A DIRECT link has at last been found between an animal’s lifespan and the size of DNA sequences called telomeres in their chromosomes. But contrary to expectation, it’s the rate at which telomeres shorten that matters, rather than their length. The finding is important because telomeres play a key role in cancer and ageing.
Telomeres are repetitive DNA sequences found at the ends of every chromosome. They normally shorten each time a cell divides. When they become too short the cell stops dividing and eventually becomes moribund. So telomere length sets an upper limit on the number of divisions a…
