It is, on the face of it, a frankly random connection, as random as the distribution of those highly pigmented blotches - yes, often on faces (see Scarlett Johansson) - tends to be. But the answer, according to researchers at King's College, London, is yes. The effect is even quantifiable: if you have always resented your 100-plus moles, you can now take comfort from the fact that you will probably live six or seven years longer than someone with only 25 or so of the pesky things. That is, if a malignant melanoma doesn't get you first.

For that was where the connection was first observed - among clinical dermatologists looking after what lead researcher Dr Veronique Bataille calls "moley people", moles being an important risk factor for melanoma. The dermatologists noticed that "if you had a lot of moles, you were less likely to get age spots and wrinkles and all the signs associated with chronic sun-damage and ageing. There was already a clinical suspicion that something was different."

The answer - 15 years of research (and more than 900 sets of twins) later - was to be found in telomeres, strands of inactive DNA at the ends of each of our 46 chromosomes. They are at their longest when we are born, and shorten as we age; the shorter they are, the less time we have left.

The twist is that they shorten at different rates, depending on what else is going on: genetic inheritance, for example, or early heart disease - or some environmental factors: smokers tend to have shorter telomeres; one recent, controversial study claimed that poor people did too. People with lots of moles tend to have longer telomeres than people of the same age with fewer moles. So count - literally - your blessings. Unless, of course, they get larger, or start to itch.