From: Brett Paatsch (paatschb@ocean.com.au)
Date: Sat Jan 04 2003 - 18:17:48 MST
Gina wrote:
> Brett wrote:
> >IE. Racial purity is in most contexts a nonsense. But if
> >everyone from Africa is black and everyone from Sweden
> >is white (obvious differences - of no importance to me), then
> >perhaps there are differences in populations that are of interest.
> >Eg. Why do some "races" seem to be more susceptible to sickle
> >cell anaemia? Or why do some "races" seem to do better in
> >Olympic swimming whilst others do better in the sprint.
>
> It's not really that the race is more susceptible to sickle cell anemia,
"Race" is tricky to define. Many people would claim they know it when
they see it. And it more or less matters (or doesn't) to them. Not all
would have the same thing in mind when they talk about race and this
is part of the problem.
One of the books I quite enjoyed reading was Brian Sykes "Seven
Daughters of Eve". Sykes uses mitochondrial DNA (or rather vary
small changes to the mitochondrial DNA) which is passed through
the maternal line to produce a maternal family tree of "Europeans".
He thinks he can trace all people of European decent back to seven
particular women, the farthest back being 45,000 years ago.
Jump across to Africa and the ancestral mothers go back much further.
Populations and "racial" groups have been mixing to varying extents
throughout history and I find the idea that we may be able to increasing
trace our geneologies back way before recorded history using the
mitochonrial DNA from the maternal line and they Y chromosome from
the paternal line fascinating. We are likely to find that most of us,
indeed
all of us, will turn out scientifically, to be "family" in the broadest
sense of
the word. That notion might make for a nice extropic meme.
Of course, and this is particularly, pleasing this is going to make those
who are blatantly and obnoxiously racist have to come to terms with in
many cases some surprising facts about their own relatively recent
geneology. Many wll find for instance that at some time in the last thousand
years they may have had an ancestor in exactly that nearby region that
thing they most despise. People will find out (possiblty) that hating the
enemy bizarrely turns out to be akin to hating oneself.
There is however legitimate and more pressing reasons for studying
population genetics. Its hard, now ethically, to justify making small
genetic changes in the germline deliberately to see the differences that
result and the advantages that are conferred in the phenotypes exspressed so
doing
a bit of geneological archeology can be a good way of finding out about
what genetic diseases may be caused. You start with an obvious phenotype
and work back to see if there is a genotype difference (considering say
the people of Iceland) and then maybe you get an understanding of how
the genes influence different. One you know more about the genes that
cause disease there are a variety of approaches you can take to devising
therapies for those that suffer from genetic diseases to giving parents who
may have say the genes for haemophilia the choice as to whether to have
daughters rather than sons.
> it's a defese created due to the factors of the environment, which is now
> genetic. The sickle cell gene provides some protection against malaria. So
> in areas where malaria is common, evolution decided the protection it
> provides against malaria offsets the damage done my sickle cell anemia.
Yes it is genetic mechanisms not the superficially obvious local population
differences that tend to confer advantages for particular environments. But
the superficially obvious population differences can give some indications
of
where to look for promising sets of genes.
As you say trading environments cause genes that are trade off
susceptibility for malaria against susceptibility for anemia. It turns out
to be the same gene.
But its a useful insight (for therapies) to know what the gene is. And the
study
of populations can be a good way of shortlisting the search for beneficial g
enes (bearing in mind) genes aren't good or bad in themselves (the sickle
cell/anemia tradeoff) its still nice to be able to make choices about
treatments and tame some of natures random affliction of unnecessary
suffering if we can..
Regards,
Brett
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