Someone to live for: effects of partner and dependent children on preventable death in a population wide sample from Northern Ireland

How to allocate resources between somatic maintenance and reproduction in a manner that maximizes inclusive fitness is a fundamental challenge for all organisms. Life history theory predicts that effort put into somatic maintenance (health) should vary with sex, mating and parenting status because men and women have different costs of reproduction, and because life transitions such as family formation alter the fitness payoffs from investing in current versus future reproduction. However, few tests of how such life history parameters influence behaviours closely linked to survival exist. Here we examine whether specific forms of preventable death (accidents/suicides, alcohol-related causes, and other preventable diseases) are predicted by marital status and dependent offspring in a modern developed context; that of Northern Ireland. We predict that men, non-partnered individuals and individuals who do not have dependent offspring will be at higher risk of preventable death. Running survival analyses on the entire adult population (aged 16-59, n = 927,134) controlling for socioeconomic position (SEP) and other potential confounds, we find that being single (compared to cohabiting/married) increases risk of accidental/suicide death for men (but not for women), whereas having dependent children is associated with lower risk of preventable mortality for women but less so for men. We also find that the protective effect of partners is larger for men with low SEP than for high SEP men. Findings support life history predictions and suggest that individuals respond to variation in fitness costs linked to their mating and parenting status.