Re: Technology and Intelligence

Ralph L Holloway (rlh2@COLUMBIA.EDU)
Wed, 8 Feb 1995 17:49:26 -0500

I'm sure Dwight Read will answer on his own, but let me jump in. The
chimp average brain size is about 400 cc, perhaps a little less, and the
gracile australos about 450. The robusts, except for WT 17000 (wich is
around 410 cc) are all around 520-53O cc.
But I still think that tool-making is but one aspect of social
behavior. The tripling in brain size requires at least two components to
be integrated: body size, i.e., allometric relationships, and secondly
brain expansion without concomitant body size increase. Very difficult to
know exactly how much is the former and the latter.
n Wed, 8 Feb 1995,
SS51000 wrote:

> I admire R. Holloway's prescience in not ruling out tool use among
> robust australopithecines; but back then it was quite parsimonious to
> hope and believe that the gracile form's different--and evidently more
> successful--development might be attributable to lesser commitment to
> culture in general, toolmaking/tool-use in particular. At any rate, the
> new evidence suggests more strongly than ever the great antiquity of
> precise manipulation of objects in the hominid line. This seems to have
> largely predated brain expansion, and therefore could have been what
> tipped strong selection *for* brain expansion. I admit that more is
> involved in the evolution of human intelligence than brain expansion;
> but one scarcely wants to suggest that a near-tripling of the gray
> matter was a peripheral factor! I am puzzled by D. Read's opinion that
> the 500 cc brain of the robusts already showed expansion was well under
> way. This is only about the size of a chimpanzee's brain. No doubt
> reorganization, associated maybe with lateralization and
> symbolization--as Holloway's work has suggested--was well under way; but
> not expansion. Maybe Dwight is thinking of WT 17000, the "Black Skull,"
> which I believe was somewhat smaller than 500cc? Seems to me a slender
> basis--one specimen--for concluding that a precision grip did not preced
> e expansion. Do you have more evidence, Dwight? --Bob Graber