Abstract

Empirical advances in biology led to the popularity of a view known as gene selectionism, most recently championed by Richard Dawkins' "The Selfish Gene" . On this view, natural selection "looked through" the organism right to the genome; evolution was a change in the genomes of a species over time and the process of development is rendered epiphenominal to that process. Recently, support for gene selectionism has waned in favor of a pluralistic view. On this view, natural selection operates at many different levels, including: genes, traits of organisms, organisms, groups, species and clades. Because the process of development occurs at many of these levels, a complete understanding of evolution will include an understanding of the developmental process. This dissertation is a contribution to the integration of evolution and development that has become known as the developmental synthesis. ;I argue that the adaptationism debate has raged for so long because it is based on an incoherent picture of the world, according to which, some traits are due to natural selection and others are due to constraints. In fact, all traits are due to both natural selection and constraints. Whether we explain a trait in terms of natural selection or constraints is a matter of pragmatics. Evolutionary explanations are causal explanations and different types of evolutionary explanations appeal to different aspects of the evolutionary process. ;I also offer two general theories on how natural selection can design organisms capable of complex development. The first focuses on the nature of gene control networks. I argue that they are connectionist networks designed by natural selection to overcome the difficulty of development. The second focuses on the evolvability of ontogeny. I argue that ontogeny can be designed by natural selection for increased evolvability, primarily through designed functional modularity