The Active Role of Behaviour in Evolution

Abstract

The various ways in which the behaviour of animals might have changed the course of evolution have become serious areas of inquiry. Four major proposals have been made for the ways in which an animal’s behaviour could affect subsequent evolution (Bateson 1988; Wcislo 1989). The new book of essays edited by Weber and Depew focuses on just one of these and is particularly concerned with the role of learning in the evolution of cognitive capacities. Even so, it is worth drawing out the distinctions since writers, including many in this book, often blur them. First, animals make active choices and the results of their choices have consequences for subsequent evolution. Second, by their behaviour, animals change the physical or the social conditions with which they and their descendants have to cope and thereby affect the subsequent course of evolu- tion. Third, animals are able tomodify their behaviour in response to changed conditions; this allows evolutionary change that otherwise would probably have been prevented by the death of the animals exposed to those condi- tions. Finally, by their behaviour animals often expose themselves to new conditions which may reveal heritable variability and open up possibilities for evolutionary changes that would not otherwise have taken place. I shall consider each of these ideas in turn. Active