The number of moles may offer an indication of how quickly the body ages, a study suggests.
A sign of slower ageing?
King's College London scientists compared key ageing DNA with the number of moles in a study of 1,800 twins.
They found the more moles a person had, the more likely their DNA was to have the properties to fight off ageing.
The study, in the Cancer Epidemiology Biomarkers and Prevention journal, contrasts with the link between a high mole-count and high skin cancer risk.
Moles appear in childhood and disappear from middle age onwards.
When present in large numbers they can increase the risk of melanoma, a rare form of skin cancer. Moles vary significantly in numbers and size between individuals.
The average number of moles in people with white skin is 30 but some people may have as many as 400.
The reason for such differences between people is unknown as is the function of moles.
Since moles disappear with age, scientists looked at the relationship between the number of moles and telomere length in cells, which is a good indicator of the rate of ageing in organs such as the heart, muscle, bones and arteries.
Telomeres, which get shorter as we age, are bundles of DNA found at the end of chromosomes in all cells and assist in the protection, replication, and stabilisation of the chromosome ends.
They have been compared with the plastic tips on shoelaces because they prevent chromosome ends from fraying and sticking to each other.
In the study, researchers found those with more than 100 moles had longer telomeres than those with fewer than 25.
The difference between the two mole groups was equivalent to six to seven years of ageing.
Lead researcher Dr Veronique Bataille said: "The results of this study are very exciting as they show, for the first time, that moley people who have a slightly increased risk of melanoma may, on the other hand, have the benefit of a reduced rate of ageing.
"This could imply susceptibility to fewer age-related diseases such as heart disease or osteoporosis, for example. Further studies are needed to confirm these findings."
Dr Kat Arney, of Cancer Research UK, said: "While this is an intriguing finding and deserves further investigation, it's important people know that having a large number of moles can increase your risk of skin cancer.
"It's especially important to enjoy the sun safely if you have lots of moles or burn easily."