Researchers around the world are looking at those who have lived a century or nearly so in efforts to learn what makes them different from those whose lives are shorter. While no single factor has been identified to account for such longevity, most would agree that centenarians have good genes and that they have avoided most toxic stressors, such as tobacco and excessive alcohol.

While a number of genes that shorten life span have been found, identifying the genes that lengthen life span is more difficult. Among the genes found in higher percentages among the oldest old are:

Apolipoprotein E: The E2 variant is more frequent in centenarians while the E4 is half as common as in younger populations (which suggests, but does not prove, that those with the E4 gene die younger, while those with the E2 live longer).²⁶

Angiotensin converting enzyme: This gene plays a role in high blood pressure, and people with a particular version of it have been observed to live longer.²⁷

HLA: The HLA genes relate to various immune functions. Certain variants have been found with greater frequency in centenarians than in younger populations. Some researchers attribute this to better resistance to infection and inflammatory processes.²⁸

Plasminogen activator inhibitor 1: By moderating the actions of some of the proteins in our cells, scientists believe that this gene can reduce the destructive effects of such diseases as atherosclerosis, which would otherwise shorten our life spans.²⁹

Dr. Thomas Perls of Harvard Medical School and the Director of the New England Centenarian Study and his colleagues have been studying centenarians in the Boston area for several years. They have identified some lifestyle and personality factors that seem to contribute to longevity, but they have also found that there are about as many lifestyle and personality differences as there are similarities.

Dr. Perls and his colleagues have identified several families with many long-lived members. This supports the argument that at least some of longevity is indeed in the genes.³⁰ Interestingly, two of those families have origins in the same area of Norway. This confirms what other researchers have noted that some gene or genes present in high numbers in such isolated populations may contribute to longevity.^31,32

Dr. Perls and his colleagues have also designed a quiz called the Living to 100 Life Expectancy Calculator© (see Weblinks). It asks a series of questions about lifestyle and family history and current age and then calculates your predicted life span based on what is known about centenarians and avoiding unnecessary risks that would shorten lives. The quiz is based on findings that while healthy behaviors and lifestyle can help most of us live into our 80's, good genes are probably what allow centenarians to avoid the age-related diseases and conditions that kill most of us.