JOHN R. Speakman is Professor of Zoology at the University of Aberdeen, Scotland, and Head of the Division of Appetite and Energy Balance at the Rowett Institute, also in Aberdeen. He is a leading figure in the field of animal energetics. His research interests include the causes and consequences of variation in energy expenditure of a wide range of animals from bats and other small mammals to dolphins and turtles. In 1996 he received the Zoological Society of London Scientific Medal for his work on energetics and in 2000 was a Royal Society Leverhulme Senior Research Fellow.