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Re: Hominid speciation, was h
Ralph L Holloway (rlh2@columbia.edu)
Thu, 20 Jul 1995 11:51:01 -0400
I always thought that there was a sort of "mini-adaptive radiation"
that took place around 2 MYA, but I never thought it might be related to
hybridization. I forget where I alluded to it, but my view was that that
stone tools, meat-eating (at least in so far as tools would be found
associated with faunal remains), tool-making and slaughtering sites, all
pointed to a sort of "revolution" (far too strong a term) of
symbollocally-mediated social behavior that would have enlarged adaptive
niches for exploitation. I can believe that hybridization could have
played a significant role in hominid evolution, but we are up against the
old lurking beast again, as represented in the biological species concept
and the morphological criteria sufficient to apply that concept to
paleontological evidence. When is there evidence of reproductive
isolation (which of course does not mean an impossibility of cross
feertilization and all the rest that Ernst Mayr has mentioned). The
burdun of proof however, must fall heavily on someone suggesting that
australopith A is a hybrid 'tween robust and gracile australopiths B and
C, or ditto for early or later forms of Homo.
Taxonomy is not one of my strong suites, and I've always viewed it
as a an intellectual convenience to have labels at the species level, if
for other reason than it helps students memorize the material! (Students,
hell, I need those labels myself!) I think hybridization will work well
for the Middle East and East European Neandertals, but beyond that, I am
skeptical.
Ralph Holloway.
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