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Who Are Centenarians?
(pg. 1)
Written By Thomas T. Perls MD, MPH, FACP
Harvard Division on Aging, Beth Israel Deaconess Medical Center
Centenarians are the fastest growing segment of our population.
The second fastest is the age group 85+.
Currently, there are probably about 50,000 centenarians
in the United States, or a little more than 1 centenarian
per 10,000 in the population (the above estimate may be a
relatively small over-estimation); 90% of them are women,
10% are men. This prevalence rate is approximately the same,
or a little higher than other industrialized countries.
Why?
The age composition of the population is changing dramatically.
More and more people are now able to achieve their individual
life expectancy potentials. This is a dramatic change from
the turn of the century, when many people died prematurely
especially in infancy. In fact, at the turn of the century,
when our centenarians were young children, the population,
in terms of age, was in the shape of a steep triangle, with
the vast proportion being young and only a very few reaching
very old age. At that time, 1 in 100,000 could expect to go
on to be 100 years old. Now, the picture is very different.
We are experiencing a rectangularization of the population;
more and more people are living beyond the vulnerable childhood
years and achieving old age, so that the older group at the
top ages nearly equals the bottom.
A tremendous force in the population will drive the unprecedented
growth of the 65+ population in the early part of the next
century -the baby boomers. The first baby boomers recently
turned 50 years old. Actually, this 70 million-strong group
now constitutes the "elder boomer" generation! By the first
decade of the next century, there will be as many seniors
as there are people under the age of 20. Approximately 3 million
of these elder boomers can expect to become centenarians.
An important component of the elder boomers' disproportionate
ability to achieve extreme age is their relatively high level
of education, income and attention to good health habits.
Are Centenarians a New Phenomenon?
Prior to the 20th century, average life expectancy was about
45 years of age. However, one must distinguish between average
life expectancy and life span. Average life expectancy is
the average age members of the population survive to. Life
span is the maximum age obtainable for the species and is
defined by the age of the oldest living individual. In the
case of humans, that individual was Madame Jeanne Calment
who died at the age of 122 years in August, 1997. Madame Calment
therefore had a tremendous responsibility ... in her later
years, every day she lived, she extended the human life span
by a day.
Prior to the twentieth century, though life expectancy was
half of what it is today, life span was probably not that
different. There are numerous instances of people living well
into their nineties reported as far back as the sixteenth
century. Titian, the well known Italian master painter, lived
to at least age 90 and may have been as old as 99 years of
age. Hippocrates reportedly died in his mid eighties. To say
that life span also doubled in even the last thousand years
would be hard to substantiate, especially from an evolutionary
point of view. For example, what genetic changes could possibly
occur over the course of a thousand years that would provide
such an enormous survival advantage?
Centenarians continued
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