In The Selective Organism, we encounter a second driver of adaptive evolution: selective production of heritable variation, since the selective process is the developmental decisions made by the organism.

It is typically said that there is natural selection on the genetic variation that affects ecological performance. However, this description of adaptive evolution seems too simple. In The Selective Organism, Pim Edelaar starts with two example studies that cannot be understood using the standard theory of adaptive evolution. This is because traditional interpretations of the three classical requirements for adaptive evolution—variation, selection and inheritance—have been too narrow. The Selective Organism shows how our biological interpretation of each requirement can be expanded. Edelaar integrates these expansions into a visually appealing causal model, and uses it to explore the consequences of this expanded theory of adaptive evolution. This shows that many consequences only involve the quantitative outcomes of the evolutionary process, and several are already wellknown. However, we also encounter a qualitative change in how the evolutionary process can operate: there is now a second driver of adaptive evolution. The first and classical driver, involving natural selection, can be summarized as the 'selective reproduction of heritable variation'. The second driver can be summarized as the selective production of heritable variation, since here the selective process comprises the developmental decisions made by the organism. This expanded theory of adaptive evolution can satisfactorily explain the two puzzling case studies, as well as a diversity of other biological phenomena, such as epigenetic inheritance and cultural evolution. These developments hold important theoretical and philosophical consequences and provide many suggestions for novel and insightful empirical research.