Human Life History Variation and Sex Differences in Mortality Rates

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.