D'Abrera on Science and Philosophy
patfoley at saclink.csus.edu
Fri Jul 31 17:18:55 EDT 1998
The role of natural selection is well documented in Lepidopteran mimicry,
crypsis and other wing pattternings. If you doubt this examine the work
of E. B. Ford, H. Kettlewell, J. Turner and many others. This is not just
a matter of casual observation. Lots of careful data collection and
hypothesis testing has been done on the subject.
Evolution depends on natural selection working on whatever genetic
variability is available, and it is certainly true that this variability
has arisen in complex ways. Although the ultimate source of variability
is random mutation, the mutations express themselves through
developmental channels that have been themselves selected. Butterfly
variants show many constraints, as may be seen by an examination of F.
Nijhout's 1991, book The Development and Evolution of Butterfly Wing
It is no rejection of Darwin to argue that the course of evolution is
guided by not only selection but also the patterns of genetic
variability. In fact that is exactly what Darwin believed. To imagine
that the genetic variability is guided by supernatural forces is to reject
the consensus of scientists (reflected most notably in the work of Darwin,
Lyell and Newton) that natural phenomena depend on natural laws.
patfoley at csus.edu
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