Darwin-L Message Log 2:21 (October 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.

<2:21>From DARWIN@iris.uncg.edu  Mon Oct  4 23:20:57 1993

Date: Tue, 05 Oct 1993 00:27:32 -0400 (EDT)
From: DARWIN@iris.uncg.edu
Subject: Production of variation vs. selection in evolution and linguistics
To: darwin-l@ukanaix.cc.ukans.edu
Organization: University of NC at Greensboro

Jeff Wills makes an important point I think in discussing the two parts of
the notion of "sound change":

>I would agree that ease of articulation and perception may generate
>(motivate) linguistic variation--and here one might speak of expediency or
>striving--but the process of selection is sociolinguistic.  Whether
>variation arises from articulatory ease or language contact or imagination
>(neologisms), the success of the variants depends on a social process
>(which I think is the major external conditioning environment).

>In Tom Cravens' example from the dialect of Florence, you can attribute the
>variant /h/ for /k/ to whatever motive you want (e.g. articulatory ease or
>a bad cough). Such a variant is probably attested in many speakers of other
>languages and surely in other dialects of Italian.  But why did (this is a
>historical process) only the Florentines adopt/accept/extend this variant?
>Why are young speakers on the eastern boundary of the dialect area now
>speaking this way?  Presumably reasons of prestige or social realignment or
>something else in the environment--not because the sound change is "easier"
>for them than for speakers on the northern boundary who have been exposed
>to the same variant and have not changed.

When we look back on the history of a language any instance of a change
really involves both these phenomena Jeff describes: first the production
of the novel item, and then its spread through a speech community.  By way
of refining some of the parallels we have been drawing between linguistics
and evolution I would point out that this is precisely the distinction made
within population biology between the production of variation and its
spread by natural selection (or perhaps genetic drift).  Evolutionary
variation may be produced within a population by any of a number of means:
mutation, migration (the arrival of a new individual with a novel
genotype), genetic recombination, and so on.  Once variation is produced,
however, it is "tested" in the particular environment in which it arose. It
might be the case that a particular mutation arises in a population and is
immediately eliminated because it is disadvantageous, but had that mutation
appeared 10 years earlier or 10 years later, or at the same time but on the
other side of the river, it might have spread because the environment in
which it found itself would have been different.

Further, evolutionary biologists speak of variation as being "random", but
this does not mean that all variations are equally probable; indeed, for
biophysical reasons certain forms of DNA or protein variation are much
easier to produce than others, as are certain morphological variations.
When evolutionary biologists speak of variation as "random" they mean that
it is random with respect to whether it will be advantageous in a given
environment.  If mutations A and B are equally probably from a biophysical
point of view, but B confers a greater advantage upon its carriers in
environment X than does A, variant B will not be _produced_ at greater
frequency than A in that environment, although once it _is_ produced it
will have a greater chance of spreading through the population and becoming
"fixed" (present in all individuals) than A will.

Natural selection operates on a local scale, both geographically and
temporally, and changes that appear to have occurred randomly when seen
from a distance may in fact have been driven by local selection in a
particular set of environmental conditions that no longer exist.  I would
suspect that much language change (i.e., production of variation plus
spread to fixation) is likewise influenced by local "adaptation" to the
social environment, but perhaps this isn't the case.  The sociolinguists
among us (and the real population biologists like Kent Holsinger and Greg
Mayer) might be able to provide more insight into this.

Bob O'Hara, Darwin-L list owner

Robert J. O'Hara (darwin@iris.uncg.edu)
Center for Critical Inquiry and Department of Biology
100 Foust Building, University of North Carolina at Greensboro
Greensboro, North Carolina 27412 U.S.A.

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