Re: Tools and Brain Expansion

Ralph L Holloway (rlh2@COLUMBIA.EDU)
Thu, 23 Feb 1995 15:54:18 -0500

Coul;d I just mention that Darwin's work in which he mentions human
evolution goes back to the 1870's, long before any australopithecines or
even Homo erectus were found. At best, there were neandertal fossil. It
would be fascinating indeed to know what Darwin might say about today's
hominoid and hominid records in the context of modern physiology and
primate behavior. Would he plead so strongly for parsimony?
R. Holloway
On Thu, 23 Feb
1995, SS51000 wrote:

> J.Langdon writes,
> >In tool, social, and foraging models we face the problem of why other species d
> >not have big brains. After all, chimps make and use tools, have complex
> >societies, and face similar foraging problems. Perhaps there is a threshold
> >effect -- once brains reach a certain size, positive feedback takes over and
> >increase proceeds exponentially. tion for
> >
> Note, though, that tool use and tool making is extremely rudimentary,
> which, in conjunction with the small brains of chimps, gives technology
> precisely the presumptive temporal priority required for it to have been
> causal. Therefore I think of a threshold not of brain size, but of tool
> dependency: at some point our ancestors became dependent enough on tool
> use that bipedalism and canine reduction--and brain expansion and
> symbolization--all were subject to growing selective pressure. I think
> it of utmost importance that only the Darwinian theory, which puts tools
> in the role of prime mover, allows explanation of all these hominid
> trends at once. From my perspective, any attempt to explain some one
> of the features suffers a considerable handicap in terms of parsimony.
> To compete with Darwin, you need to have a very strong argument that
> he was mistaken, or come up with a more compelling explanation of
> hominid features in general--especially the bipedalism/canine reduction
> combination, but preferably also language and brain expansion. It is
> amazing that the rather short-lived rotary-mastication hypothesis, about
> which I too am in search of references (a major one being Jungers in
> *Current Anthropology* of 1978), which is far less relevant than tools
> to *any* of the other hominid features, seems to be the most serious
> challenge to Darwin's theory in the 124 years since it was presented.
> But then he was Darwin, wasn't he? --Bob Graber