Beyond that, if there are genetic effects we would expect to see them more strongly in race comparisons than economic status comparisons.
I strongly disagree. The relationship between economic status and intelligence is maintained by strong feedback effects. Intelligent people tend to move to higher economic status, and then mostly pass on those genes for intelligence to offspring. But then, if the offspring were unlucky enough to not get the genes, then they will tend to slide out of that economic status class.
The genetic aspect of the relationship between race and intelligence, if it exists at all, is something of a historical accident. There may be a degree of stability to the relationship, but there is no active feedback loop maintaining it. People do not slide from one racial grouping to another simply because they are born with more or less than the expected amount of intelligence.
Notice that I am not disputing your research claim regarding the degree to which race and economics serve as predictors of measured intelligence. I only dispute the validity of your intuitions regarding what “we would expect to see”.
You put together a strong argument. I think that this will depend on which genes we examine; if there is some intelligence-boosting gene that most Xs have and most Ys do not, then the effect of that gene will be more noticeable when we do race comparisons than economic status comparisons. However, intragroup variability is higher than intergroup variability, which suggests that for every intelligence-boosting gene like that there should be at least three which aren’t strongly associated with race, and if we accounted for all the genes then the intelligence-economic status connection would likely be stronger than the intelligence-race connection (though I have insufficient data to conclude it would be stronger).
I was thinking about the first kind of genetic effects only, since they seem easier to find and study than the second, but you are right to question that choice.
I think we are in rough agreement, though I think you stated this backwards:
However, intergroup variability is higher than intragroup variability
Actually, and empirically, variability within a group is relatively high and variation between groups rather low. (More technically, group membership explains only a small fraction of the total variance.) And you seem to understand this below, with your estimate that three out of four genes bearing on intelligence will not be closely correlated with race.
Thanks! I did, fixed. I should also mention that I’m being loose by assuming all genes that impact intelligence do so by roughly the same amount, which is obviously not true.
I strongly disagree. The relationship between economic status and intelligence is maintained by strong feedback effects. Intelligent people tend to move to higher economic status, and then mostly pass on those genes for intelligence to offspring. But then, if the offspring were unlucky enough to not get the genes, then they will tend to slide out of that economic status class.
The genetic aspect of the relationship between race and intelligence, if it exists at all, is something of a historical accident. There may be a degree of stability to the relationship, but there is no active feedback loop maintaining it. People do not slide from one racial grouping to another simply because they are born with more or less than the expected amount of intelligence.
Notice that I am not disputing your research claim regarding the degree to which race and economics serve as predictors of measured intelligence. I only dispute the validity of your intuitions regarding what “we would expect to see”.
You put together a strong argument. I think that this will depend on which genes we examine; if there is some intelligence-boosting gene that most Xs have and most Ys do not, then the effect of that gene will be more noticeable when we do race comparisons than economic status comparisons. However, intragroup variability is higher than intergroup variability, which suggests that for every intelligence-boosting gene like that there should be at least three which aren’t strongly associated with race, and if we accounted for all the genes then the intelligence-economic status connection would likely be stronger than the intelligence-race connection (though I have insufficient data to conclude it would be stronger).
I was thinking about the first kind of genetic effects only, since they seem easier to find and study than the second, but you are right to question that choice.
I think we are in rough agreement, though I think you stated this backwards:
Actually, and empirically, variability within a group is relatively high and variation between groups rather low. (More technically, group membership explains only a small fraction of the total variance.) And you seem to understand this below, with your estimate that three out of four genes bearing on intelligence will not be closely correlated with race.
Thanks! I did, fixed. I should also mention that I’m being loose by assuming all genes that impact intelligence do so by roughly the same amount, which is obviously not true.