Unnatural deaths among nuns and monks: is there a biological force behind male external cause mortality?

It is still unclear if and how biological factors contribute to excess male mortality due to 'external causes' (accidents, injuries, homicides and suicides). Sex hormones and reproductive roles are supposed to drive sex differences in behaviours increasing the male external cause mortality risk. This study analyses the external cause mortality of Catholic nuns and monks from three Bavarian cloisters whose similar environments allow the impact of biological factors to be isolated from a number of confounding causes. Using obituaries, entries in the profession books of religious orders and cemetery registers 2533 deaths of nuns and monks could be linked to a specific cause of death for the years 1946-2005, of which 69 belong to the group of external cause deaths. External cause mortality of the Bavarian cloistered and the West German general population has been compared by means of standardized mortality rates (SMRs) for ages 45 onwards using the European age standard for the age groups 45-64, 65-74 and 75+. Whereas nuns show statistically significantly lower external cause mortality than the general female population, monks' external cause mortality parallels or even exceeds that of general population males. These findings contradict the reproductive role hypothesis and provide some evidence for the sex hormones hypothesis.