The shaping of senescence in the wild

A central prediction of classical theories of senescence states that environments posing a high risk of mortality favor the evolution of rapid intrinsic deterioration, or ageing. Although widely cited as being largely corroborated by existing data, empirical support for this prediction has been mixed. Recent theory suggests that this expectation should only be realized under particular circumstances, and this could account for the equivocal empirical findings. Here, we highlight the salient features of some of the recent developments in this field and suggest some ways in which progress might be made. We argue that it is necessary to move beyond the simplistic classical expectation and to take a more comprehensive and precise approach to studies of senescence, both theoretically and empirically.