Good mutations and Lamarkian mutations

David Campbell (
Mon, 1 Dec 1997 16:01:15 -0400

I'm afraid I do not recall the exact references, but a couple of recent
articles are relevant to these issues.
One study tested a large number of mutations for various enzymes;
most mutations did not significantly change the efficiency of the enzyme,
but some made it more efficent than the natural form; a few made it much
The apparently "Lamarkian" mutation pattern in bacteria seems to be
a case of selecting for mutations that generate a high frequency of
mutations (e.g., a mutation in a gene for a DNA error-correcting enzyme).
Usually, such mutations are bad, but in a stressful environment where
normal individuals cannot feed, high mutation rates make it more likely
that a useful mutation will arise. Similar logic applies to cancer
cells-the cells have high mutation rates, so many die but there's also a
chance that a cell will have a mutation enabling it to evade the body's
defenses, which is good for the cancer and bad for the organism.

David Campbell