Antagonistic pleiotropy is the tendency for a gene that is advantageous in youth to cause problems in later life - evolution selects for it despite the later cost. The trade-off between fertility and longevity might be thought of in this way, as the delayed cost of mechanisms that increase youthful fertility: "Aromatase (CYP19) and estrogen receptor-alpha (ESR1) are involved in the metabolism of estrogens, which have a relevant role in female and male aging. Moreover, due to their influence on fertility, both genes may be part of the longevity-fertility trade-off mechanism. This investigation examines the association of [ESR1 and CYP19 polymorphisms] with longevity. A sample of 258 individuals (mean age = 83.1 +/- 5.7 years) was recruited in 2000. Based on mortality data collected in 2009, the sample was divided into two groups of participants surviving more than 90 years or not. The analysis showed that ESR1 PP and CYP19 genotypes carrying the T allele were significantly associated with longevity (survival to age more than 90 years). As the ESR1 PP genotypes were found associated with reduced fertility in the same sample, we may infer that ESR1 genotypes could exert an antagonistic pleiotropic effect on longevity and fertility."