"selfish genes" vs. "selfish DNA"

arlin at ac.dal.ca arlin at ac.dal.ca
Thu Feb 18 19:59:09 EST 1993


It might be useful to draw a distinction between "selfish DNA" and "selfish
gene."

As Peters and Jones have pointed out, Dawkins has written an influential book
called _The Selfish Gene_, and it is perhaps best to associate the phrase
"selfish gene" with Dawkins's major thesis, which is that familiar
evolutionary processes can be explained from a "gene's eye view," in which the
"function" (metaphorically speaking, of course) of genes is to promote
their own perpetuity-- to be "selfish."  Dawkins proposes this as an
alternative mode of reference for explaining apparent adaptations, to be
compared to the traditional view in which the central explanatory entity is
the individual (i.e., the population of individuals in a species).

[My personal reading of Dawkins is that this view is offered as an equally
valid, but incommensurable, alternative mode of explanation to the traditional
mode.  Other readers, however, believe that Dawkins gives primacy to the
gene-centered view (e.g., Gould in his vicious assault on Dawkins and anyone
who favors his arguments, in a recent NYT Book Review).]

By contrast, the words "selfish DNA" should probably be associated with the
arguments of Crick, Orgel, Doolittle and Sapienza to the effect that certain
elements of genomes (e.g., transposable elements) can increase their copy
number and spread without conferring benefits to their hosts.  Others had
proposed that transposable elements and highly repetitive sequences served
unknown but important functions (e.g., in regulating nuclear volume, etc.)
that constituted individual adaptations, but these biologists realized that an
adaptive explanation was not necessary.  A sequence can conceivably arise and
spread through its own tendency to be over-replicated, whether or not it is
adaptive for the individual-- as long as it isn't deleterious.

The relationship between the two is perhaps that "selfish DNA" represents a
set of conditions in which one is obliged to adopt the gene-centered
perspective of Dawkins, even if one prefers normally to use the Darwinian 
perspective (which gives primacy to individual adaptation).


Arlin Stoltzfus
Department of Biochemistry
Dalhousie University

 



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