"When I was a child, one of my favourite books was Bear, Mouse and Water Beetle," says Tom Shakespeare. "Today, I want to tell you a contemporary story, which you could call Fly, Fish, Mouse and Worm."

These 'model animals' help scientists to understand the basic processes common to all living creatures. But while model animals epitomize the success of the scientific strategy of reductionism, they may also illustrate the downside.