Can ageing be stopped ?

Gerontologists consider the maximum lifespan for humans to be about 120 years. But with rising evidence for a genetic "death programme," which in principle could be amended, some researchers are starting to believe the limit could be extended.Old age hardly exists in wild animals. Accident, illness or predation usually kill long before the potential lifespan has been reached. Humans, though, especially in the developed world, are pushing in ever larger numbers towards the maximum lifespan, thought by most gerontologists to be around 120. (The world longevity record is held by the Frenchwoman Jeanne Calment, who died in 1997 aged 122 years and 164 days.)In Britain in 1901, life expectancy at birth was 49 for women and 45 for men. By 2002, this had risen to 81 and 76 respectively. This rapid increase in longevity has created hopes among gerontologists not just of an extended "quality of lifespan" well into the nineties, but of lifting the 120-year limit. Ageing science has been divided between optimists and pessimists ever since the first modern theories emerged in the mid-19th century. Pessimists argue that ageing, following the second law of thermodynamics, is caused by the same inevitable decay that afflicts machines and inanimate objects. They accept that biology has evolved repair mechanisms to mitigate the damage, but insist that these merely delay death long enough to ensure the reproductive survival of the organism.

The optimists point out that all animals have immortal reproductive cells ("germlines"), and argue that ageing and longevity are genetically determined through programmes that can in principle be amended. They argue that biology has the tools to cope with wear and tear almost indefinitely, if only there were an evolutionary route to get there. Right now the optimists are in the ascendant, bolstered by recent experiments that have extended the life expectancy of mice from around two years to three, with some reports of up to five. Such progress is unlikely in humans, for whom evolution has already boosted maximum lifespan well beyond comparably sized mammalsincluding great apesbut the work sheds valuable light on some of the mechanisms involved. The recent progress in mice was made by the application of the discovery, dating back to the 1930s, that lifespan could be increased dramatically in almost all animals by a diet low in calories but comprising all vital nutrients. This remains the one proven strategy for boosting life expectancy and slowing down ageing across a wide range of species. (On this basis, occasional fasting, as practiced in some religions, might well extend human lifespan.)
View: Full Article | Source: Prospect Magazine