These quotations from Schrödinger were very perceptive, and raised two key questions. The first is whether the development of the egg is computable, and I will suggest that the answer is no, but that it will be possible to simulate some aspects of development. As regards the second question, how genes control development, Schrödinger could not have known that genes exert their influence through controlling which proteins are made, and in this way they control cell behaviour and development.

In posing these questions, Schrödinger was giving recognition to the fundamental importance of development. Development is at the core of multicellular biology. It is the link between genetics and morphology. Indeed much of the genetic information in our cells is required to direct development. Evolution can be thought of in terms of altering the programme of development so that structures are modified and new ones form.