By isolating and identifying the gene, researchers hope they may be able to devise treatments that could slow the process of ageing.
A team led by Dr Gerard Schellenberg at the Veterans Health Care System, in Seattle, together with the Darwin Molecular company, reports the gene's discovery in today's issue of the US journal, Science.
They discovered the gene by looking at people with Werner's syndrome - a form of premature ageing - which results from inheriting an abnormal variant of the gene. There are an estimated 1,000 people with Werner's syndrome in Britain, according to Professor Sydney Shall, an expert on the disease at Sussex University. The average age of death is 45, but some last until their 50s.
Professor Shall suggested Werner's syndrome may have been the primordial human standard, while "normal" people evolved the extra gene to acquire our present longevity.
The gene appears to slow ageing. "What if we put in another one?" he asked. "One hundred and fifty years is not an unreasonable human lifespan and we are talking about healthy, vigorous life, not sick old people, not 25 years of sitting in a bath chair."
Scientists have already transplanted genes to correct inherited diseases, such as cystic fibrosis.
People with Werner's develop normally until they are about 10, when they stop growing. By their 30s they have severe atherosclerosis - narrowing of the arteries associated with old age, and can develop diabetes, cancer, osteoporosis and rheumatoid arthritis.
n Men who find themselves becoming grumpier and more forgetful as they grow older may now have an explanation.
Researchers at the University of Pennsylvania found that men's brains shrink as they grow older, with slowing of response time and a loss of sense of humour.
The shrinkage apparently occurs only in men and can begin in the twenties
Neuropsychologist Ruben Gur said menspen most of their time activating a certain part of their brain.It is likely that this is the partthat will suffer most of the consequences."Reuse content