Genetic clustering

Wilhelm

Wilhelm

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What do you think about genetic clustering (alleles, microsatellites,etc) ??
What can they tell us ?
Do you think we can determine race or ethnicity by genetic clustering ?

Here is what a study says :
"We have shown a nearly perfect correspondence between genetic cluster and SIRE for major ethnic groups living in the United States, with a discrepancy rate of only 0.14%."

""It is not true, as Nature claimed, that 'two random individuals from any one group are almost as different as any two random individuals from the entire world'" and Risch et al. (2002) state "Two Caucasians are more similar to each other genetically than a Caucasian and an Asian." "


Genetic clusters study :
structurescience.jpg


A majority green means European, a majority red is African, etc..


Other genetic clustering : There is homogeinity between Europeans, while Levants (American Ashekanazi, Druze, Palestinians,etc) are apart.

jew1x.jpg
 
It's interesting, but they are only using a few carefully selected alleles. So it is not really representative of the actual genetic diversity. Different alleles would give a very different pictures. That's why each study shows a new pattern of clustering - occasionally contradictory. You can find other graphs like that on Dienekes' blog.

"It is not true, as Nature claimed, that 'two random individuals from any one group are almost as different as any two random individuals from the entire world'" and Risch et al. (2002) state "Two Caucasians are more similar to each other genetically than a Caucasian and an Asian."
Click to expand...

This is quite obvious. Although some alleles can be found across all ethnic groups, many are limited to some continents, regions or ethnicities. For example, all blood types can be found all over the world (frequencies for each type obviously vary by region), while the allele for a disease like Hemochromatosis is limited to people of northern European descent. Some SNP have no known physiological or medical effect, but can be used to determine ethnic groups because they are limited to some specific populations. Overall, there are probably more allele variants that are shared by all humanity, but those specific to some ethnicities or families are nevertheless numerous enough to categorise humans in groups.
 
Maciamo said:
It's interesting, but they are only using a few carefully selected alleles. So it is not really representative of the actual genetic diversity. Different alleles would give a very different pictures. That's why each study shows a new pattern of clustering - occasionally contradictory. You can find other graphs like that on Dienekes' blog.



This is quite obvious. Although some alleles can be found across all ethnic groups, many are limited to some continents, regions or ethnicities. For example, all blood types can be found all over the world (frequencies for each type obviously vary by region), while the allele for a disease like Hemochromatosis is limited to people of northern European descent. Some SNP have no known physiological or medical effect, but can be used to determine ethnic groups because they are limited to some specific populations. Overall, there are probably more allele variants that are shared by all humanity, but those specific to some ethnicities or families are nevertheless numerous enough to categorise humans in groups.
Click to expand...

I agree, this type of study provides a rather limited picture...
 
In any case, these studies are outdated. There are several studies spanning 2007 through 2009 that are more refined. I'll post the information once I confirm the appropriate references.
 
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