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Dolphin brain

Richard Hall rhall at uvi.edu
Mon Feb 1 07:21:27 EST 1999

At 1:03 AM -0800 1/30/99, Michael C. Cheney wrote:
>In article <v04011700b2d0b1c2274f@[]>, rhall at uvi.edu (Richard
>Hall) wrote:
>| Natural selection does not appear to favor humans or dolphins of extreme
>| intelligence...at least there is no evidence that the mean has shifted one
>| way or the other.  It is only sufficient that animals possess sufficient
>What is your basis for this statement?  Are you saying that there is no
>evidence that the average human intelligence has changed throughout
>evolutionary history?  What time scale are you thinking of, and what
>evidence is there that it hasn't changed?

rlh replies:

There is no evidence that human intelligence has increased in the 50,000 -
200,000 years of homo sapiens.  Do not be fooled by the trappings of
technology and benefits of economics.  Despite the accumulation of
sophisticated knowledge and the creation of powerful machines, we are just
as rufus now as then.  Humans are social creatures and selection favors
social skills relevant to fitness.    Dolphins are social creatures and the
presumption probably holds for them as well.

Intelligence is basically a preadaptation that allows animals to exploit
their niche.  To suggest extremes in intelligence allowed creatures to
crawl, fly, or swim out of their niche is a stretch.  A position akin to
saying "We used our intelligence to become a new and improved species,
Homo intellectualis supremis or Homo retardis extremis"

Smart folks often have smart children but does that translate into
increased fitness?  The idea that intelligence is the dominating element in
reproductive success, that intelligence is inherited, that extremes in
intelligence are a criteria for speciation cannot be easily supported.   A
population is comprised of individuals with a distribution of
characteristics but "intelligence" is not a straight forward expression of
a few genes.   If we could prove that a set of conditions applied to a
population altered some statistically relevant aspect of the population's
intelligence quotient in an inheritable, reproducible manner then I would
probably recant.  But, we can't.


1.  Testing intelligence is problematic and we would need standardized
testing over many, many generations to form conclusions about changes in
IQ.  I took an IQ test when I was 12 years old after which my folks called
me an underachiever, sold my string of ponies, took me out of little
league, and made me take dancing lessons and go to Sunday school.  I guess
they really did know something about natural selection ;-).

2.  Cross species testing is frankly improbable beyond anecdotes...my dog
is smarter than your cat.  That lizard hasn't a clue about the nutritional
value of raisins.  My aren't those dolphins smart, do you think they would
watch and learn as much from TV as the average walrus?  Is the
"intelligence" of a bison the reason it does better in the open range than
a long horn steer?  Nonsense.  Irrelevant.

3.  Population geneticists have used natural selection to select specific
behaviors such as geotrophisms in fruit flies (forming populations of flies
that orient in different ways toward gravity.)  But as I recall selection
acted on variations in gravity sensing.)   The analogy would be using
selection to form populations with a high incidence of a specific visual
defect that influences behaviors.

4.   Obviously, a severely retarded creature is at disadvantage in passing
genes to the next generation unless thrown into a clad of severely retarded
creatures.  Domestic turkeys do not fare well in wild populations.  Wild
populations of turkeys quickley learn to be scarce during hunting season,
but does than mean we are selecting for smarter populations of turkeys by
hunting them and stupid turkeys by raising them?

5. It is easy to look at the history of humans and to form opinions about
how much smarter we appear now compared to those silly Egyptians and
Sumerians.  Technology has improved.  In some parts of the world, literacy
rates have improved.  But do either provide evidence that intelligence
measures (which we cannot agree on) have improved?  How many egyptians knew
how to design pyramids or make medicines compared to how many egyptians
know how to repair a computer or create a new designer drug?  I consciously
avoided mention of North Americans, but well, our senate is pretty
comparable to senates in ancient Rome and politics is still politics and
sex is still sex subject to redefinition in courts and polls.

Natural selection seems to favor the mean most of the time.  When
circumstances change, selection favors  better adaptations.  Intelligence
does not seem to be the critical factor perpetuating our species today.


> -mike
>Michael Cheney                                        cheney at ucla.edu

Richard Hall
Comparative Animal Physiologist
Division of Sciences and Mathematics
University of the Virgin Islands
St. Thomas, USVI  00802

rhall at uvi.edu

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