Natural selection according to Darwin: cause or effect?

Abstract

AbstractIn the 1940s, the ‘modern synthesis’ (MS) of Darwinism and genetics cast genetic mutation and recombination as the source of variability from which environmental eventsnaturally selectthe fittest, such ‘natural selection’ constituting the cause of evolution. Recent biology increasingly challenges this view by casting genes as followers and awarding the leading role in the genesis of adaptations to the agency and plasticity of developing phenotypes—making natural selection a consequence of other causal processes. Both views of natural selection claim to capture the core of Darwin’s arguments inOn the Origin of Species. Today, historians largely concur with the MS’s reading ofOriginas a book aimed to prove natural selection thecause(vera causa) of adaptive change. This paper finds the evidence for that conclusion wanting. I undertake to examine the context and meaning of all Darwin’s known uses of the phrasevera causa, documenting in particular Darwin’s resistance to the pressure to prove natural selection avera causain letters written early in 1860.His resistance underlines the logical dependence of natural selection, anunobservablephenomenon, on the causal processes producing theobservableevents captured by the laws of inheritance, variation, and the struggle for existence, established in Chapters 1–3 ofOrigin.