Methuselah decoded

Correction: The study which this article reports has been officially retracted. This was added on August 9th, 2011.

Correction to this article

IN PURSUIT of a long life, expect the dismal prescriptions of clean living: exercise, moderation and a healthy diet. Indeed, such choices may help people exceed average lifespans by up to a decade. But when it comes to the oldest of the old, new research emphasises the biological rather than environmental factors behind longevity, suggesting that distinct genetic characteristics animate most centenarians.

The study by Paola Sebastiani, of the Boston University School of Public Health in Massachusetts, and her colleagues is the largest investigation conducted into the genetics of extreme old age. The team analysed DNA from more than 1,000 people aged between 95 and 119 to look for genetic markers which were not present in those who live an average span.

The study, published in Science, yielded 150 markers correlated with long life. Many sequences were associated with mental alertness, insulin regulation and DNA stability, confirming results from smaller studies and suggesting areas for life-prolonging research.

The researchers also developed a statistical model to forecast longevity. After determining which genetic markers were most strongly associated with lifespan, they applied that knowledge to DNA samples from another set of individuals. Using their model, they were able to identify 77 out of every 100 known centenarians by genetics alone. And carriers of these markers are far likelier—though still unlikely—to reach 100 than those who don't.

There was no single, winning combination of genes unique to healthy ageing. Rather, 19 distinct cohorts emerged, each bearing different combinations of genetic markers—and equally distinct patterns of disease onset and physical decline. This suggests that the cumulative interactions of many genes orchestrate both overall lifespan and patterns of healthy ageing.

Despite this strong genetic evidence, ceding longevity entirely to biology would be premature. Even among the very old Dr Sebastiani found 30 centenarians who possessed almost none of the expected genetic markers. Some had a family history of prodigious old age—a pattern of heritability indicating that the study may have missed rare genetic variants. The rest, however, had no such ancestry. It seems that good luck and healthy living can sometimes overcome a lacklustre pedigree.

Correction: We overstated the power of a genetic test. It is 77% accurate at identifying known centenarians, not predicting whether someone will live past 100. This was corrected on July 6th 2010.