The promise of behavioural biology

The studies of behaviour that were strongly rooted in biology have had a long tradition of bringing together the 'how' and the 'why' questions. This integrative approach will serve the subject well in the postgenomic era as the long trend towards analysis at lower and lower levels starts to reverse. The new studies will make use of the resources uncovered by molecular biology and the neurosciences but will use the behaviour of the whole animal to measure outcomes and the context in which behaviour occurs to frame analytical questions. Two examples are given of how movement between levels of analysis is being used with increasing power and promise. The first is the study of filial imprinting in birds where many of the molecular and neural mechanisms involved have been uncovered and are now being integrated to explain the behaviour of the whole animal. The second is the triggering during sensitive periods in early life by environmental events of one of several alternative modes of development leading to different phenotypes. (C) 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.