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Re: the G- word, reply to Whitehead
Harriet Whitehead (whitehea@WSUAIX.CSC.WSU.EDU)
Sat, 17 Dec 1994 08:28:27 -31802
and behavior differences, asserting that this may be the link to inter
and intra-species behavioral differences, let me direct attention to the
work of behavioral geneticist Robert Cairns who studies agression
threshholds in rats. He found that the more "hair-trigger" (shall we say)
rats had greater concentrations of dopamine receptors at certain brain
cites. More importantly he sets out a framework for thinking about the
genetic component of behaviors that are diversely expressed within a
population, arguing as some animal breeder/trainers do that "What's easy
to train for is easy to breed for," and vice-versa.
I'm not sure I understand all his reasoning, but the argument is
roughly that when you find a population that is diverse as regards the
expression of a behavior, *and* the behavior (or attribute) exhibits a
noticeable training effect, the underlying genetic picture will be one
producing multiple easily altered developmental pathways. Selective
breeding can "tweak" the developmental timing intervals in such a way as
to bring out a more 'hardwired' 'genetic' version of the behavior, or,
conversely, it can recede or dampen the behavior. For starters, see his
"Development, microevolution, and social behavior," in *Psychological
Review" 97:49-65, 1990.
Harriet Whitehead
Anthro, WSU
On Fri, 16 Dec 1994, Ralph L Holloway wrote:
> 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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