Darwin-L Message Log 5:183 (January 1994)

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.

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<5:183>From ahouse@hydra.rose.brandeis.edu  Thu Jan 27 15:32:48 1994

Date: Thu, 27 Jan 1994 16:42:53 -0500
To: darwin-l@ukanaix.cc.ukans.edu
From: ahouse@hydra.rose.brandeis.edu (Jeremy Creighton Ahouse)
Subject: what evolution is...

        In reading a recent post to the sci.bio.evolution newsgroup I came
across an introductory essay by Chris Colby (colby@bio.bu.edu).  It
included the following:

>WHAT IS EVOLUTION?
>
>Evolution is a change in the gene pool of a population over time. A
>gene is a hereditary unit that can be passed on unaltered for numerous
>generations. The gene pool is the set of all genes in a species or
>population. The English moth, _Biston__betularia_, is a frequently
>cited example of observed evolution. In this moth there are two color
>morphs, light and dark. Black moths, which initially were rare,
>increased in frequency as a result of their habitat becoming darkened by
>soot from factories. Birds could see the lighter colored moths more
>readily and ate more of them. The moth population changed from
>mostly light colored moths to mostly dark colored moths. Since their
>color was primarily determined by a single gene, the change in
>frequency of dark colored moths represented a change in the gene pool.
>This change was, by definition, evolution.

..

>WHAT ISN'T EVOLUTION?
>
>For many, evolution is equated with morphological change, i.e.
>organisms changing shape or size over time. An example would be a
>dinosaur species evolving into a species of bird. It is important to note
>that evolution is often accompanied by morphological change, but this
>need not be the case. Evolution can occur without morphological
>change; and morphological change can occur without evolution. For
>instance, humans are larger now than in the recent past, but this is not
>an evolutionary change. Better diet and medicine brought about this
>change, so it is not an example of evolution. The gene pool did not
>change -- only its manifestation did.

        My question to the good members of the Darwin list is; when did
this identification of evolution with changes in gene frequencies become
entrenched/started/is it changing?

        My sense in reading of Darwin and other 19th century writers is
that evolution is precisely concerned with changing morphology and the
notion of a "tree of life."

        I am not as happy about the triumphant move that makes evolution
coextensive with gene frequency changes as the current story seems to be.
I wonder if this is another move in the hegemonic accretion of terms by
molecular biology/genetics or if this idea has a different historical
origination.

        Was the identification of evolution with gene frequencies the key
insight (or trade) that made the new synthesis possible and the one that
left the developmental view out (Ron Amundson?).

        Thanks,
                Jeremy

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