Understanding sex differences in mortality rates with an evolutionary life history framework

Daniel J Kruger, University of Michigan
Randolph M Nesse, University of Michigan

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. We graphically depict how sex differences in mortality rates across age and cause can be understood in the context of life history allocation of somatic and reproductive efforts. Excess male mortality is a result of a trade-off between competitiveness and longevity. Social and environmental conditions intensifying male competition for resources, status, and mates lead to increased male mortality through riskier behavior patterns and the impact of stress on physiological susceptibility. These patterns confirm our predictions derived from evolutionary theory and indicate that the sex difference in mortality rates is an important life history indicator related to population reproductive patterns. The fact that the M:F MR is not genetically determined and is affected by social conditions encourages intervention efforts to reduce excess male mortality.