|
|
Re: Canine Reduction
JOHN LANGDON (LANGDON@GANDLF.UINDY.EDU)
Thu, 23 Feb 1995 10:29:07 -0500
In message Ralph L Holloway writes:
> I'm not a tooth man, but I thought that the canines preventing lateral
> jaw motion was no longer an accepted viewpoint, as manyb primates with
> large canines do some amount of rotary chewing.
>
> > M. Hill tentatively raises the mastication hypothesis for canine
> > reduction. J. Langdon, having admitted that the evolution of hominid
> > intelligence is difficult and cannot be explained with certainty,
> > concludes by pronouncing that side-to-side chewing *is* the reason for
> > canine reduction! This hypothesis arguably is at least as problematic
> > as the tool hypothesis but with none of the parsimonious impications
> > of the latter. Why so open-minded on intelligence, but so dogmatic on
> > canine reduction, John? --Bob Graber
You got me. I threw in the comment (with thoughtless dogmatism) about canines to
make a point about the tool hypothesis.
Still, I think the chewing explanation was a good one. I don't know where or
when I encountered it, but I scooped it into general knowledge because it made
so much sense. I will check out the critical citatations (thanks). Certainly
there is something different about the early (and later) hominid jaw in its
shape and extent of lateral movement, in the helicoidal occlusal plane and in
the emphasis on massive grinding, that distinguishes it from other primates.
Reduction is significant in A. afarensis. If canine reduction is related to
changing social behavior or to tool use, this is earlier than such models imply.
I am not convinced by most stories of the evolution of human sexual and mating
behavior, but the party line is that male-male competition of the type that once
selected for canines is still important today and was much more important for
australopithecines, as indicated by the great degree of sexual dimorphism (e.g.
afarensis again). Therefore I think mechanical mechanisms are more attractive as
explanations for reduction.
JOHN H. LANGDON email LANGDON@GANDLF.UINDY.EDU
DEPARTMENT OF BIOLOGY FAX (317) 788-3569
UNIVERSITY OF INDIANAPOLIS PHONE (317) 788-3447
INDIANAPOLIS, IN 46227
|