Date: Tue, 09 Apr 1996 19:15:59 -0600
Subject:  old age, etc, reply to Adam


>>> Adam Rose <adam-AT-pmel.com>  4/9/96, 03:12am >>>
It seems to me that if you look at the survival of both men and women
into old age from the point of view of the group as a whole, a number
of possibilities arise which might explain why humans society evolved
as it did.

LR:  Sure.  But why would people evolve to have longer lifespans?

AR: (b) Resolving social conflict within the group ie acting as
referree I would guess, particularly in times of reduced resources,
that real tensions could develop within the group. At times like
this, some commonly respected referee could be important in holding
the group together. This could be very important if there was some
optimum size below which a group becomes more prone to temporary
fluctautions in its fortunes.

LR:  When food is scarce, being in a large group _could_ be the worst
thing for you.  Anything you reach out to pick, there is everybody
else grabbing for the same thing.  Again, it depends on the specific
features of the local environment.  If there are only a few permanent
waterholes during the dry season, people are forced to flock together
in large groups, but then they eat up everything nearby and have to
hike farther to get food every day [Kalahari].  An individual does
not have to stay in the group or "respect" anybody unless hse wants
to, and hir behavior I expect to respond to opportunities, costs and
benefits that ultimately may affect survival and reproduction.

AR: (c) A Reserve Army of Labour ?
The old can still work, if not at the rate of younger adults.

LR:  There is no evolutionary reason for anyone to live beyond the
point where hse is contributing to hir _own_ fitness, i.e. the
number, health, wealth of hir own descendants and other relatives. 
Certainly as long as one can provide some advantage to one's kin, or
continue to have more offspring oneself, I expect people to do those
things.  The "group" that one hangs out with typically does contain a
lot of immediate relatives and/or mates.  But the paper was
addressing only the specific issue of menopause.  It is a uniquely
human trait!  

Menopause implies things about the evolution of women, that they have
been doing "reproductive" things for decades after they stop
birthing, and this has been going on for a very long time.  That
shoots some holes in the notion of ancient female dependence on "man
the provider", among other things.

AR:  ii)	Tools ( Environmental change, etc ).
But tools are what bring a particular resource into the horizon of
the human. You can't get fish out of a river without a dart or
javelin or something. You can't switch to more plentiful but less
digestable food if you can't cook it.

LR:  I largely agree, but want to place this within a certain context
or view.  Actually, you can poison fish with certain tree barks, and
smash hard things with rocks, or spend more hours per day in order to
find more of something else.  People tend to do whatever gets the
biggest dinner for the time spent, other things equal.  When
conditions change such that a different behavior would serve one
better, one tends to invent/switch.

AR:  If a particular environment shrinks, either the human population
shrinks with it, or pre existing technology can be adapted and
extended to exploit other resources.

LR:  Yes!  Or, if population density increases, or climate changes,
or food species become more or less plentiful...  but not for the
purpose of increasing or otherwise managing the "population" per se,
it is a result of each individual trying to find a way to make more
babies.  

Lisa



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