Evidence from global data that human longevity is at the expense of reproductive success
The decline in survival and fecundity that occurs with increasing adult age is often seen as an evolutionary result of the decreasing force of natural selection as we age (17; 22). The accumulation of deleterious late mutations (17; 12; 4) and/or pleiotropy as a result of life-history optimization constraints can lead to ageing. As an example, increased allocations of limited resources towards reproduction can lead to senescence or later mortality (17; 35; 14; 15; 31). The majority of evidence for this phenomenon is from experiments that show the negative consequences of increasing reproductive effort on lifespan (21, 32, 3, 10 ), The reverse effect of artificial selection on age of reproduction was that the selection regime that favoured individuals who retained fecundity later in life resulted populations with longer lives (7, 39, 22). For higher organisms such as mammals, data are lacking. Mammals have been largely absent until now.
Homo sapiens were recently tested to test the hypothesis that investing in reproduction decreases resources available for somatic upkeep. They used 1,200 years’ worth of genealogical information on British aristocracy to show that the number progeny of women who die at a young age is low, increases with age, reaches a plateau in the sixth, seventh, and eighth decade of life and then drops again for those who die at 80 or older. This relationship supports the hypothesis that high investments in reproduction divert resources from maintenance and repair of the cells, resulting in ageing and an earlier death (33). The authors discovered that men showed a similar pattern for unknown reasons.
Since manipulative experiments with humans are not ethical, statistical searches for congruent patterns offer an alternative way to understand variations in life-history characteristics among human populations. There are many statistics about humans and their actions, so it is possible to detect similar patterns or test relevant hypotheses. This paper aims to determine the extent of this tradeoff in humans. We examine whether the variations in life-history characteristics found among British aristocrats are also observed across human populations around the world. We used data from 153 different countries to determine the relationship between fecundity and longevity.
Source:
https://onlinelibrary.wiley.com/doi/full/10.1046/j.1420-9101.2000.00190.x
