Darwinian Evolution

Abstract

This chapter describes the emergence of modern evolutionary thought. It begins with Lamarck’s transformational theory of evolution, a theory dependent upon core metaphysical assumptions. Darwin’s triumph was the removal of those assumptions, through the pursuit of empirically derived scientific axiom and the introduction of population thinking. Nonetheless, he was unable to do more than black box the mechanisms of variation and inheritance essential to his theory of evolution by natural selection. This left the field open for differing positions on whether evolution was a gradual process, and whether variation was continuous. With the emergence of quantitative biology and statistical methods of analysis a long debate between Darwinian gradualists, committed to continuous variation, and saltationists who thought variation was discontinuous began. The rediscovery of Mendel’s particulate model of inheritance in 1900 enhanced the saltationist position, even though there is some evidence Mendel saw continuous variation as underpinned by particulate inheritance. It was the resolution of this debate that has been regarded as the beginning of the Modern Synthesis in evolutionary biology, and so this chapter ends at this point. The Modern Synthesis is the focus of the following chapter.