Tools & Canine Reduction

Tue, 21 Feb 1995 11:06:57 CST

J. M. Ottevanger asks about the connection between manipulative
intelligence and canine reduction. The hypothesis is that selective
pressure for large canines relaxed because their main function,
fighting, had been taken over by hand-held weapons. C. Loring Brace
argues rather convincingly that under relaxed selective pressure,
structural reduction is to be expected because the "probable mutation
effect" is to inhibit rather than enhance a growth process. (I prefer a
bioenergetic interpretation according to which wasting energy is
selected against.) The idea seems to have originated, though, with
Darwin himself, who wrote these beautiful lines in *The Descent of Man*:
"The free use of the arms and hands, partly the cause and partly the
result of man's erect position, appears to have led in an indirect
manner to other modifications of structure. The early male forefathers
of man were . . . probably furnished with great canine teeth; but as
they gradually acquired the habit of using stones, clubs, or other
weapons, for fighting with their enemies and rivals, they would use
their jaws and teeth less and less. In this case, the jaws, together
with the teeth, would become reduced in size, as we may feel almost sure
from innumerable analogous cases . . . [such as] the reduction or comple
te disappearance of the canine teeth in male ruminants, apparently in
relation with the development of their horns; and in horses, in relation
to their habit of fighting with their incisor teeth and hoofs."
So Darwin clearly saw tool use, bipedalism, and canine reduction as
the original hominid "package." It seems likely that tool *making*,
language, and brain expansion were fostered by--or even were part
of--this same package; this parsomonious interpretation at any rate
seems highly consistent with the work of Ralph Holloway, Sue
Savage-Rumbaugh, and no doubt others of whose work I am (even) less
knowledgeable. --Bob Graber