The observation that people with more moles on their bodies tend to show fewer signs of skin aging — fewer wrinkles, more youthful-looking skin — had been noted by dermatologists for years before researchers at King's College London published a study in 2007 that provided a possible biological explanation.

The researchers found that the skin cells of people with many moles contained longer telomeres than the skin cells of people with few moles. Telomeres are the protective caps at the ends of chromosomes that shorten with each cell division — a biological clock that measures cellular aging. Longer telomeres are associated with slower cellular aging and, broadly, with longevity. The finding suggested that the same biological mechanism that produces moles might also confer resistance to cellular aging.

The research attracted considerable popular interest because it offered a potential explanation for something anecdotally observed — that some people seem to age more slowly than their chronological age would predict — and because it suggested a biological marker that might identify people at the slow-aging end of the distribution before the aging itself became visible.

The clinical implications were carefully hedged by the researchers themselves. The association between moles and longer telomeres does not mean that having moles protects against aging; it might mean that some underlying biological process produces both more moles and longer telomeres. The direction of causality and the practical implications for skin care or anti-aging intervention remained unclear.

What the research added to the scientific understanding of aging was another data point in the complex picture of telomere biology — a field whose early promise as a key to understanding (and eventually slowing) human aging has been partially fulfilled and more broadly complicated by subsequent research.