This is the story of one of the most unlikely scientific pioneers of our age: the laboratory mouse. The mouse has been involved in many of the great medical breakthroughs of the last century. From the development of penicillin to transplant surgery, research carried out on mice has played a crucial part in treating millions of people.

 DIRECTOR INTERVIEW
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In the last four years exploration of human genetics has been pushed forward by work on the mouse genome. The genes that man and mouse share are 99% identical. Research is being conducted on these animals to help pinpoint the human genes responsible for alcohol addiction and sleep disorders. But it is also giving insight into some of the genes which control human intelligence and memory.

What impact is the research having on current medical decisions? Some members of Leah Wilkinson's family are affected by an inherited learning difficulty. Leah has waited 17 years to find out whether she is carrying the mutant gene which causes the condition. Now, as a result of work on mouse genetics, she has been able to find out that she is not a carrier and in her late thirties is planning to have a family for the first time.

And in America, scientists think they are on the track of a mouse gene responsible for slowing down the effects of ageing in humans. They hope it could signal the way for a golden old age of humanity.

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