Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!indri!nic.MR.NET!shamash!tank!ogil
From: ogil@tank.uchicago.edu (Brian W. Ogilvie)
Newsgroups: sci.bio
Subject: Re: Transfer of Instincts through Genetics
Message-ID: <2035@tank.uchicago.edu>
Date: 27 Feb 89 20:52:16 GMT
References: <1681@uswat.UUCP>
Reply-To: ogil@tank.uchicago.edu (Brian W. Ogilvie)
Distribution: usa
Organization: History of Science, University of Chicago
Lines: 73

In article <1681@uswat.UUCP> timw@zeb.USWest.COM () writes:
>
>If we agree that an animal is born with certain instinctive 
>characteristics (do we agree on this ?, leave homo sapien out
>of the picture, whole 'nother topic ?), I contend that genetically
>defined information determining these characteristics ABSOLUTELY
>MUST be transferred to the offspring. 

More or less, although recombination will affect the specific pattern
that the offspring receive. Mutation also plays a part, though it is
not as important in the short run as recombination.

>Where did this information originate ? I don't think it happened 
>overnight. Some salmonid at some point had to have learned that 
>if it didn't swim away from a shadow, it would be Osprey lunch.
>The Osprey missed this first 'instinct void' fish because it was old 
>and feable.   
>
>So, unless we're talking creationism vs. evolution, instincts are
>(1) learned and 2) passed on (IMVHO). 

NO! Instincts are passed on but not learned, at least not in the
usual sense of "learned." If an instinct is truly innate then learning
has nothing to do with its presence.

Let's take your osprey example. If a salmonid learns (because of a couple
of close calls, or what have you) to avoid shadows, its offspring are
going to be no more likely than the offspring of any other salmonid to
avoid shadows. In evolutionary biology's terms, there is selection for
a particular behavior, but the behavior is not heritable.

An alternate scenario which would produce an increased tendency to avoid
shadows would be one where, for some reason, the salmonid avoids shadows
due to some predisposition--without ever having seen an osprey. If this
behavior is genetically determined, then it is more likely to be passed
to the next generation than that of the salmonid which doesn't avoid
shadows. In this case, behavior is selected, and since the behavior is
heritable it will tend to spread through the population.

The difference between the two scenarios is that in one case the behavior
is innate (i.e. genetic) and in the other it is learned (or acquired).
Under current evolutionary theory there is no way that acquired characters
can be inherited. Natural selection acts on random mutation and genetic
recombination, not the so-called "Lamarckian" mechanism of the inheritance
of acquired characters.

The psychologist and biologist James Mark Baldwin did postulate an
evolutionary mechanism called the "Baldwin effect" where learned behavior,
while not inherited, bought time for natural selection to produce a
similar instinct. This mechanism has some subtle flaws. More recently,
certain biologists have propsed that many organisms (especially primates)
have been selected not for particular behaviors but for the ability
to learn quickly and effectively. This is an interesting approach to the
problem.

A good historical acount of evolutionary theories of behavior is
Robert J. Richards, _Darwin and the Emergence of Evolutionary Theories
of Mind and Behavior_ (Chicago: University of Chicago Press, 1987). For
an overview of the current controversy, Michael Ruse's book _Sociobiology:
Sense or Nonsense?_ has been recommended to me, though I mut admit that I
haven't read it. E. O. Wilson's _Sociobiology: The New Synthesis_
(Cambridge: Harvard University Press, 1975) is still the definitive
text, while Lewontin, Rose and Kamin's _Not in Our Genes_ gives an
impassioned presentation of the opposing view.

>Tim Walker
>Littleton, Colorado


-- 
Brian W. Ogilvie  /  ogil@tank.uchicago.edu
"Cartesianism is the most popular 'popular science' ever invented."
					--Noel Swerdlow