Here's a question/observation to include in the discussion of origin of
genetic variation. I think that this is relevant especially with respect
to some of Glenn's and Walter's (BTW welcome back, Walter) arguments.
Doesn't the existence of *relatively* constant molecular clocks suggest
that mutation rate is independent of generation time? Thus, mutation rate
is determined by exogenous factors such as environmental mutagens (e.g.
oxidation agents) or radiation that damage the germ-line DNA (time
dependent) rather than by replication error (generation dependent).
I believe that this helps Glenn's argument along abit.
Obviously, there are some exceptions to this and immunogenetics may be one
of them (help me out here, Steve).
I've heard this generation time argument ad nauseam as a result of Denton's
book and Pandas but I think it's wrong. I'm willing to be corrected
however.
Of course, all molecular clock arguments assume the legitimacy of the
conventional geological time scale.
Terry G.
_____________________________________________________________
Terry M. Gray, Ph.D. Department of Chemistry and Biochemistry
Calvin College 3201 Burton SE Grand Rapids, MI 40546
Office: (616) 957-7187 FAX: (616) 957-6501
Email: grayt@calvin.edu http://www.calvin.edu/~grayt