-----Original Message-----
From: Dawsonzhu@aol.com [mailto:Dawsonzhu@aol.com]
Sent: Wednesday, November 07, 2001 7:59 PM
To: asa@calvin.edu
Subject: Re: Applied evolution
Norm Woodward wrote:
NW: I tried to pick up on the basis of his claim of non-viral causes of
AIDS, but none sprung up on my search engine. I did see his "conspiracy
theorizing," with which I tended to agree. I also have another pet theory,
which is only backed by certain anecdotal evidence, that many deaths due to
AIDS could have been prevented if those who were tested "HIV positive" for
the related antibody were not told that they would inevitably develop
full-blown AIDS. The fact that so many HIV positive individuals have
survived much longer than expected, without developing any AIDS related
symptoms, would indicate to me that their personal immune system had
successfully defended against their initial exposure. However, if the
individual was told that further "risky behavior" would have no effect on
their prognosis, their subsequent exposure to other, perhaps more resistant,
strains could lead to a fatal infection.
In regard to your comments on AIDS, the reason people some
people are resistant to AIDS is due to polymorphism in the
human genome (natural variation in the coding sequences between
different individuals). Some African pygmies who depend on
monkeys as part of their diet and are occasionally exposed to
blood from monkeys infected with the SIV virus (a very close
relative to the HIV virus), are virtually immune to
the AIDS virus. Hence, polymorphism in the CD4 receptor
that the AIDS virus uses to infect the T cells has produced
what is called a "selective advantage" in human populations
regularly exposed to the perils of dietary constraints.
---And if these individuals were tested for HIV, would antibodies show up
indicating they were "infected'? And could exposures to new strains
overcome this "virtual" immunity. (You probably answered these in this
reply, but I am still running to keep up. But I sure would like to be able
to show off my pet theory, if it can do the trick.)
Indeed, here you have an example of where the _host_ evolves
a defense strategy against an infectious agent. It's maybe
not "_applied_", but it sure is predictable. In fact, one of
the places where you see the most adaptation is in the area
of disease, because for most of the history of the human race,
disease was the major threat to our survival. Consequently,
you can find a kind of "regionalism" appearing on the human
genome.
I agree. One of the things I have heard claimed all my life is that today's
people live longer than ever before, that people reaching 50 was considered
old in the days of old. Yet I have not seen historical data that bear this
out.
Certainly high infant mortality rates and epidemics may have brought the
"averages" down, but the robust survivors, due to their natural immune
systems and rugged lifestyles, probably were in better shape in their 70's
than most of us in our 50's.
Whoops...I am sounding like an evolutionist. Disregard the above. 8^)
Also, you still insist that most mutations are harmful.
No, I don't think I have. I just said that just as having two wheels is
more detrimental to a car than a bicycle, a virus has fewer lifestyle
concerns than cellular beings. (I would like to claim permission to change
my mind if I find myself painted into a corner during redirect.)
Maybe
so, but every single day, a person infected with HIV produces
1 billion variants of the HIV virus. The viral genome is about
ten thousand nucleotides long, so there are a lot of places where
a single nucleotide change leads to a negligible effect and there
is a good chance that at least one of them every few days has
a selective advantage. People who think this is only a disease
for gays are only fooling themselves. On a much longer time
scale, we are all at risk.
Well yeah! In fifty years, I'll probably be dead.
Thanks for your response,
Norm
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