“The Yarmouth area would have been settled by only 20 or 30 families,” MacKnight says. “Many of the people who live there now are their descendants.” The question is, he says, did one of the original ancestors bring a gene or genes that predisposed them to extreme longevity, which have been passed down through the generations?
In Boston, Perls and his colleagues, who have been studying centenarianism for almost a decade, gathered promising evidence to support the notion of a genetic basis for extreme longevity: a woman with a centenarian sibling is at least eight times more likely to live 100 years than a woman without such a sibling; likewise, a man with a centenarian sibling is 17 times more likely to reach 100 than a man without one. “Without the appropriate genetic variations, I think it’s extremely difficult to get to 100,” Perls says. “Taking better care of yourself might add a decade, but what matters is what you’re packin’ in your chassis.”
Additional evidence comes from recent studies on DNA. Drs. Louis M. Kunkel and Annibale A. Puca of Children’s Hospital in Boston—molecular geneticists working with Perls— examined DNA from 137 sets of centenarian siblings. Human beings have 23 pairs of chromosomes (the spindly structures holding DNA strands), and the researchers discovered that many of the centenarians had similarities in their DNA along the same stretch of chromosome No. 4. To Perls and colleagues, that suggested that a gene or group of genes located there contributed to the centenarians’ longevity. The researchers are so determined to find one or more such genes that they formed a biotechnology company in 2001 to track them down: Centagenetix, in Cambridge, Massachusetts.
Scientists suspect there may be a handful of age-defying genes, and the competition to pinpoint and understand them is heated. Medical researchers and drug company scientists reason that if they can figure out exactly what those genes do, they may be able to develop drugs or other treatments to enhance or mimic their action. To skeptics, that might sound like the same old futile quest for a fountain of youth. But proponents of the research are buoyed by a little-appreciated fact of life for many of the super old: they’re healthier than you might think.
That, too, has been borne out in Nova Scotia. “I’m forgetful, I can’t help it,” says 96-year-old Doris Smith of Lunenburg. “But I’ve never had an ache nor a pain.”