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Expert
Tinkers With Evolution
to Create Human "Built-To-Last"
If
humans were designed to live beyond age 100 and remain free of
many of the diseases and disorders associated with aging, we might
have looked like short, stout elves. This conclusion may be drawn
from illustrations that accompany the article, “If Humans
Were Built to Last,” by UIC Professor S. Jay Olshansky and
his colleagues in the March 2001 issue of the magazine Scientific
American.
Our bodies evolved
to survive long enough to reproduce and raise our young, says
Olshansky, professor of biostatistics in the UIC School of Public
Health and noted demographer of aging. Human ingenuity has made
it possible for us to extend our lives well past our reproductive
years.
“Had our
bodies been crafted for extended operation, we would have fewer
flaws capable of making us miserable in our later days,”
he writes. “Evolution does not work that way. Instead, it
cobbles together new features by tinkering with existing ones
in a way that would have made Rube Goldberg proud.”
The article, written
with Bruce Carnes, senior research scientist at the National Opinion
Research Center at the University of Chicago, and Dr. Robert Butler,
president of the International Longevity Center in New York City,
outlines design “flaws” that lead to bodily malfunctions
as we age, and the hypothetical, evolutionary design “fixes”
that would allow us to enjoy good health well into our postreproductive
years.
“Humans
can live for a long period of time in good health because the
harsh environments of our ancestors forged a human-body design
that is robust,” said Carnes. “But the seeds of self-destruction
sown at conception become more obvious with the passage of time.”
The article includes
illustrations of what humans might look like if we were designed
for health and longevity. For example, some of the extended-use
features might include rewired eyes, bigger ears that are mobile,
a curved neck, forward-tilting upper torso, extra-padded joints,
larger bones and muscles, shorter limbs and stature and backward-bending
knees.
Walking upright
probably contributed to human intelligence and an expanded foraging
range, the authors note, but at the price of aging-related disorders,
including slipped disks, lower back pain, varicose veins and worn-out
joints.
Where our heads
are concerned, the authors cite the weak link between the optic
nerve and retina, which is prone to detaching after decades of
use, fragile hair cells in our ears leading to hearing loss, and
a common passageway for food and air, raising the risk of inhaling
food or drink as muscle tone decreases with age.
Then, there are
what the authors refer to as “plumbing problems.”
In males, these problems include a urethra prone to constriction
by an enlarged prostate that may obstruct the flow of urine, and
in females, bladder and pelvic-floor muscles and ligaments that
weaken with time and multiple pregnancies, which may lead to incontinence.
Emphasizing the
positive message of the article, Butler observes, “Despite
the limitations and flaws about which we write, there is so much
power we as individuals have to maintain our health. Through good
health habits and modern medical interventions, we have an opportunity
to, as the Greek lyric poet Pindar said, exhaust the limits of
the possible.”
Olshansky and
his colleagues contributed to the development of a paradigm for
understanding mortality known as biodemography. This approach
to human aging and longevity, as well as age patterns of death
across species draws on the disciplines of demography, epidemiology,
evolutionary biology, molecular biology and anthropology.
Olshansky is the
author with Carnes of the new book, “The Quest for Immortality:
Science at the Frontiers of Aging,” published by Norton.
Reference
Source 99
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