Q; WHY left hemisphere language?

David Baldwin 503-686-2598 dbaldwin at decoy.uoregon.edu
Thu Feb 16 19:34:08 EST 1995


In article <3i069r$eh at oravannahka.Helsinki.FI>,
Dag Stenberg <stenberg at cc.Helsinki.FI> wrote:

>2) in some species one of the two possibilities has gradually been
>eliminated from the population. Why is right called "right", and left in
>many languages is synonyme to "clumsy"? Maybe that terminology is very
>ancient, and those people were less likely to survive due to defective
>division of tasks between brain parts. 

Lemme guess... was this penned by a right-hander, per chance?  :-)

As I recall, all three presidential candidates in the US (last election)
were _left_ handers.  I'd expect the proportion of successful left handers 
to increase in situations of uncertainty and change, where creativity and 
non-linear/non-logical thinking is at a premium. 


>- second, as far as I have understood, several samples indicate that
>about 5-10% of humans are left-handers, and of those, about half have a
>language specialization in the right hemisphere, without previous
>trauma. I wish I knew how large and representative these population samples
>are, and how valid the assessment of laterality. Cave paintings from
>early Cro-Magnon times indicate 80% right-handers at that time.

I'm curious what is the current (and historical, for that matter) proportion
of left-handers among various professions -- say, architects or artists?  
I'd think a population of artistic individuals might be a more appropriate 
comparison for the population of Cro-Magnon cave painters, and that within 
such artistic samples the proportion of left-handers may be higher than found
in the general population.
 
Aside from acknowledging that no one knows the answer to the original question
here, my own guess is that language is a "big project", and required lots of 
spare computing power.  Similarly, as I recall, music is processed in right
hemisphere by most people, but in the left hemisphere of musicians (relatively 
more processing).  Since the right hemisphere is somewhat more taken up by or 
involved with negative emotions and perhaps with threat-monitoring [REFS see: 
Lee et al, 1993, Hemispheric specialization for emotional expression, 
Neuropsychiatry, Neuropsychology, and Behavioral Neurology, 6(3), 143-148; 
Silberman & Weingartner, 1986, Hemispheric lateralization of functions related
to emotion, Brain and Cognition, 5, 322-353], functions which presumably 
preceded language, and since language is predominantly a pro-social and 
positive activity, the left side was appropriate (closer to those affects) and
perhaps also more available for language processing.  But thats mostly just a
guess...   


                                  david




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