It's an age-old joke, or perhaps an old-age joke, that when asked the question, “Who wants to live to be 100?”, the answer is “anyone who is 99!”

In my family we celebrated two 90th birthdays over the past two months. Friends have asked me if I am lucky enough to have the good genes. I could only smile and hope. This week however, research from the New England Centenarian Study (NECS) published in Science, revealed that there are in fact 19 genetic clusters of extreme longevity (EL). Perhaps soon I will be able to answer the question.

Another joke poses the question, “how old do you have to be to die of old age?” While this may seem like a silly question, there is a biological answer. It seems that for an altricial* species to be successful, the parents must live long enough to raise their young. If human female fecundity is in the age range of 40 to 45 years, then a parent would need to live to at least 60 to ensure the last child is reared successfully. Is it possible that the social structure of early humans also incorporated grandparents as part of successfully raising the children? If this is the case, selection pressure could favour an upper age in the mid-70s. Interestingly, the NECS indicated that the average age for their control group, i.e., those not deemed to be long-lived individuals, is 73. The EL genetic clusters were found in a population described by study authors Paola Sebastiani and Thomas Perls as centenarians and super-centenarians. They lived significantly longer, to at least 95 years and up to an extreme of 119 years at death.

An impressive application of mathematics and statistics was used to ensure controls and statistical significance to the study. At least 50,000 data points were simulated and compared to actual results. Studies ensured that stratification and overlap of controls as well as gender did not play any role. Through Genome Wide Association Studies (GWAS), they identified 231 SNPs associated with a variety of diseases. They found that on average, both the centenarians and the control group carry an average of 35% of the risk alleles. The indication is that it is the rate of aging, and/or the age of onset of the diseases that make the difference expressed in those persons with the EL genetic clusters.

The study identifying genetic markers associated with longevity has not yet determined the genes implicated. The follow-up research will need to determine the genes involved and what they do to contribute to reaching long life. Genetic clusters or not, we still need to pursue a healthy lifestyle to live long and prosper.

* altricial species are those that are born relatively helpless and require rearing by their parents, as opposed to precocial species that are born relatively mature and independent.