Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!boulder!pell
From: pell@boulder.Colorado.EDU (Anthony Pelletier)
Newsgroups: sci.bio
Subject: Re: Transfer of Instincts through Genetics
Message-ID: <6925@boulder.Colorado.EDU>
Date: 24 Feb 89 17:26:48 GMT
References: <1681@uswat.UUCP>
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Reply-To: pell@boulder.Colorado.EDU (Anthony Pelletier)
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In article <1681@uswat.UUCP> timw@zeb.USWest.COM () writes:
>
>So, unless we're talking creationism vs. evolution, instincts are
>(1) learned and 2) passed on (IMVHO). Further, I conclude that,
>
>Tim Walker
>Littleton, Colorado

I think you are confusing "learning" with selection for those who "know."
Now, it is not as simple as that, as I will elaborate.  But, given
reasonable definitions, no "aquired"  or "epigentic" trait can find it's way
into the DNA, which is probably the only way in which
information is passed on to subsequent generations (Appologies to you
Hypotrichus-Cilliate-membrane fans).  A mechanism for passage of aquired
traits would probably have to work by selection at the protein level for a
variant that worked better and then have some "reverse translation" to get
back to nucleic acid form.  "learned" traits would be more complicated.
This seems like a nearly impossible mechanism for several reasons, but
I would be remiss not to acknowledge that not long ago, reverse transcription
was thought equally absurd.  
Cases of such Lamarkian inheritence have not been well documented (I don't
consider "the case of the midwife toad" to be well documented).

Until a mechanism for getting information from the protein level back to the
DNA level is found, it is not reasonable--and probably not necessary--to propose
such forms of inheitence.
What you have described can be explained in more conventional ways (this is
not to say the explanation is right), as someone else pointed out.
Also, what exactly "instinct" is is debatable.  Animals have culture that
pass tradition and behaviour on to offspring.  For example, the
"mother instinct" appears to be maintained as a learned behaviour in mammals.

There is an interesting, if not terrible testable, model that asserts that
morphological evolution is more visible in "Big-Brain" animals than in stupid
animals because learned behaviour that is passed through a population puts
pressure on to select for those individuals capable of performing the behaviour.

The observation is that in the expanse of time in which humans have come
up from ape and countless new bird species have developed, animals like the
alligator have remained virtually unchanged.  The mutation rate in alligator
DNA can be assumed to be on the same order of magnitude as that for mammals
and birds, so the difference must be at the selection level.
The "environment" in the sense that we usually mean has not changed more for
one than the other...the planet has looked alot the same for some time.
So some theorists have re-defined environment.  Rather than saying the
alligator is so well evolved for its environment that any changes are less fit,
these people believe that animals capable of learned behaviour
change their "environment" all the time so that they create new niches and
cause selection for a new trait.
For example: a bird is born with a slightly different beak (due to mutation)
and tries a new food--a berry it finds easy to get to with its beak.  It says
"damn, what a good berry.  I'll have me some more."  Other birds see the
bird eating the berry and think "that looks good, I think I'll try one."
(I own a bird, believe me they are very imatative).  Pretty soon, all the
birds are trying it, only not all of them are very good at it.  Now,
the food supply is not in terrible shortage for them...they won't die out.
But these berry-eaters hang out together at the tree and start to breed
more often amongst themselves than with others and sooner or later the
ones best at eating berrys are doing better in the new niche (i.e., the
ones with the best-suited beaks) and lo! a new species is born.

Ok, so it sounds a bit absurd; I didn't write it.  But there is some
circumstantial evidence for it.  One of the favorite example in humans
that these theorists mention is lactose metabolism.  Most adults
are lactose intolerent or at least lactase-.  There is a (reletively)
common mutation in which the juvenile lactase remains functional into
adulthood.  If you look around Europe for this isotype, you find it is
much more common in the Nordic countries.  
What's the difference?  Well, in the South of Europe, you farm; in the
North of Europe, you raise dairy cattle, or so the argument goes.
I'm not convinced either.  But this might be an example of a learned
behaviour adding to selection.  The problem is you really can't do
any experiments on this; you are stuck with correletive studies.
But, such a mechanism could explain how a learned behaviour appears
to get into the gene pool.

-tony