SYNOPSIS. In order to assess current scientific understanding of life-history evolution, the alternative fundamental theories are formulated in a refutable form and compared with the available empirical evidence. The hypothesis that life-history does not evolve is rejected on the grounds that life-history can be readily modified by artifical selection. The hypothesis that life-history evolves according to mechanisms other than natural selection acting on genetic variation is shown to have no sound experimental basis. The hypothesis that life-history evolution depends primarily on group selection is undermined by the absence of the predicted group adaptations. The hypothesis that life-history is a unitary character which evolves in the same fashion as fitness is rejected because of the disparity between life-history genetics and basic theory concerning the evolution of fitness. The hypothesis that life-history is composed of a set of autonomous characters which are subject to mutation accumulation at later ages is refuted by the lack of any detectable increase in genetic variability with age and the evidence for the interdependence of lifehistory characters. It is concluded that the hypothesis of antagonistic interactions between life-history characters, generalized to take genetic variability into account, is the most satisfactory theory of life-history evolution available.