If we wish to foster a dialogue between evolutionary biology and developmental biology, we need to ensure that the two disciplines stand on equal metaphysical footing. I think that developmental biology is still heavily biased by finalism, whereas an equation of evolution to progress is by now a matter of the past. A discussion of this problem and some suggestions for a new view of development was the subject of chapter 1.

In this view, development acquires a meaning of its own, rather than simply being the process required to obtain an adult. Consequently, I have suggested that the very origin of many, if not most, of the basic features of an animal's body must be searched for in the adaptive significance these features initially had for development as such, rather than as adult features necessarily prepared through development. This idea was the subject of chapter 2.

If development is not the way by which a programme encoded in the egg is deployed to reach the final, adult condition, we may question whether the metaphor of the programme (more precisely, the metaphor of the genetic programme) is indeed adequate. I think it is not. This is not to deny, of course, the role of genes in development, but to question instead current notions such as the developmental gene and the master control gene. I am sympathetic towards those views according to which the development of the earliest multicellular organisms was mainly caused by generic, rather than genetic, causes.