Extrinsic mortality and the evolution of senescence

Abstract

In a valuable recent article in TREE about senescence in the wild, P.D. Williams et al. [1] summarized experimental and observational evidence bearing on a prediction, by G.C. Williams [2], of the impact of mortality on the evolution of senescence. Medawar [3] and Williams [2] argued, and Hamilton [4] demonstrated, that the selection gradient on age-specific mortality declines with age, a result (‘slope theorems’ [5] or ‘Hamilton's indicators’ [6]) that provides the basis for evolutionary explanations of senescence via either antagonistic pleiotropy or mutation–selection balance.