On
Aug. 4, 1997, Jeanne Calment passed away in a nursing home in France.
The Reaper comes for us all, of course, but he was in no hurry for Mrs.
Calment. She died at age 122, setting a record for human longevity.
Jan
Vijg doubts we will see the likes of her again. True, people have been
living to greater ages over the past few decades. But now, he says, we
have reached the upper limit of human longevity.
“It
seems highly likely we have reached our ceiling,” said Dr. Vijg, an
expert on aging at Albert Einstein College of Medicine. “From now on,
this is it. Humans will never get older than 115.”
Dr. Vijg and his graduate students Xiao Dong and Brandon Milholland published the evidence for this pessimistic prediction
on Wednesday in the journal Nature. It’s the latest volley in a
long-running debate among scientists about whether there’s a natural
barrier to the human life span.
Continue reading the main story
Leading figures in the debate greeted the new study with strong — and opposing — reactions.
“It
all tells a very compelling story that there’s some sort of limit,”
said S. Jay Olshansky, a professor of public health at the University of
Illinois at Chicago, who has made a similar argument for over 25 years.
James
W. Vaupel, the director of the Max-Planck Odense Center on the
Biodemography of Aging, has long rejected the suggestion that humans are
approaching a life span limit. He called the new study a travesty.
“It is disheartening how many times the same mistake can be made in science and published in respectable journals,” he said.
Dr. Vaupel bases his optimism on the trends in survival since 1900.
A
child born in the United States in 1900 had an average life expectancy
just short of 50 years. An American child born today can expect to live
on average to age 79. Japan’s average life expectancy at birth has risen
the furthest of any country so far, to 83 years.
But when Dr. Vijg and his students looked closely at the data on survival and mortality, they saw something different.
The
scientists charted how many people of varying ages were alive in a
given year. Then they compared the figures from year to year, in order
to calculate how fast the population grew at each age.
The
fastest-growing portion of society has been old people, Dr. Vijg found.
In France in the 1920s, for example, the fast-growing group of women
was the 85-year-olds.
As
average life expectancy lengthened, this peak shifted as well. By the
1990s, the fast-growing group of Frenchwomen was the 102-year-olds. If
that trend had continued, the fastest-growing group today might well be
the 110-year-olds.
Instead,
the increases slowed down and appear to have stopped. When Dr. Vijg and
his students looked at data from 40 countries, they found the same
overall trend.
The
shift toward growth in ever-older populations started slowing in the
1980s; about a decade ago, it stalled. This might have occurred, Dr.
Vijg and his colleagues said, because humans finally have hit an upper
limit to their longevity.
To
further test this possibility, the researchers analyzed the
International Database on Longevity, assembled by Dr. Vaupel and his
colleagues. It contains detailed reports on 534 people who have lived to
extremely old age.
Dr.
Vijg and his colleagues combed through the data, noting the year that
each person in the database died, and charted the greatest age that
someone had reached in each year since the 1960s.
In
1968, the oldest age attained was 111. By the 1990s, that figure had
increased to around 115. But then this trend stopped, too. With rare
exceptions like Jeanne Calment, no one has lived beyond 115 years.
The
stall is evident not just among the longest-lived. “When you look at
the second-oldest person — and the third and the fourth and the fifth —
the trend is always the same,” said Dr. Vijg.
On
the researchers’ graph, Jeanne Calment is “clearly an outlier,” said
Dr. Vijg. He and his students also calculated how likely it would be for
someone to live much past her, given current trends. The verdict:
practically nil.
“You’d need 10,000 worlds like ours to have the chance that there would be one human who would become 125 years,” said Dr. Vijg.
Given
the data, the scientists predict the future will look a lot like the
present. “We expect that the oldest person alive will be around 115
years for the foreseeable future,” said Brandon Milholland, who worked
with Dr. Vijg on the study.
Scientists
have long debated whether there’s a limit to life span — not just for
humans, but for any species. Only now, thanks to the long increase in
average life expectancy, are people living long enough to hit the
ceiling, Dr. Vijg said.
But
Dr. Vaupel points out that in some countries, such as Japan, the cohort
enjoying the fastest growth is continuing to shift older. As for the
world records for life span, Dr. Vaupel argued that Dr. Vijg had failed
to use the most powerful statistical methods available to analyze the
data.
On
the other hand, Leonard P. Guarente, a professor of biology at M.I.T.,
praised the new study, saying it confirms an intuition he has developed
over decades of research on aging.
“This
paper is a good dose of medicine, if you’ll pardon the expression, for
those who would say there is no limit to human life span,” Dr. Guarente
said.
Starting
in the late 19th century, average life expectancy started to rise
because fewer children were dying. In recent decades, adults have also
enjoyed better health.
Some
of those improvements have come from quitting smoking and eating better
diets. Antibiotics and drugs for chronic disorders like heart disease
have also helped. But all of the improvements of modern life, Dr.
Guarente and others argue, have not turned back the underlying
biological process of aging.
Based
on his own experimental research, Dr. Vijg describes aging as the
accumulation of damage to DNA and other molecules. Our bodies can slow
the process by repairing some of this damage. But in the end it’s too
much to fix.
“At some point everything goes wrong, and you collapse,” said Dr. Vijg.
The
best hope for our species is not to extend our life spans, Dr. Vijg
argues, but to lengthen our years of healthy living — with healthy
habits and perhaps drugs that can repair some of the cellular damage
that comes with time.
“There’s a good chance to improve health span — that’s the most important thing,” said Dr. Vijg.
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