From: Kevin Freels (megaquark@hotmail.com)
Date: Wed Sep 03 2003 - 16:16:45 MDT
If the majority of cancers occur in individuals after the age of
reproduction, there would be no filter to remove them.
In fact, any genetic mutation that caused any type of problem after the
reproductive years should persist through the years. This would leave most
people today with a variety of mutations that continue to be passed on to
their offspring. They would continue to persist over hundreds of millions of
years with no selection pressure applied whatsoever.
I wouldn;t think that this would be quality control, or serve any purpose.
It's simply a bunch of bad mutations that have spread throughout the
population simply because they don't affect the ability to reproduce.
This would also be why younger people have far fewer incidences of cancer.
Those cancers would be filtered more by selection pressures.
I know there are ways that scientists have been able to date mutations such
as in the Y chromosome and mitochondrial DNA. I wonder if these mutations
could be dated as well. If so, upon examination we should find that the
childhood cancers are much younger mutations than the cancers that affect
the elderly.Natural selection may have already been reducing these, but not
eliminating since some of the children are still going to survive to the
point where they could reproduce. Any increases today in childhood cancers
would only be because of our medical ability to help these children with
these mutatins survive and reproduce, thereby spreading the mutation further
than it would have "naturally"
----- Original Message -----
From: "Extropian Agroforestry Ventures Inc." <megao@sasktel.net>
To: <extropians@extropy.org>
Sent: Tuesday, September 02, 2003 9:27 PM
Subject: Re: Life's Lethal Quality Control?
> Not a science based answer, the KISS answer ;
> Cell lines can either differentiate and die by apoptosis or attempt to
regenerate
> back to a stem cell line. Cancer might be thought of as an unsuccessful
attempt
> at regeneneration?
>
> "Terry W. Colvin" wrote:
>
> > Science Frontiers, No. 149, Sep-Oct, 2003, p. 2
> > < http://www.science-frontiers.com >
> >
> > BIOLOGY
> >
> > Life's Lethal Quality Control?
> >
> > Cancer is such a deadly scourge of life that one wonders why it was not
> > strongly selected against and totally eliminated from all forms of life
> > long ago. Does cancer's eons-long persistence among a wide spectrum of
> > living things imply that it has some purpose---some positive value that
> > we are blind to?
> >
> > In SF#30, back in 1983, it was observed that the incidence of cancer is
> > strongly correlated with the complexity of organisms. It would seem
> > therefore that cancer tends to damp out any tendency life has (or is
> > given) to attain higher states of diversity and complexity. Some even
> > hold that cancer is the price that must be paid by higher forms of life!
> >
> > But there is much more to be said about the potential roles of cancer in
> > the development of human life.
> >
> > It must be recognized that the bulk of human cancers occur in
individuals
> > beyond the age of reproduction. If old-age cancer has an evolutionary
> > purpose, it might be simply the reduction of the drain nonproducing
oldsters
> > place upon society.
> >
> > One can also speculate as do A. Leroi and J. Graham that cancer is one
of
> > evolution' methods of quality control. To be effective in this role,
> > cancer must affect individuals capable of reproduction---before they
> > reproduce. However, there are only a few lethal childhood cancers
> > specifically associated with additions to human biological diversity.
Two
> > such examples are: brain cancer and bone cancer.
> >
> > These are interesting observations, but they alone can hardly account
for
> > the strong correlation between cancer incidence and complexity.
> >
> > J. Graham goes much further in his 1992 book _Cancer Selection_. There,
he
> > claims that cancer is *the* driving force in the creation of biological
> > diversity. In other words, living things tend to evolve features that
> > reduce the incidence of cancer. One of the examples Graham proposes is
> > the evolution of shells by snails to protect themselves from
cancer-inducing
> > solar ultraviolet light. His book contains many more examples.
> >
> > (Watts, Geoff; "Life's Lethal Quality Control," *The Times Higher
Education
> > Supplement*, April 11, 2003. Cr. J. Graham.)
> >
> > Comment. Since cancer has survived the filtering action of natural
> > selection for hundreds of millions of years and attacks so many organs
> > in so many diverse species, we wonder if it has a single, simplistic
> > explanation.
> >
> > --
> > "Only a zit on the wart on the heinie of progress." Copyright 1992,
Frank Rice
> >
> > Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1@mindspring.com >
> > Alternate: < fortean1@msn.com >
> > Home Page: < http://www.geocities.com/Area51/Stargate/8958/index.html >
> > Sites: * Fortean Times * Mystic's Haven * TLCB *
> > U.S. Message Text Formatting (USMTF) Program
> > ------------
> > Member: Thailand-Laos-Cambodia Brotherhood (TLCB) Mailing List
> > TLCB Web Site: < http://www.tlc-brotherhood.org >[Vietnam veterans,
> > Allies, CIA/NSA, and "steenkeen" contractors are welcome.]
>
>
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