Although previous studies had already demonstrated a strong familial component to longevity, new research based on the largest group of long-lived families yet studied offers additional insight into why this might occur. Researchers writing in the Proceedings of the National Academy of Sciences report today that siblings of centenarians are 50 percent less likely to die at any given age than are members of the general population. This lifelong advantage over the rest of the populace leads to far longer and healthier lives for brothers and sisters of long-lived people.

By examining 444 families with at least one centenarian, Thomas Perls of the New England Centenarian Study and his colleagues analyzed data on the health and age of death of the siblings of long-lived people. The team found that not only do these siblings enjoy a significantly lower death rate, but their average age of death was almost 17 years older than that of the general population. In addition, brothers of 100-year-olds were 17 times as likely as people without centenarian siblings to reach the age of 100, and sisters had an eight-fold advantage.

The researchers posit that this difference is mostly a result of a family's shared beneficial genetic makeup, not similar environmental circumstances--siblings' strong proclivities to old age are nearly equal across income, race and sociodemographic classifications and seem dependent only on the familial connection. Other studies have attributed such profound differences in longevity to a significantly smaller genetic likelihood of developing and dying from age-related diseases such as Alzheimers disease, cardiovascular ailments and cancer. "[These findings] provide further evidence that centenarians and their relatives are a special group in that they appear to be more resistant to disease or they survive disease better throughout their life span," notes Evan C. Hadley of the National Institute on Agings Geriatrics and Clinical Gerontology department. "This survival advantage is likely due to genetics and environmental factors, but the roles of each of these factors is unclear. Studying these individuals could help us understand the factors that contribute to long, healthy lives."