Re: MN (resp. to J. Witters)

RDehaan237 (
Tue, 31 Mar 1998 06:07:51 EST

In a message dated 3/30/98 1:39:46 AM, WITTERSJ@ESUVM.EMPORIA.EDU wrote:

<<A separate
consideration within the "Darwinian scenario" is the issue of
speciation. As Gould has argued, the microevolutionary model of
change cannot explain what is observed in the fossil record. Would
Gould argue that speciation occurs by processes independent of any
Darwinian (evolutionary) process?>>


Of course not. He gives an example in the Natural History article of snails
from the Bahamas that he studied. He found snails on a single mud flat that
had gradually changed over 10,000-20,000 years. He showed that the snail
changed gradually from an extinct species to the modern species. While he
doesn't explicitly spell out the Darwinian mechanism he gives no reason to
suppose that any other mechanisms were involved.

But the point is that the change only produced another *species* of snails,
no higher or more general forms. That's the point. Microevolution (Darwinian
mechanisms) does not produce macroevolutionary innovations. If you have
examples of general, more inclusive organisms arising specific ones, let's
have them.