Re: CREATIONISTS ON THE
HARRY R. ERWIN (herwin@mason1.gmu.edu)
27 Jun 1994 15:07:13 GMT
NICHOLLS PHILIP A (pn8886@thor.albany.edu) wrote:
: Homo erectus has begun to interest me of late. According to speciation
: theory, in order for speciation to occur you have to have reproductive
: isolation at some point. If the multi-regionalists are correct (and I
: am not saying that they are correct) then there has been no reproductive
: isolation during the transition from Homo erectus to Homo sapiens. If
: this is true, then we need to ask if vectored change alone over time is
: enough to justify changing species. In other words, an argument can
: be made that Homo erectus should be renamed Homo sapiens.
You can have a shift in characteristics via two alternative mechanisms
to reproductive isolation:
1. A global change in the environment that changes the fitness function
for the species. In that case, you would see a global change in the
characteristics of the species, or
2. A local environmental change that results in a local race modifying a
characteristic to the point that a new fitness optimum becomes
accessible. The characteristic then spreads through the species.
The issue of whether the later population differs from the earlier
population in the same way that two simultaneously existing species
differ cannot be answered. You also have the issue of two local
populations that do not interbreed, but still sharing genes via
intermediates...
--
Harry Erwin
Internet: herwin@gmu.edu
Working on Katchalsky nets....
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