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From: krista@ihlpa.ATT.COM (K.J.Anderson)
Newsgroups: sci.bio
Subject: Bushmen
Message-ID: <4505@ihlpa.ATT.COM>
Date: Wed, 1-Jul-87 18:06:12 EDT
Article-I.D.: ihlpa.4505
Posted: Wed Jul  1 18:06:12 1987
Date-Received: Sat, 4-Jul-87 03:27:05 EDT
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 79

Well, I was quite surprised to read a posting about Kalahari Bushmen
which claimed that the Bushmen are genetically different from other
people in the following ways:

a) A camel like hump adapatation, for water storage,
b) Sterile offspring from marriages to other groups,
c) Over 50% of the population has number of chromosomes not = 46.

Because I've read several books about anthropology and never heard
of such a thing, I went to the library to check it out. Well, I
suspect that the original poster's memory played tricks on him!  It
happens to everyone sometimes.  Nowhere could I find any mention of
chromosome differences among so called "races", and I did skim
through several books including _Encyclopedia Britannica_. 
However, I did find some quotes that the memories of which could be
twisted by the ravages of time. :-)

a) "[Bushmen]...are extremely hardy: the fat on the women's buttocks
and thighs is a reserve for lean times, rather like a camel's hump. 
Noone is sure where they came from and their Mongol strain is a
mystery." [1]  This extra fat deposit is called steatopygy.  But all
women have fat on their buttocks and thighs!  And everybody's fat
cells function as storage. It is a matter of degree, not a
difference in the genetic map.  As for the mystery, the authors mean
it is a historical mystery, not a biological one.

b) "There is another possible reason why families are small. 
According to the Bushmen themselves their women are naturally
sterile during the dry season." [1]  Here again, note that cessation
of menses is not uncommon among female professional athletes, or
under other circumstances where the body is unprepared for
pregnancy, regardless of the woman's ethnic background.  Two of the
books mentioned intermarriage with other groups (besides Hottentots)
but made no mention of any problems.

c) "Were we to build a human family tree on DNA sequences alone, it
would be branchless.  No significant differences between our races
could be seen.  All of us, from Eskimo to Australian aborigine would
be genetically as alike as peas, and almost as closely related to
chimpanzees as we are to one another." [2]  Now, this same resource
goes on to discuss "... distances between the chemical components in
the codons in the blood of three racial samples...", and does find
significant differences in the presence or absence of subsets of
thirty *proteins*, not chromosomes, so maybe that's what the
original poster was recalling. 
   There are also studies of blood types and factors, but it is hard
to make conclusions because we cannot determine whether a certain
population never had a particular gene, or whether it once had the
gene, but it was bred out.  Coon, in [3] discusses blood types. 
Even in blood studies, we must realize that presence or absence of a
factor does not suggest a *structural* difference in the chromosomes.

   Anyway, my point is that while there are physiological variations
that may be geographically grouped, there is no evidence of
subspeciation.  Indeed, Montegu criticizes Coon for exaggerating the
significance of regional variations.  Montegu thinks that the
concept of race is a social idea rather than biological reality. [4]
   In _The Monkey Puzzle_, the authors agree with that opinion.  Some
molecular DNA studies have shown no real distinction among the so
called races.  The genetic variations among individuals of one population
are about 6%.  The genetic variations of the means among different
populations are, uh, 6-7%.  In other words, the physical adaptations
that we see in different parts of the world are still within the
limits of normal species variation. [5]
   There still are puzzles, however, including a group of people
whose mitochondrial DNA differs from the rest.  Because mitochondria
seem to be neutral, they provide a measure of historical mating
patterns.  Most people's mitochondrial DNA shows that they have
shared the same gene pool for 40,000 years.  The other group's
mitochondrial DNA puts them in an older gene pool - 100,000 years. [5]

References:
1) _Peoples of the Earth_, Volume 9, published by Grolier.
2) _Racial Adaptations_, by Carlton Coon.
3) _The Living Races of Man_, by Carlton Coon.
4) _The Fallacy of Race_, by Ashley Montegu.
5) _The Monkey Puzzle_, by John Gribben and Jeremy Cherfas
-- 
ihnp4!ihlpa!krista - I can't help it, I'm just a baby ape.