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From: ccb8m@viper.cs.Virginia.EDU (Charles C. Bundy)
Subject: Re: Big Brains and Evolution
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References: <DCA68n.DuL@murdoch.acc.Virginia.EDU> <806482865snz@whitestn.demon.co.uk>
Date: Thu, 27 Jul 1995 17:35:45 GMT
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In article <806482865snz@whitestn.demon.co.uk> Bob@whitestn.demon.co.uk writes:
>In article <DCA68n.DuL@murdoch.acc.Virginia.EDU>
>           ccb8m@uvacs.cs.Virginia.EDU "Charles C. Bundy" writes:
>
>> I'm not certain intelligence arose as a "direct" response to environmental 
>> stimuli.
>
>> Before you can have a Big Brain(tm) some major physical changes must occur.
>> Assuming these changes are the result of evolutionary pressure, the Big
>> Brain is a side effect NOT a direct result of evolutionary pressures. 
>
>By this I assume that you are suggesting that for whatever reason selection
>pressures existed for certain physiological changes, and the more developed 
>brain came along as a side effect of these changes but then subsequently 
>proved useful.

Well put! The physiological changes that were a direct result of evolution
improved our ancestor's survival rate, but resulted in a loss of physical
capability.  To make up for the physical compromise something had to fit
the bill.  I think it was the Big Brain(tm) which allowed weaker physical
subsystems to operate in concert resulting in synergy.

>
>I'm certainly no expert on human evolution but I think this could be 
>right.  I could envisage the following stages of evolution taking place.
>
>1.  Environmental changes cause terrain to shift from forrest to savanah.
>    On an open plain there isn't much tall vegetation about, so it's
>    an advantage to be tall and have good long-distance eyesight.
>    You can spot oncoming predators more quickly, and spy on your prey
>    from a farther distance.
>    Rather than simply developing a much larger body size (which would be
>    expensive in terms of the energy needed to run it), a more
>    economical solution is to evolve an upright stance.

It probably went something like this:

   Savanah would be interspersed with "oasis" spots of tree and water which
   is life for an animal.  When the water/tree was used up animals made
   the trek to another oasis or perished.  Unfortunately ITS HOT out there
   on the plain.  The best way to get from dying oasis to lush oasis is to
   improve heat dissipation.  One way to do this (so ya don't fry) is to
   minimize the skin surface area that absorbs solar radiation.  The optimum
   is to be a thin horizontal line which presents minimum area at the hottest
   part of the day, which is 12 noon when the sun is directly overhead.  Thus
   an upright stance means we can go farther (more stamina) before frying.
>
>2.  An upright stance means that it's harder to pump blood up to those
>    vital sensory organs in the upper part of the body (head).

Well I've seen this bandided (sp?) about, but I can pick my kitty cat up
so she is horizontal wrt the ground for quite a while, and the only
result is she gets pissed off.  :)  I don't think blood transport is an
issue/problem between quad/bipedal locomotion.  IE bats spend a lot of time
hanging upside down, but the only evolutionary change that has been
documented is that their feet are designed to be locked in place.

>
>3.  Running on four legs is faster than two, so the exclusively upright
>    stance comes at a price.  Humans don't have much in the way of

Umm w/ the exception of the cheetah and certain horses man is the fastest
land animal in the 1/4 mile.  No other land animal can match us over spans
longer than 10 miles, but of course most animals like wolves, etc don't
range that far, say 20mi diameter.  Of course quadrapeds have distributed
running gaits so they are more powerful but, not always faster.

>    defenses (tough skin, fangs, claws, exceptional strength, etc) so
>    survival chances are reduced if you're being chased by something big
>    and hungry.  Also you can't get up to quite the speed you used to

Well, back to the savanah, eating/drinking is more important than worrying
about a predator chasing you, since it is of more immediate concern and
occurs more frequently. Predator concerns would only outway eating concerns
when the predator is on top of you.  Mating would occur less frequently and
only outway eating/not being eaten a few times a year.

>So you can see that pressures originaly not related to intelect could
>eventually have given rise to the development of a Big Brains(tm).    
> 
>> If intelligence were solely a result of pressure, would other species also
>> develop "intelligence" as a response to the environmental pressure of
>> another species? Are there other intelligent species on earth who as a
>> result of their Big Brains(tm) avoid homo-sapien?
>
>Hmm, a sort of intellectual arms race, do you mean?

Yes, if intelligence was the pinacle of evolution that some people think
it stands to reason that more than one species would have it, eh?  If
instead it required a complex set of physical mods and only was "useful"
in overcoming physical downgrading fewer species would select for it.

So maybe intelligence isn't the ultimate eh?  Or there are more intelligent
species than we know...

Charles Bundy
ccb8m@preferred.com
