Darwin-L Message Log 1:161 (September 1993)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.

<1:161>From HOLSINGE@UCONNVM.BITNET  Fri Sep 17 06:40:37 1993

Date: Fri, 17 Sep 1993 07:29:21 -0500 (EST)
Subject: Re: Re: Lamarkianism in linguistic change
To: darwin-l@ukanaix.cc.ukans.edu

Even though I am a population geneticist, I tend to agree with Peter Junger
that the definition of organic evolution as "a change in the allele frequencies
of a population..." (to quote Anax) is too restrictive.

Inbreeding, for example, doesn't change the frequency of any alleles, but it
does change the relative frequencies of different genotypes, making homozygotes
more common and heterozygotes less common.  Similarly, recombination breaks
down non-random associations of alleles within gametes, changing the frequency
of multi-locus genotypes.

The definition of organic evolution I have always preferred is "a change in
the genetic composition of a population over time..."  I realize, of course,
that Darwin wouldn't have recognized this definition in this form, but if we
were to change the words "genetic composition" to "hereditary characteristics"
or some similar phrase I suspect he would agree immediately.  (It's always
nice to invoke the dead because they can't disagree with us.)

Including some notion of genetic or hereditary change is important.
Evolution hasn't happened unless there is some difference between the
characteristics of ancestors and descendants.  If the differences in
appearance between ancestors and descendants are purely environmental
modifications, then what we see is organisms developing in a different
environment, not organisms with different characteristics.

-- Kent

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