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From: andrewt@aisb.ed.ac.uk (Andrew Tuson)
Subject: Re: Lamarckian Evolution
Message-ID: <D4I282.Dx6@aisb.ed.ac.uk>
Sender: news@aisb.ed.ac.uk (Network News Administrator)
Reply-To: andrewt@aisb.ed.ac.uk (Andrew Tuson)
Organization: Dept of AI, University of Edinburgh, Scotland
References: <1995Feb4.005816.16390@gdunix.gd.chalmers.se> <3i5nvj$7ki@mailer.fsu.edu> <1995Feb24.020541.4049@inca.comlab.ox.ac.uk>
Date: Fri, 24 Feb 1995 10:24:02 GMT
Lines: 50

In article <1995Feb24.020541.4049@inca.comlab.ox.ac.uk>, trin0008@sable.ox.ac.uk (Rick Heylen) writes:

Hi Rick!

# Imagine an environment where the temperature oscillates every few days
# between two extremes- hot and cold. There are bacteria living in this
# environment and metabolising food and reproducing. The type of bacterium
# which reproduces well in the hot environment doesn't do so in the cold
# environment and vice versa however there is only a small genetic change
# necessary to interconvert them.

[Stuff deleted!]

# In an environment where some factor critical to survival
# oscillates in the space of about two or three generations then you could
# expect this sort of thing to take place.

NO! What would in fact evolve at the genetic level is one type of bacteria with
a phenotypic trait of the form `if cold then A if warm then B'....

Same effect (i.e. bacteria are well-adapted to a constantly changing
environment) - no Lamarkianism required.
 
# It would be very difficult to prove however as you would have to show that
# the change in the offspring was made at the genetic level, the change is
# directly correlated with this environmental factor and that the increased 
# fitness of the children is based mainly on the genetic change. Further
# you would have to show that this DNA altering behaviour is also shown in the 
# children and is reversible otherwise it's just an example of the parent
# juggling the child's genomes  randomly in the hope of making some change

But as I said there is a perfectly valid neo-Darwinian adaptation that would
have much the same effect.

# Lamark did come up with some really crackpot ideas and there's probably
# a large knee-jerk factor in the dissmisal of MILD lamarkian type things
# such as the above. If the above in infeasable or somehow subsumed by the
# revised Darwinian theory of evolution then please inform me.

The above would simply not evolve - see above.

Lamark was not crackpot at the time however - the idea of 'inheritance of
acquired charcteristics' was thought an obvious truth then.

Best Wishes

Andrew Tuson (andrewt@aisb.ed.ac.uk)

Department of Artificial Intelligence, University of Edinburgh, Scotland, UK.

