JEANNE
CALMENT (pictured), who lived for 122 years and 164 days (longer than
any other person), said the secret to her longevity was a diet rich
in olive oil, port wine and chocolate. She smoked until the age of
117. Alexander Imich, who was the oldest living man (111) until he
died in June, did not have a secret. Asked how he lived so long, he
replied, "I don’t know, I simply didn’t die earlier."
Scientists are looking for more plausible and definitive reasons why
some people live much longer than others. Many think the genes of
centenarians like Calment and Imich hold the key.
And some believe
that their research might one day provide a positive answer to the
question that has fascinated man since at least the time of
Herodotus: is it possible for humans to live for ever?There
are a number of biological components involved in the process of
ageing. These cause the body to slowly degrade at the cellular level.
Old age is also a leading risk factor for many common illnesses, such
as cancer and heart disease. Tackling ageing, therefore, is seen as a
way to combat many diseases at once. This is the motivation behind
Google's anti-ageing startup called Calico, which was founded last
year and is led by Art Levinson, the former head of Genentech, a
pioneer of the biotechnology industry.
Craig Venter, a geneticist who
was instrumental in the sequencing of the human genome, created a
similar company earlier this year. The primary goal of these and
other efforts is not necessarily to extend humans' lifespan, but
rather their healthspan, or the number of years lived in good health.
Many scientists, though, believe that any effort to slow or stop the
progression of age-related diseases must deal with the cellular
damage involved in ageing—so longer life is an inevitable and
welcome byproduct.These newer outfits and much anti-ageing research
over the past decade have focused on genes. The chances of a person
living to 80 are based mostly on behaviour—don't smoke, eat well
and exercise—but the chances of living beyond that are based
largely on genetics. So scientists are looking for the "protective
genes" that slow cellular decline and ward off diseases in
people like Calment and Imich.
If researchers can find them it is
hoped that pharmaceutical firms might create drugs that mimic their
effects in people otherwise likely to achieve normal lifespans. That
might only get them to Calment's age, which some scientists believe
is the absolute limit of human longevity. Others think that to go
further the body must be treated like a machine in need of regular
repair and replacement parts. Regenerative medicine offers some hope
in this regard. Scientists are using stem cells to grow human
replacement parts, like tissues and organs. In theory, a person could
keep going back to the shop for new parts, so long as his brain
remained intact. Scientists even talk about treating diseases that
ravage the brain, like Alzheimer's and Parkinson's, with replacement
nerve cells.Optimists, like Aubrey de Grey, a provocative anti-ageing
researcher in England, believe that technology will allow people
alive today to live well beyond Calmet's 122 years. Most others
believe that such progress is some way off. A more realistic hope is
that anti-ageing research will lead to lower health-care costs.
One
of the characteristics of the very old is that they tend to be
healthy right up until their deaths. They therefore cost health-care
systems less than most old people, especially those suffering from
chronic diseases. Scientists talk of a "longevity dividend"
that might be achieved by compressing the period of ill health at the
end of life for everyone. This would at least address the paradox of
the quest for eternal life: people want to live for ever, but they
don't want to grow old.
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