We are interested in understanding the adaptive significance of behaviour, from underlying neural mechanisms (‘how’, or proximate, questions) through to evolutionary explanations of function (‘why’, or ultimate, questions). The approach is strongly interdisciplinary, using diverse physiological and biomechanical techniques, behavioural experiments, computer modelling, and molecular biology to link from the genetic foundations through to the evolution of behaviour and sensory systems. Mechanistic studies include understanding the functions of nanoscale structures in mechanosensation and the generation and neural control of locomotion. We have major strengths in sensory biology, especially in animal vision (and how it differs from human vision) and acoustics (particularly insect hearing and bat echolocation). Understanding the design and evolution of sensory systems and signals is pivotal to understanding how organisms interact with their environments and each other. Functional questions include integrating theory and experiments to understand how animals make decisions, and what the adaptive value of their decision rules is. The analysis of decision rules extends to understanding the structure and function of animal societies, from studies of mating systems in birds to the division of labour in a million-strong social insect colony.