Re: genetic mutations are not just random

["Charles Brown" <CharlesB@xxxxxxxxxxxxxxxxxxxxx>]

This is remarkable, I mean Lamarckian ( by which I don't mean there can't be new evidence of validity of Larmarckian mechanisms)

Careful, Ricardo, you will be accused of Lysenkoism.

CB

>>> rduchesn@xxxxxxxx 12/07/00 01:08PM >>>

The claim that there is
evolutionary progress, or  any intelligible pattern in
evolution is a difficult one for many biologists to accept,
if only because they take it for granted that mutations
arise without regard to whether
they are useful or not to the organism. But I disagree. I believe
that genetic change can be viewed as a rational strategy for survival,
that somehow organisms
themselves re-engineer their DNA so as to maximize their survival.

There is an argument out there
which states that once mammals emerge, with their larger brains,
mutations occur at steadily faster rates over time. It was known that
mammals evolved at a higher rates than previous reptilian species. But
an explanation now says that mammals did so because their larger brain
instigated an internal pressure for a higher number of mutations, or
for a higher "fixation" of mutations in the descendants holding the
mutant gene. The key difference seems to be in the number of
fixations: "the number of mutations arising per unit of time is the
same for frogs amd mammals, but the fraction of those mutations that
are fixed is higher for mammals..." (Allan Wilson, Scientific
American, 1985). Wilson argues that this internal pressure comes from the
greater mammalian  capacity of  the brain to learn and imitate. In
other words, mammals introduced new selective pressures that cultivated
fixation of mutations that were complementary to new learned
behaviors.