Human longevity at the cost of reproductive success.

The disposable soma theory on the evolution of ageing states that longevity requires investments in somatic maintenance that reduce the resources available for reproduction. Experiments in Drosophila melanogaster indicate that trade-offs of this kind exist in non-human species. We have determined the interrelationship between longevity and reproductive success in Homo sapiens using a historical data set from the British aristocracy. The number of progeny was small when women died at an early age, increased with the age of death, reaching a plateau through the sixth, seventh and eighth decades of life, but decreased again in women who died at an age of 80 years or over. Age at first childbirth was lowest in women who died early and highest for women who died at the oldest ages. When account was taken only of women who had reached menopause, who were aged 60 years and over, female longevity was negatively correlated with number of progeny and positively correlated with age at first childbirth. The findings show that human life histories involve a trade-off between longevity and reproduction.