Re: Talking apes

Garry DeWeese (deweese@ucsu.Colorado.EDU)
Wed, 15 May 1996 09:36:46 -0600 (MDT)

On Tue, 14 May 1996, Braxton M. ALFRED wrote:

> ...
> The criterion for accepting a species is reproductive isolation ("in
> nature")...
> I apologize for getting "into" this. It is, however, important to realize
> that taxonomy cannot be done on an attribute by attribute basis - this
> form has a jaw shaped like that one so they are related. It simply
> does not work that way.
This posting prompted the following comments:

The concept of "species" is a very difficult and fluid one at the
moment. The traditional taxonomy was based on morphology (shape of jaw,
length of femur, etc.) which has since proved untenable. The emphasis
then shifted to reproductive isolation; again, untenable. As examples,
consider the lion and tiger--clearly distinct species, we would
intuitively say. But given two skeletons, only a very highly trained
specialist could distinguish bewtween them, and the variations would be
less than variations demonstrable between many pairs of members of the
same species. Further, they can interbreed--resulting in "ligers" and
"tigons." Or take a species of frog found along the Mississippi from
Minnesota to Louisiana (I forget the scientific name, and am not where my
files are--perhaps someone else can supply the technical information
here). The Minnesota frogs can interbreed with Iowa frogs, who can
interbreed with Missouri frogs, ... to Louisiana. But the Minnesota
frogs cannot interbreed with the Louisiana frogs (maybe
Scandanavian-accented mating calls don't translate into Cajun accents? ;) ).

Now the emphasis seems to be an a cladistic taxonomy (based on
phylogenetic similarity). But it is unclear if this is going to prove
any more stable in the long run than morphology or reproductive

Conclusion? "Species" is probably not a natural kind term but rather a
"cluster concept." Thus the concept cannot bear the burden placed on it
by either the YECs or in recent posts on this reflecter
claiming/disavowing species relationships of A. afarensis, H. erectus, etc.

A final note: I, like most others apparently, have been mute in recent
weeks as I watched the Morton/Fisher debate unfold (and as the pile of
term papers to grade and finals to write grew). It was
most interesting, with a very impresive amount of technical data on both
sides. Thank you, Glenn and Dick, for teaching me much. Now begins the
more difficult task of theory evaluation. The two paradigms of the flood
are contrary but not incommensurable. Perhaps others now could offer
perspectives on the strengths and weaknesses you perceive in the two

Garry DeWeese