 The role of mathematics in the explanation of musical phenomena has been explored since Antiquity, and that of physics has become prominent since the seventeenth century. In the second half of the nineteenth century, scholars began to examine the relation of music to the life sciences. A major force behind this shift of attitude is the work of Charles Darwin (1809–1882). His theory of evolution posits two main processes responsible for changes in a living species, natural selection and sexual selection. Individual variability and random mutations introduce differences in the traits possessed by different individuals belonging to the same species. Traits that favor the survival of offspring who would themselves go on to reproduce are more likely to reappear in future generations. This is natural selection. Sexual selection concerns the selection of mating partners. Widespread preference for a given trait means that future generations will be more likely to possess that trait. In both cases, the traits in question must be heritable.