they compete for resources, social status, and mates (Daly and Wilson, 1985).

Special selection pressures faced by females may also have increased sex differences in the tendency for engaging in risky behaviors. The costs of risk-taking tend to be higher for women because offspring survival depends more on maternal than paternal care and defense (Campbell, 1999). This notion fits quite well with the recent recognition of sex differences in behavioral responses to stress. Rather than the "fight or flight" behavior that may characterize male behavioral reactions to adverse circumstances, the female behavioral pattern is thought to resemble a "tend-and-befriend" response where nurturant tending activities protect and reduce distress in oneself and offspring and safety and befriending activities create and maintain social networks facilitating this process (Taylor, Klein, Lewis, Gruenewald, Gurung, Updegraff, 2000).