‘Couch potatoes more docile’

Likewise,researchers now recognise that many animals have “personality”,in that they display consistent differences in behaviours.

According to Dr Biro,it is significant that those behaviours often relate to the rates at which they acquire and expend energy through feeding or activity.

“Some of us are couch potatoes while others are drawn to sport and exercise. We often associate the athletic ‘jock’ type or person with being aggressive and social,whereas the more sedentary ‘nerd’ often is seen as more socially awkward and submissive.

“These are generalisations,but most people would probably agree there is some truth to them. If so,why should individuals differ in their propensity for activity and in their personality,and why might they be related?” he said.

The study,published in the ‘Trends in Ecology and Evolution’ journal,reviews a wide range of recent research into these questions and concludes that there is now enough evidence to suggest a link between an individual’s personality and the rate of metabolism — the chemical process converting food into the energy that fuels the body.

“Animals in captivity often engage in energetically demanding behaviour when they have unlimited food available. Mice spend considerable time on running wheels,for example,and other animals often pace back and forth in zoo enclosures.

“Given they don’t need to move about in search of food as they would in nature,we might ask why they are apparently ‘exercising’,” Dr Biro said.

The amount of energy devoted to energetically demanding activities differs among individuals,Dr Biro said.

“It may just be that some individuals generate much more energy than others and when those individuals are captive with abundant food,they must outlet ‘excess’ energy that is normally expressed in nature in activities such as feeding and defence of food supplies.

“We are still some ways from a really solid understanding of the links between metabolism and personality in animals,but recent research suggests these ideas have merit and are worth studying further,” he said.