'Time waits for no man, the old truism goes, but in recent years scientists have shown that it does seem to move more slowly for some. Molecular biologists have observed that people's cells often age at different rates, leading them to make a distinction between chronological and biological age.
'But the reason for the difference remains only vaguely understood. Environmental factors such as smoking, stress and regular exercise all seem to influence the rate at which our cells age. Now, for the first time, researchers have found a genetic link to cellular aging — a finding that suggests new treatments for a variety of age-related diseases and cancers.
'The field of biological aging has in recent years focused on the long molecules of DNA contained in human cells called chromosomes. All chromosomes have protective caps at either end called telomeres. Each time a cell replicates itself (as it does before it dies), the telomeres shorten, like plastic tips fraying on the end of shoelaces. Shortened telomeres have been linked to a host of age-related illnesses such as heart disease and certain cancers. (Scientists have yet to study whether telomeres influence a person's appearance.) Last year's Nobel Prize for Medicine was awarded to three American scientists for their work in the field, and many scientists now believe that telomeres are the closest we may come to identifying a biological clock — and our best bet for learning how to stop or turn back that clock.'
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