From: Scott Chase (ecphoric@hotmail.com)
Date: Mon 04 Aug 2003 - 19:14:50 GMT
I have previously cited some genetic hocus pocus I have found within the
pages of Richard Klein and Blake Edgar's book _The Dawn of Human Culture_.
In outlining their bold theory for a genetic mutation that "promoted the
fully modern human brain" (Klein and Edgar, page 270) circa 50,000 years ago
they note a decoupling of anatomical and behavioral change, which in itself
isn't too contentious IMO as it points to the importance of cultural
evolution as it may have eventually started taking off on a trajectory of
its own. Memeticists might look at this as the dawn of memes as a cultural
force. This decoupling is assumed to have a basis upon a "neural change"
which itself would have a basis upon a "fortuitous mutation". This "neural
change" is related by Klein and Edgar to "rapidly spoken phonemic language"
(page 271). I would grant that language has been a key ingredient in modern
human evolution and must be integral to cultural evolution (innovations and
the like). The neural changes involved in the evolution of language were
probably multiple and cumulative.
The most contentious part of Klein and Edgar's theory is when they try to
buttress their claims for *a* (note the emphasis) fortuitous mutuation via
citation of work by a "team of geneticists led by Cecilia Lai of Oxford
University" (page 271). They quote from the article (Nature, 4 October 2001)
that a single gene is probably "involved in the developmental process that
culminates in speech and language." (Lai et al quoted by Klein and Edgar,
with the qualifier "probably" added by the latter). I haven't read the
original article so I'm going second hand from the treatment in this book. I
grant for the sake of argument here that this supposed gene may be involved
in linguistic ontogeny. Defects are associated with linguistic deficits. In
other words a mutation has been found that involves loss of function. Klein
and Edgar go on to use this deficit as evidence for the possibility of a
single mutation being reponsible for the emergence of language. What? No
other genes would be involved? A single mutation could give us language *de
novo*?
This scenario prepared me for the comic relief that Jonathan Marks provides
in his chapter on behavioral genetics in his book _What it Means to be 98%
Chimpanzee_. The gist of Marks's sarcastic send up is that "(i)t is very
easy to confuse pathology for normalcy, and vice versa. You don't
necessarily learn about the normal function of an object from its
breakdown." (Marks, page 106). This chapter should be required reading for
sociobiology enthusiasts. I might get a little perturbed by Marks's earlier
take on human/chimp relations and classification, but he endears himself to
me in this chapter, especially taking the wind out of sociobiological sails
for aggression and gay genes. His send ups of these revealed truths are a
thing of beauty.
Getting back to Klein and Edgar's quasi-saltational linguistic hopeful
monster, in short, how can a single defect associated with speech pathology
be trumpeted as evidence of a gene for normal function (ie a gene for
language) and on top of this how can this pathology be trumpeted as a
possible case of a single mutation facilitating the advent of language and
the modern human brain 50,000 years ago? There's holes wide enough to drive
a tractor trailer through, if I'm not mistaken.
refs:
Klein R and Edgar B. 2002. The Dawn of Human Culture. John Wiley & Sons,
Inc. New York
Marks J. 2002. What it Means to be 98% Chimpanzee. University of California
Press. Berkeley
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