Reexamining the association between fertility and longevity: Testing the disposable soma theory in a modern human sample of twins

Abstract

The disposable soma theory proposes a trade-off between fertility and longevity but existing findings on this association have been mixed. This study used data from 15,622 twins born between 1901 and 1925 ascertained from the population-based Swedish Twin Registry to test the child-longevity association and whether it is accounted for by individual-level factors or by genetic and environmental factors shared by family members. Based on survival analysis, both women and men with children had significantly longer survival relative to the childless, with a slightly higher relative advantage in men. Adjustments for demographic factors and cotwin fertility did not mediate the parenting-survival association, indicating that this association is attributable to individual-level factors associated with fertility rather than family-level environmental or genetic factors shared by cotwins. These results, derived from a large, population-based sample, are inconsistent with the disposable soma theory as applied to modern human populations. © 2013 The Author.