Theories of Life-History Evolution

In order to assess current scientific understanding of life-historyevolution, the alternative fundamental theories are formulatedin a refutable form and compared with the available empiricalevidence. The hypothesis that life-history does not evolve isrejected on the grounds that life-history can be readily modifiedby artifical selection. The hypothesis that life-history evolvesaccording to mechanisms other than natural selection actingon genetic variation is shown to have no sound experimentalbasis. The hypothesis that life-history evolution depends primarilyon group selection is undermined by the absence of the predictedgroup adaptations. The hypothesis that life-history is a unitarycharacter which evolves in the same fashion as fitness is rejectedbecause of the disparity between life-history genetics and basictheory concerning the evolution of fitness. The hypothesis thatlife-history is composed of a set of autonomous characters whichare subject to mutation accumulation at later ages is refutedby the lack of any detectable increase in genetic variabilitywith age and the evidence for the interdependence of life-historycharacters. It is concluded that the hypothesis of antagonisticinteractions between life-history characters, generalized totake genetic variability into account, is the most satisfactorytheory of life-history evolution available.