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Re: the G- word, reply to Whitehead
Ralph L Holloway (rlh2@COLUMBIA.EDU)
Fri, 16 Dec 1994 11:44:05 -0500
Mike Lieber mentions dog breeds and possible neurobiological differences.
As someone particularly interested in human brain evolution, I spent the
last 30 years with my antenae up high listening for such information. I
know of none. There is not, as far as I am aware, one single
neurobiological observation that makes any connection between variation
in dog breed behavior and variation in the dog CNS. At what level of
neurobiological organization this variation takes place is unknown. There
is a German neurobiologist, name of Dieters Kruska, who has been
investigating neural orginizational differences between domestic and wild
swine, and does find minor differences in relative sizes of the brain as
well as nuclei size differences. The most exciting this I saw recently
was on "The Brain Within Us" program, hosted by David Suzuki. Two
different species (races?) of vole were tested for maternal behavior and
neural receptor sites for oxytocin. The prairie vole and the mountain
vole seemed to have just about identical brain sizes and internal
structure. Thge density of receptor sites made the prairie vole look as
if it were an entirely different kind of animal, the entire surface and
many regions of the internal brain being lit up like a christmas tree,
whereas in the mountain voile only a very tiny patch were effected.
Oxytcin is the hormone involved in maternal behavior that we think of as
"cuddling". The praire vole, when separated from newborn, immediately
went back to hen in the next and "cuddled" them. Not so the mountain vole.
These receptor sites are, in my thinking, closer to gene activity
than size per se. The point is that size parameters, while interesting,
may actually hide (or rather, mask) important neurobiological levels of
organization that DO more closely have some causal link with behavioral
variation.
Let me throw down the guantlet a little further. Can one really
imagine that the differences between gibbon, orang, chimp, and gorilla
behavior can be explained by brain sizes? By EQ's? By Nc's?This is one
rerason why I have despaired so much over the last 30 years in trying to
preach reorganization as well as size. Both are important, but current
paleoanthropologists and evolutionary biologists such as Gould have
ignored the latter. Happy holidays, Ralph L. Holloway.
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