From: Ramez Naam (mez@apexnano.com)
Date: Tue Jun 17 2003 - 08:18:52 MDT
From: Robert J. Bradbury [mailto:bradbury@aeiveos.com]
> But we know that there are people who can live past 90
> without dying of heart disease or cancer -- so one has to
> assign a significant part of the responsibility to
> self-inflicted causes (smoking, poor diet, etc.) and probably
> an even larger fraction to genetic defects.
Smoking and poor diet merely hasten death. Aging (unless halted)
makes death inevitable.
In fact, most people who die in their 80s or later have multiple
terminal conditions (though they may not realize it). If you cure
one, a different one will get them just a few years later.
Indeed, up until age 100 or so our total risk of death from any cause
rises year after year. Between the ages of 30 and 80 this is an
exponential increase, with the risk of death from any cause doubling
every 7-8 years. Aging causes a systemic loss of our defenses against
illness and death.
> There are just
> too many people who don't get heart disease or cancer to
> place the blame on "aging" per se.
To a first approximation, young people don't get heart disease or
cancer, and old people don't die of anything but heart disease or
cancer.
> "Aging" may be a
> contributing factor but I suspect poor genetic combinations
> are a big part of the problem as well. Does one call
> mutations in the FAP or HNPCC genes that predispose one to
> colon cancer or the several mutations that predispose one to
> Alzheimer's disease "aging"? I would argue no. Yes those
> people age -- but the "cause of death" should be assigned to
> having a losing ticket in the genetic lottery.
Yet 25 year olds don't often die of cancers. The risk of cancer
increases exponentially with age. Nor does this seem to be merely a
factor of the passage of time - Animals that have their aging process
slowed through genetic manipulations also have their cancer risk
shifted to later in life, even though the genes being manipulated are
not themselves oncogenes.
So it's not just about these cancer-associated alleles. It's also
about the increased vulnerability to cancer that old age brings.
cheers,
mez
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