From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!ogicse!henson!milton!wcalvin Mon Dec  9 10:47:38 EST 1991
Article 1821 of comp.ai.philosophy:
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>From: wcalvin@milton.u.washington.edu (William Calvin)
Newsgroups: comp.ai.philosophy
Subject: Re: There are no "steps" in evolution
Message-ID: <1991Dec3.061714.25312@milton.u.washington.edu>
Date: 3 Dec 91 06:17:14 GMT
References: <1991Dec3.022827.6644@monu6.cc.monash.edu.au>
Organization: University of Washington
Lines: 37


Generalists in the animal world have an interesting problem (as I briefly
discussed in my 1990 book THE ASCENT OF MIND):  an efficient
specialist in the current foods and climate can always beat out a jack-of-
all-trades generalist.  The generalist has to carry around the physiological
mechanisms for digesting many kinds of food (instead of one food, with
great efficiency), the cognitive mechanisms for finding and catching the
many kinds of food, the body insulation and heat-loss mechanisms for
dealing with various climates, etc.
      An example of where specialists are beating out generalists is in
the forests of Uganda, where chimpanzees (the only other surviving
omnivore among the apes besides us) are losing out to the local monkeys
who can harvest the fruit faster than the chimps (see Michael Ghiglieri's
book IN THE MOUNTAINS OF THE MOON).
      A more homely example of a generalist is the traveler who takes
clothing for every possible contingency -- and discovers that the carry-
on-luggage-only travellers get the only taxicabs.
      The only way that generalists survive in the long run is if the
name-of-the-game keeps changing -- and faster than evolution-for-
efficiency can manage to track the climate changes.  Suppose that the
weather in Chicago changed so rapidly from frigid to steaming that carry-
on-only travellers were wiped out, and only the pack-for-all-contingencies
types survived.  Abrupt climate changes (such as the Younger Dryas in
Europe 11,500 years ago, an abrupt cooling within 20 years that lasted
for 800 years before abrupt rewarming) create an advantage for animals
than can abrupt change strategies for making a living, tolerating the
climate, and still successfully reproducing.  There were lots of such
changes during the ice ages of the last 2.5 million years.
      Evolution isn't known for efficiency:  good-enough engineering
is the more appropriate analogy (e.g., our blood oxygen is typically
regulated by sensing the CO2 level rather than O2; they're usually
reciprocally related but pilots can get into big trouble with anoxia).
My guess is that we owe our generalist brains to our omnivorous diets
and the abrupt climate changes that gave us an advantage over the
specialists.

      William H. Calvin                 WCalvin@U.Washington.edu


