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A Look at Centenarians…
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There are several geographical areas that have claimed inhabitants with extreme longevity, but after closer examination, these claims have been found to be false. Vilacamba, Ecuador almost became a tourist attraction because natives claimed their water was a fountain of youth leading to the many super-centenarians (age >110 years) in that region. What about the reports of people in the Russian Caucases living to 150 years and beyond? Remember the Dannon yogurt commercials? In fact, those purported super-centenarians were taking on the identities of their parents, aunts and uncles. Again, the oldest person from whom we have multiple forms of proof-of-age is Madame Calment.
These regions of purported exceptional longevity still merit careful study however. Though claims of extreme age are untrue, there still may be an unusually high prevalence of very old fit people in these regions. In the Tibetan mountains for instance, octogenarian and nonagenarian elders, impressively many of them men, still herd live stock and still lead physically strenuous lives.
Common Characteristics
The New England Centenarian Study conducted a population-based study in order to find all the centenarians within a given geographic area. The most important finding has been that nearly all of the subjects were independently functioning at least to the age of ninety. This finding is consistent with the hypotheses that these subjects have a history of aging slowly and either avoid or at least, markedly delay disability associated with aging. While about 43% of the centenarians have a history of an age-related illness developing prior to the age of 80 years, and 42% did so after the age of 80 years, approximately 15% have no age-related illnesses at age 100 except for perhaps arthritis or vision and/or hearing problems. It is interesting that despite some of them having at least one illness for a long period of time, they are still able to live the vast majority of their very long lives independently.
Geographic Clustering?
Though reports of people age 130 years and older are unfounded, there may be truth to regions with unusually high prevalence rates. For example, in North America, there may be a “centenarian belt” extending from Minnesota to Nova Scotia. Nova Scotia for example has twice the prevalence rate of centenarians (one per 5,000 people) compared with New England. Such clustering could be due to a founder effect. That is, many of these centenarians could come from ethnic backgrounds (e.g. Celtic, French/Acadian, Scottish) that predispose them to extreme longevity. This hypothesis is based upon the supposition that extreme old age does in fact run in families.
Familial Clustering for Extreme Longevity
In gathering pairs of siblings as part of our Centenarian Study, we identified four families that clearly demonstrate clustering. For example, one family had five out of nine siblings live to at least 100 years.
The probability of observing such clustering just by chance would be fewer than one per all the families that exist in the world today. Thus, for such families to exist, these individuals must have some factors in common that facilitate their survival to exceptional old age.
