There is much more to both evolution and development than we can learn from focusing primarily on genes. However, this realisation is hard won, given the recent history of biology, and of philosophy of biology. I noted in Chapter 4 that the twentieth century witnessed the biological reconceptualisation of evolution in terms of changes in gene frequencies in a population, and of development in terms of gene expression. Moreover, although philosophers have long been preoccupied with evolutionary theory, and more recently with molecular biology, they have engaged far less frequently with development. Whereas historians of biology have been long intrigued by embryology, philosophers have tended to shy away. Yet times have changed. It is mainly as a result of recent work in developmental and molecular biology that some of the reductionistic biases of genetics have paradoxically come to be seen as constricting future research and precluding genuine understanding of both development and evolution.