Human Genetic Diversity

Guillermo Barron gbarron at gpu.srv.ualberta.ca
Mon Aug 4 10:45:27 EST 1997


I wondered if anyone on this group could answer a question from a
neophyte (graduate student in philosophy) whose understanding of
genetics does not penetrate much beyond reading Dawkins' *Blind
Watchmaker* and Dennett's *Darwin's Dangerous Idea?*

   A recent artcicle in Canada's  *Globe and Mail* argued against incest
on the grounds that incestuous reproduction decreases genetic diversity
which many people count as a key factor in enhancing the survival of the
human species. The sociobiologist E.O. Wilson, for example, calls
genetic diversity a "cardinal value (1978)."

Now I don't know if in fact unrestrained incestuous reproduction would
occur frequently enough to affect the human gene pool in any meaningful
way.  But it does seem clear that heterogeneous human mating (if I can
call it that) *is* widespread. Up until very recently most humans mated
not only within their own race but within relatively narrow tribal and
geographical limits. This has of course changed quite radically within
the last century or so with the advent of global migration.   My
question is: does mating between genetically different populations
increase or decrease diversity?   In other words, would Laplanders
mating with Yanomani, and Tibetans mating with Cherokees increase or
decrease human genetic diversity?

Note that, no matter how the genetic variation argument runs,  I don't
in any way endorse any eugenic policies or anti-miscegenation laws  (nor
do I wish to garner anyone's support for any dubious political ends!). 
I'm simply not sure what humans ought to do to improve human genetic
diversity, or if it's even something we should worry about.  Any
comments or references to helpful sources (comprehensible to a
layperson) would be most appreciated.  Since I don't regularly watch
this group, a direct e-mail reply woudl be greatly appreciated.

Thank you.

Guillermo Barron



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