Caloric restriction slows brain aging

mikalra at my-deja.com mikalra at my-deja.com
Sun Jul 2 10:10:04 EST 2000


In article <r87uls0p6gglmn3j3rdlqa6n186ift89oo at aol.com>,
  tateg at keydatatech.com wrote:
> On Sun, 02 Jul 2000 00:39:33 GMT, mikalra at my-deja.com wrote:
>
> >Yes :). Analysis with evolutionary theory demonstrates that "planned
> >obsolescence" genes will always be powerfully selected AGAINST, because
> >of the nature of natural selection. Such genes yield benefits to all
> >competing organisms, but only accrue costs to those bearing them;
> >organisms not bearing such genes will thus leave more young behind in the
> >spaces left by the "altruistic," and the whole scheme will fall apart at
> >the hands of the "tragedy of the commons." For an excellent, highly
> >readable discussion of the point, see _Why We Age: What Science Is
> >Discovering about the Body's Journey Through Life_ by Steven N. Austad.
> >Paperback - 256 pages 1 edition (March 11, 1999)  John Wiley & Sons;
> >ISBN: 0471296465.
> >
> >-Michael
>
> An excellent point, and it sounds very reasonable. But even so there
> are obvious signs that built in obsolescence is at work at least to
> some extent. At least they seem obvious to me. If nothing else
> consider menopause in women. After she has had her chance to have
> children her body just kind of says to heck with it and starts it's
> inevitable decline. It's nature's way of discarding what is no longer
> useful after it has served it's purpose.

It seems that way; that's why programmed obsolescence (or "built in self
destruct" -- same thing) theories have found so many adherents outside of
evolutionary theorists per se. But menopause is not a programmed
destruction. The evils of the pause come from endocrine disruptions
arising from the fact that the hormone feedback loops are all dependent
on ova-releasing ovaries. when the ovaries run out of eggs, FSH & LH go
NUTS trying to stimulate ovulation, which suppresses estrogen &
progesterone (if I have this slightly off, anyone, feel free to correct
me, but this is the basic picture).

"But," you say, "doesn't this mean that the lack of eggs is a clock?" In
a sense, yes -- but the organism wasn't built with a limited supply of
eggs to kill it off: again, this would be counterproductive. rather, the
organism is built with enough eggs to ensure that it will have enough to
last its natural life. Emphasis on "natural." remember, until this
century, nearly all cultures had an av'g age of death of <25, and even
welthier nations were under 40. Designing an organism with all the
preservation resources and supplies (such as ova) to last indefinitely is
a waste of resources if the organism is almost sure to die of malaria,
accidents, predation, or warfare long before. Those resources are instead
spent making the organism maximally reproductively fit for its extrinsic
LS. IOW, Nature doesn't design us to die ("you've served your purpose,
but now you're a drain and must go") -- it just doesn't build us to last
forever.

-Michael


Sent via Deja.com http://www.deja.com/
Before you buy.







More information about the Ageing mailing list