Update: a couple of small corrections inserted
in square brackets below. Thanks to Stephen Coles of UCLA.
My
latest Mind and Matter column in the Wall Street Journal
After celebrating her 60th year on the throne in style this past
week, Britain’s Queen Elizabeth II can now look forward to breaking
some more records. She is already, at 86, Britain’s oldest monarch
(were she to die now, her son would immediately be the 12th
oldest). On Sept. 10, 2015, she would pass Queen Victoria to become
the longest-reigning monarch in British history. To beat Louis XIV
(who succeeded to the throne at the age of 4) for the longest reign
in European history, she would have to live to 98.
Elizabeth II is still going strong, but the maximum human
lifespan isn’t rising at anything like the rate of average life
expectancy, which is rushing upward globally at the rate of about
three months a year, mainly because of progress against premature
mortality. Indeed, we may already have hit some kind of limit for
maximum lifespan-perhaps because natural selection, with its strict
focus on reproductive success, has no particular need to preserve
genes that would keep us going to 150.
The oldest woman in the world, Besse Cooper, a retired
schoolteacher in Georgia, will be 116 on Aug. 26, according to the
Gerontology Research Group, an organization that studies aging
issues. That’s a great age, but it’s a hefty six years short of the
record: 122 years and 164 days, set by Jeanne Calment of France in
1997. In other words, if Mrs. Cooper can get there, Mrs. Calment’s
record will have stood for 21 years; if she can’t, maybe
longer.
That’s a long time, considering that there are now nearly a half
million centenarians alive in the world. That number
has been going up 7% a year, but the number of those over 115
is not increasing.
If Mrs. Cooper does not take the record, there are only two
other 115-year-olds alive to take on the challenge, and one of them
is a man: Jiroemon Kimura, a retired postman from Kyoto. He’s
within seven months of beating the age record for his sex, set by
Christian Mortensen, who died in 1998. But Mr. Kimura is less
likely than a woman to make 122, and there are fewer women
over 115 today (two) than there were in 2006 (four) or even 1997
(three [this should be four]).
At least two people
died after their 110th birthdays in the 1800s, if you’re willing to
trust the birth certificates [No: one of these did not have a birth
certificate]. So the increase of 12 years in maximum life
expectancy during the 20th century was just one-third as large as
the increase in average life expectancy during the period (36
years).
In 2002, James Vaupel of the Max Planck Institute for
Demographic Research in Rostock, Germany, startled
demographers by pointing out that every estimate published of the
level at which average life expectancy would level out has been
broken within a few years. Jay Olshansky of the University of
Illinois, however,
argues that since 1980 this has no longer been true for
already-old people in rich countries like the U.S.: Official
estimates of remaining years of life for a woman aged 65 should be
revised downward.
Thanks to healthier lifestyles, more and more people are
surviving into old age. But that is not incompatible with there
being a sort of expiration date on human lifespan. Most scientists
think the decay of the body by aging is not itself programmed by
genes, but the repair mechanisms that delay decay are. In human
beings, genes that help keep you alive as a parent or even
grandparent have had a selective advantage through helping children
thrive, but ones that keep you alive as a great-grandparent-who
likely doesn’t play much of a role in the well-being and survival
of great-grandchildren-have probably never contributed to
reproductive success.
In other words, there is perhaps no limit to the number of
people who can reach 90 or 100, but getting more than a handful of
people past 120 may never be possible, and 150 is probably
unattainable, absent genetic engineering-even for a monarch.