Yes, there are clines, but so what? The population fraction in the clinal region between the major groups is tiny.
I’m not sure that this contradicts what I wrote. I acknowledge that high-resolution genotyping enables one to distinguish geographically distant samples of people. Being able to pull that off does not automatically validate ‘race,’ as in the conventional white people v. yellow people v. brown people v. red people taxonomy.
The distance (e.g. measured by fst) between the continental groups is so large that you would have to stand on your head to not “discover” those as separate clusters.
Or you need only come at the data with an unusual preconception of race, which would affect your analytic approach.
Also, if you take wide-ranging genetic samples across Africa (as opposed to using a handful of samples from one Nigerian city to represent all of Africa, as seems to have been done to derive your picture), it seems to me that you end up getting African clusters that can be as far apart from each other as they are from Europeans.
Another example: check out subdiagram A in this diagram, from a paper that took samples from West and South Africa. The Fulani + Bulala are as far apart from some of the other African samples as they are from the Europeans!
it seems to me that you end up getting African clusters that can be as far apart from each other as they are from Europeans. <
I doubt this would be the case as measured by fst. Note that distance on a principal components graph is not the same as fst: the components might be optimized to separate the clusters of choice (optimize the directions in gene space which show the most variance between the groups). It’s possible in principle that some groups (e.g., pygmies) in Africa have been as effectively separated in gene flow from other Africans as, say, Nigerians and Europeans. More likely, the fst distance between any two groups of Africans is less than the distance from the Yoruba to Europeans or E. Asians. That is what happens when you analyze the (better studied) sub-population structure of, e.g., Europe and Asia. That is, no two groups in E. Asia are anywhere near as far apart as they are collectively from Europeans (and the same for any two European groups vs distance to Asia). That’s just what you’d expect from the historical gene flow patterns, and I’d expect it to apply to Africa as well.
The real question is whether folk notions of ethnicity map onto clusters in gene space. If they do (and they do) it implies different frequency distributions for alleles in the groups. That raises the possibility of statistical group differences. What those differences are remains to be determined.
I agree on the subject of Fst; if you switch from PCA biplots to Fst, that’s going to better emphasize differences due to geographical separation. (But likely still not enough to scientifically confirm a classical racial taxonomy as the one true racial taxonomy. One would still have to decide which samples to use to build one’s Fst matrix and address the issue of how to extract racial categories from the Fst matrix. I’d also anticipate getting caught up in the same sort of issues as the structure program.)
The real question is whether folk notions of ethnicity map onto clusters in gene space.
Folk notions of ethnicity arguably could, because they are far more squishy and pliable than folk notions of race.
If they do (and they do) it implies different frequency distributions for alleles in the groups.
I can’t help feeling that you believe I’m arguing against the validity of race because I think that disproves the possibility of statistical group differences. If so, you can rest easy. I acknowledge the possibility of statistical group differences—it doesn’t live or die by the validity of race. I see (or think I do, anyway) genetic group differences in (relatively) boring traits like skin color and hair color—and if those, why not genetic group differences in drama-provoking traits like IQ, personality or genital size?
OK, so we just differ in nuances of definition. If you prefer ethnicity to race, that’s fine with me.
Well, for whatever it’s worth, I continue to disagree with one of the arguments in the blog entry I mentioned—there is more here than a minor semantic divide.
The usual lame argument is “race doesn’t exist, so how could there be group differences”—but I think neither of us is arguing that side.
So your position is that there are probably allele clusters do to cultural and geographic isolation (and therefore potentially group differences in IQ or personality) your concern is that you don’t think those clusters have been shown to map one to one with our folk racial categories?
Do you think our folk racial categories aren’t the product of observable phenotypes? Do you think those categories at least approximate a valid scientific taxonomy?
My concern (or at least the one that I’m elaborating on in this thread) is that those clusters can be made to map onto folk racial categories, or made to be only partly consistent with folk racial categories, or made to be contradictory to folk racial categories, depending upon how one’s own preconceptions of race color one’s cluster analyses.
Do you think our folk racial categories aren’t the product of observable phenotypes?
No.
Do you think those categories at least approximate a valid scientific taxonomy?
Valid for which scientific purpose? They are likely to be workable categories for a sociologist studying race relations. They are likely to be inadequate categories for a molecular anthropologist studying human genetic variation. Though I expect some molecular anthropologists (and evidently at least one professor of physics) would dispute that.
I’m not sure that this contradicts what I wrote. I acknowledge that high-resolution genotyping enables one to distinguish geographically distant samples of people. Being able to pull that off does not automatically validate ‘race,’ as in the conventional white people v. yellow people v. brown people v. red people taxonomy.
Or you need only come at the data with an unusual preconception of race, which would affect your analytic approach.
Also, if you take wide-ranging genetic samples across Africa (as opposed to using a handful of samples from one Nigerian city to represent all of Africa, as seems to have been done to derive your picture), it seems to me that you end up getting African clusters that can be as far apart from each other as they are from Europeans.
Another example: check out subdiagram A in this diagram, from a paper that took samples from West and South Africa. The Fulani + Bulala are as far apart from some of the other African samples as they are from the Europeans!
I doubt this would be the case as measured by fst. Note that distance on a principal components graph is not the same as fst: the components might be optimized to separate the clusters of choice (optimize the directions in gene space which show the most variance between the groups). It’s possible in principle that some groups (e.g., pygmies) in Africa have been as effectively separated in gene flow from other Africans as, say, Nigerians and Europeans. More likely, the fst distance between any two groups of Africans is less than the distance from the Yoruba to Europeans or E. Asians. That is what happens when you analyze the (better studied) sub-population structure of, e.g., Europe and Asia. That is, no two groups in E. Asia are anywhere near as far apart as they are collectively from Europeans (and the same for any two European groups vs distance to Asia). That’s just what you’d expect from the historical gene flow patterns, and I’d expect it to apply to Africa as well.
The real question is whether folk notions of ethnicity map onto clusters in gene space. If they do (and they do) it implies different frequency distributions for alleles in the groups. That raises the possibility of statistical group differences. What those differences are remains to be determined.
I agree on the subject of Fst; if you switch from PCA biplots to Fst, that’s going to better emphasize differences due to geographical separation. (But likely still not enough to scientifically confirm a classical racial taxonomy as the one true racial taxonomy. One would still have to decide which samples to use to build one’s Fst matrix and address the issue of how to extract racial categories from the Fst matrix. I’d also anticipate getting caught up in the same sort of issues as the structure program.)
Folk notions of ethnicity arguably could, because they are far more squishy and pliable than folk notions of race.
I can’t help feeling that you believe I’m arguing against the validity of race because I think that disproves the possibility of statistical group differences. If so, you can rest easy. I acknowledge the possibility of statistical group differences—it doesn’t live or die by the validity of race. I see (or think I do, anyway) genetic group differences in (relatively) boring traits like skin color and hair color—and if those, why not genetic group differences in drama-provoking traits like IQ, personality or genital size?
OK, so we just differ in nuances of definition. If you prefer ethnicity to race, that’s fine with me.
The usual lame argument is “race doesn’t exist, so how could there be group differences”—but I think neither of us is arguing that side.
Well, for whatever it’s worth, I continue to disagree with one of the arguments in the blog entry I mentioned—there is more here than a minor semantic divide.
Correct.
So your position is that there are probably allele clusters do to cultural and geographic isolation (and therefore potentially group differences in IQ or personality) your concern is that you don’t think those clusters have been shown to map one to one with our folk racial categories?
Do you think our folk racial categories aren’t the product of observable phenotypes? Do you think those categories at least approximate a valid scientific taxonomy?
My concern (or at least the one that I’m elaborating on in this thread) is that those clusters can be made to map onto folk racial categories, or made to be only partly consistent with folk racial categories, or made to be contradictory to folk racial categories, depending upon how one’s own preconceptions of race color one’s cluster analyses.
No.
Valid for which scientific purpose? They are likely to be workable categories for a sociologist studying race relations. They are likely to be inadequate categories for a molecular anthropologist studying human genetic variation. Though I expect some molecular anthropologists (and evidently at least one professor of physics) would dispute that.