Tuesday, June 15, 2010

Mating Competition and Mortality Rates

If you head over to this web page you can find the chart posted above which illustrates the difference in health and life expectancy for men and women in Canada.

Why is it that men have higher mortality rates than women?

This article in the latest issue of Evolutionary Psychology suggests that the answer is- mating competition.

The press release for the paper explains: "women invest more physiologically in reproduction than men, thus men compete with other men for mating partners and try to make themselves attractive to women. This competition leads to strategies that are riskier for men both behaviorally and physiologically, and these result in higher levels of mortality".

Here is the abstract:

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.

And this comment from the conclusion is worth noting, and is important for political philosophers:

.... despite the potential benefits of economic leveling interventions, any effort to substantially reduce variations in wealth and resource control will likely face considerable political opposition. Paradoxically, opposition to such redistributions will be especially prevalent from men. Due to the long association of male status and reproductive success in our evolutionary history, men are both more sensitive to their position in the social hierarchy as well as to perceived threats to their relative status. The fragility of socialist utopias such as the Paris Commune of 1871 and other communities intentionally suppressing status differentials reveals the difficulty in sustainably implementing such social structures. Edward O. Wilson once remarked that “Karl Marx was right, socialism works; it is just that he had the wrong species” (Novacek, 2001). In sum, this study contributes to the growing body of literature demonstrating the substantial benefits that the evolutionary framework offers for understanding social patterns and important social issues.

This last point provides perhaps an interesting response to Cohen's question "If You're An Egalitarian, How Come You Are So Rich"? Answer: because our interest in sex outweighs our interest in an egalitarian ethos.

I'm not saying this is a morally justified response. But it further illustrates how important it is for political philosophers to take human nature seriously. The factors at play in our psychology are much more complex than simple greed. Rather than focusing on just market incentives (which is Cohen's focus), the egalitarian ought to dig deeper and consider the impact mating competition has played (and continues to) on our psychology.