this is just reiterating the correlation between race & IQ found by L & V, right? (as variation in skin color tracks variation in race)

Economists are paying some attention to this:

Rati Ram has a new paper in Economics Letters that throws national average IQ into some cross-country growth regressions--the workhorse of empirical growth research--and finds that Lynn and Vanhanen's IQ measure is a remarkably robust predictor of long-term growth.

I can't find a free version, but the link is here for subscribers is here:

http://econpapers.repec.org/article/eeeecolet/ v_3A94_3Ay_3A2007_3Ai_3A1_3Ap_3A7-11.htm
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IQ and economic growth: Further augmentation of Mankiw–Romer–Weil model

Rati Ram, Illinois State University

Abstract:

[Nobel Laureate] Solow's growth model is further augmented to include IQ in addition to proxies for education and health. The estimates indicate that [inclusion of the] IQ variable greatly erodes the size and significance of education and health parameters and dominates even a measure of institutional quality.
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By my count, this is the fourth published article in the economics literature using Lynn and Vanhanen's data--3 pro, 1 con.

Z, i purposefully left out any discussion of causal relationships in order to focus just on the question of validity.

but T&A said this:

In an earlier study (Templer & Arikawa, 2006a) skin color correlated more highly with IQ than racial category, but racial category yielded greater increments in multiple regression than did continent in the present study.

it's hard to say with any certainty because IQ, skin color, race, health measures, and education measures are so strongly intercorrelated at the national level.

i purposefully left out any discussion of causal relationships in order to focus just on the question of validity.

sure, but you knew that someone was going to bring it up! ;-) we are starting to get a grip on skin color genes in regards to between group variation (even within group). most of the variance is due to loci of large effect. is the consensus still that g is summation of small effect?

i doubt very much that any of the relationship is due to pleiotropy (but i guess i can't rule that out on first principles).

sure, i just wanted to get that out there though.

within population variation in g is likely due to a many loci of small effect, but i don't know if there's enough data to say what a genetic cause of between population variation would have to look like.

When animals are domesticated, they tend to develop certain aesthetic traits (e.g., floppier ears) as they are selected for certain behaviors. So, it's not impossible that fairer skin is a something of a side effect for selection for something else. That there were two separate mutations for fairer color -- East Eurasia vs. West Eurasia -- could be useful in investigating this.

It would be interesting to investigate skin color differences within the giga-countries, India and China. My ill-informed guess is that there is less correlation between fairness of skin and IQ within those two countries than across country lines.

within population variation in g is likely due to a many loci of small effect, but i don't know if there's enough data to say what a genetic cause of between population variation would have to look like.

SLC24A5 is disjoint between africans & europeans. there are certainly populations (algeria? the tuareg?) where it need not be fixed. if the two alleles are segregating in a population and there is a correlate between it and g wouldn't it show up as a QTL for IQ? i can think of one population where it has to be segregating: black americans (who are 15-25% genetically european and so should have the loss of function variant of SLC24A5 at that frequency). there should be many families which exhibit variation in who carries which allele of SLC24A5.

It would be interesting to investigate skin color differences within the giga-countries, India and China. My ill-informed guess is that there is less correlation between fairness of skin and IQ within those two countries than across country lines.

i don't know of any perception/data which shows that darker-skinned south chinese and japanese are less intelligent than their lighter-skinned compatriots, though skin color & SES do correlate somewhat in japan (i believe that the burakumin/eta are darker while the descendents of the old tokugawa era nobility are lighter). in india within the nation there certainly isn't a correlation in the direction you'd want i would think, though within ethnic groups probably because of the correlation between caste & color, etc.

if the two alleles are segregating in a population and there is a correlate between it and g wouldn't it show up as a QTL for IQ?

yes

black americans ... caste & color

yeah, this all comes back to the admixture/MALD question. the correlation at a national level probably exists because of differences in average admixture having a corresponding effect on skin color and IQ.

T&A conceived of their study as a test of Rushton's hypothesis, but aside from establishing the truth of the correlation, I don't see it helping much with causal theories.

Maybe this is completely offtopic, but there are lots of dark brown Indians here who are plenty smart.

Maybe this is completely offtopic, but there are lots of dark brown Indians here who are plenty smart.

that's what lwka wuz getting @ re: pleiotropy.

-a medium brown american

Raz - I recall Lynn's data showed southern Chinese to have higher IQ than northern Chinese, but I recall that his southern Chinese sample came (largely?) from Hong Kong and therefore could not be taken as representative of southern China. It is not even clear whether the Chinese sampled in Hong Kong were all of southern Chinese origin - most likely they were not, even if they were Cantonese speakers (Cantonese is the lingua franca in Hong Kong). Consequently I don't think anything useful can be concluded from his Chinese data in relation to correlation between skin colour (reflectance?) and IQ.

Is the difference in national IQ based on national color, or on IQ test design?

I recall Lynn's data showed southern Chinese to have higher IQ than northern Chinese, but I recall that his southern Chinese sample came (largely?) from Hong Kong and therefore could not be taken as representative of southern China. It is not even clear whether the Chinese sampled in Hong Kong were all of southern Chinese origin - most likely they were not, even if they were Cantonese speakers (Cantonese is the lingua franca in Hong Kong). Consequently I don't think anything useful can be concluded from his Chinese data in relation to correlation between skin colour (reflectance?) and IQ.

*shrug*

the vast majority of the overseas chinese are south chinese (USA were traditionally cantonese, southeast asia generally from fujian).

Sure, but Hong Kong does not conform to that general migration pattern - the majority in Hong Kong originate from Guangdong Province, but there are very substantial minorities originating from Shanghai and parts further north. Also, even if they all originated in Guangdong Province, they could not be taken to be fully representative because of environmental and other differences. The IQ difference between north and south found by Lynn is easily within a range that could all be explained by environmental differences, e.g. access to better schooling and generally greater affluence.

With the recent generations in Hong Kong there has also been a breaking down of cultural and geographical barriers and a lot more mixing between people from different regions in China - northerners marrying southerners etc.

And Guangdong Province is obviously only a part of southern China - it's a big country.

Actually, I thought it was a bit naff of Lynn to report Hong Kong data as 'southern China'.

sang, yes about hong kong. my point though is that we have psychometric data from the descendents of cantonese and japanese laborers in the USA. and in singapore we have the fujianese descended groups (as well as the rest of southeast asia). the numbers i saw from hong kong were high, but not out of the range of those from overseas chinese communities with origins on guangdong and fujian. and, the SES origins of chinese in the USA before the current post-65 migration were not high from what i know. also, 90% of taiwanese are derived from fujian stock.

in the data set Lynn reports in RDiI, there's an upward trend in E.A. IQ scores in the U.S.

Yes, descendants of. I'm just saying that the north-south difference reported by Lynn, such as it was, could be explained by environmental factors - Chinese migrants from whatever SES have tended to distinguish themselves by doing well financially and investing a lot in their kids' education, and if nutritional differences have an effect, that could be a relatively big influence.

If he really had sampled representatively in southern and northern China, fine. If he sampled the descendants of northern Chinese who had migrated, also fine, but I couldn't find that out from his papers.

If the within-country difference is real and due to genetics, then it contradicts the general correlation between IQ and skin reflectance, but I'm sceptical.

lwka - Yes, I'm not surprised by that at all.

I've added a comment to the post.