Punctuated Human Evolution WAS Re: Definition of evolution

James P. H. Fuller jim at crom2.rn.com
Thu Nov 7 19:57:43 EST 1991

 john at publications.ccc.monash.edu.au (John Wilkins) writes:

> I'm a dilettant (=non-biologist), but I thought Gould and Eldridge estimated
> that the speciation period was typically around 10% of the species' "life".
> Given that homo sap sap is around 500,000 years old, and that we could expect
> on purely biological grounds that the species would survive at least 5
> million years, perhaps we are still in the process of speciating?

     Well, speaking to the logic of the situation, a "speciation event" is
complete when the new species has reached reproductive isolation from its
parent population.  Homo sap is IMHO a good species worthy of its Latin 
binomial because of being reproductively isolated from all other groups in
genus Homo, since they're all dead.

     I am of course willing to believe that H. sap is still subject to mutation
and to various selection pressures, so that new alleles could be appearing at
some rate and the frequencies of existing alleles could be changing over time.
Does that mean that human evolution is still going on?  It depends strictly on
what you choose to emphasize in your definition of evolution:  speciation it-
self or just the ongoing changes in the characteristics of populations (or
"the march of frequency distributions through time" as SJG put it when he lec-
tured here.)
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