Scientists now recognize that many animals exhibit personality, behavioral displays known as “consistent individual differences.”    Peter Biro, from the University of New South Wales (Australia) and colleagues reviewed a wide range of recent research and posit that there is now enough evidence to suggest a link between an individual's personality and the rate of its metabolism – the chemical process that converts food into the energy that fuels the body. The researchers investigated why individuals differ in their propensity for activity and in their personality, and why these two factors may be related. They found that behaviors often relate to the rates at which an individual acquires and expends energy through feeding or physical activity.