Longevity and the costs of reproduction in a historical human population.

It has been argued that the priority that natural selection places on reproduction negatively affects other processes such as longevity and the problem posed by this trade-off underlies the disposable soma theory for the evolution of human ageing. Here we examine the relationship between reproduction and longevity in a historical human population (the Krummhörn, north-west Germany 1720-1870). In our initial analyses, we found no support for the hypothesized negative effects of reproduction on longevity: married women who remained childless lived no longer than women who reproduced and women who had few children lived no longer than women who had many children. However, more detailed analyses in relation to socio-economic class revealed that the extent to which reproduction has an effect on longevity is a function of the level of economic deprivation. We found that, when possible sources of confound were controlled for (e.g. duration of marriage and amount of time spent in fecund marriage), there is an increasingly strong relationship between longevity and reproduction with increasing poverty.