Extending Human Life: Progress and Promises
By
Ker
Than
LiveScience Staff Writer
Recent experiments on everything from roundworms
to mice are giving some scientists hope that our
maximum life spans are not set in stone but can
be extended far beyond what nature intended.
In many ways, tremendous progress has already
been made in extending human life. From lowering
infant mortality rates ( the
biggest factor ) to creating effective
vaccines and reducing deaths related to heart
problems, science has helped increase the average
person's life span by nearly three
decades over the past century.
But getting the average person from 80 to 120
and beyond requires research into the very cellular
mechanisms that cause
gray hair and wrinkles,
that make our bones
creak and our minds
go weak, and what generally make all
creatures shrivel, shrink and waste
away.
The big question: Can cell
aging be halted
or reversed
Eat
less
The first hint of the possibilities came in the
1930's, when studies by Cornell University researchers
discovered that rats fed severely reduced calories
tended to live up to 40 percent longer than their
fully fed littermates.
Scientists still aren't sure how caloric restriction,
or CR, works. One early hypothesis, that CR regimens
extended life span by preventing animals from
reaching full body size, was debunked when experiments
showed that even fully grown adults can benefit
from CR.
For about 50 years, CR was the only proven method
to extend an organism's maximum life span in a
healthy way.
Then in 1996, scientists discovered a type of
mutant dwarf mouse that lived up to 70 percent
longer than its non-mutated peers. The rodents'
stunted growth was due to a change at the genetic
level that reduced production of hormones related
to growth.
Genetic tinkering In the years since, genetic
tinkering has also produced more enduring
yeasts, roundworms and fruit flies.
Much
of the anti-aging research is still done on rodents,
whose biological systems are similar to humans
in many ways. In fact, a leading proponent of
human anti-aging research has organized a hefty
prize for breakthroughs that extend
the lives of mice.
Scientists have also discovered other factors
that affect life span in research that might eventually
be applied to humans. A study out of Cambridge
University in England found that what a mother
eats during pregnancy and while nursing
can greatly affect her children's life spans.
Using mice, the researchers found that mothers
fed protein-rich diets during pregnancy, but low-protein
diets while breast-feeding, had pups that lived
up to 50 percent longer than those for whom this
feeding pattern was reversed. If a similar approach
could work for humans, this translates into a
difference between reaching 50 and living to be
75 years old, the researchers said.
Get
married
If the thought of eating only enough to survive
or having your genes mucked with doesn't sound
very appealing, scientists say there is another
and perhaps more pleasurable way to live longer:
fall in love.
A study earlier this year led by Linda Waite,
a sociologist at the University of Chicago, showed
that happily
married couples tend to live longer
than unwed individuals. Married men were found
to live, on average, 10 years longer than non-married
men, and married women lived about four years
longer than non-married woman.
The researchers speculated that married men live
longer because they adopt healthier lifestyles
and take fewer risks. Married woman, on the other
hand, probably live longer because of the improved
financial well-being that comes with marriage.
* SPECIAL
REPORT: Toward Immortality
* Scientists
Discover Healing Power of Bones
* Potentially
Harmful 'Undead Cells' Collect with Age
* Roots
of Graying Hair Discovered
* Churchgoers
Live Longer
* Optimists
Live Longer
* The
Odds of Dying