There is a substantial distinction to be made
between the genetics of aging and the genetics
of exceptional longevity. Twin studies suggest
that the average set of genetic variations
facilitate the average human's ability to live
well into their octogenarian years. Other
studies indicate that taking full advantage of
this average set results in spending the
majority of those years in good health.
However many people counteract such genetic
endowment with poor health habits resulting
in a substantially lower average life expectancy
and relatively more time spent in poor health.
To live beyond the octogenarian years, life
span experiments in lower organisms and
mammals and population and molecular
genetic studies of centenarian sibships indicate

 

that genetic factors play an increasingly
important role as the limit of life span is
approached. These factors are likely to
influence basic mechanisms of aging, which in
turn broadly influence susceptibility to agerelated
illnesses. Lacking genetic variations that
predispose to disease as well as having
variations that confer disease resistance
(longevity enabling genes) are probably both
important to such a remarkable survival
advantage. The rapid rise in the incidence of
centenarians could indicate that many more
people than we originally thought have the
optimal set of genetic factors necessary to get
to 100 and beyond. Recent studies indicate the
likelihood that such factors will be elucidated
in the near future.