Validity of national skin color-IQ
We previously reported that a measure of school achievement built from national test scores has a nearly perfect correlation with national IQ (at least in the range of scores tested). Subsequently, Lynn et al. (in press) published a very similar analysis:
This paper examines the relationship of the national IQs reported by Lynn & Vanhanen (2002, 2006) to national achievement in mathematics and science among 8th graders in 67 countries. The correlation between the two is 0.92 and is interpreted as establishing the validity of the national IQs. The correlation is so high that national IQs and educational achievement appear to be measures of the same construct. National differences in educational achievement are greater than differences in IQ, suggesting an amplifier effect such that national differences in IQs amplify differences in educational achievement. Controlling for national differences in IQ, slight inverse relationships of educational achievement are observed with political freedom, subjective well-being, income inequality, and GDP. However, public expenditure on education (as % of GDP) was not a significant predictor of differences in educational achievement.
The IQ’s Corner blog has an interesting note about forthcoming commentary.
On a related note, recall that Templer & Arikawa (2006) reported a near perfect environmental correlation between national skin color and national IQ for old-world countries. An unfortunately confused commentary by Hunt & Sternberg accompanied the publication. They wrote: “We argue that the report by Templer and Arikawa contains misleading conclusions and is based upon faulty collection and analysis of data. The report fails to hold up for quality of data, statistical analysis, and the logic of science.” The criticisms by Hunt & Sternberg are based largely on a misreading of Templer & Arikawa’s methods, particularly the method for deriving national skin color values.
A paper published in 2000 by Jablonski & Chaplin (“The evolution of human skin coloration”) can more directly address these criticisms. Jablonski & Chaplin published a table of skin color reflectance values from many old world populations (Table 6, also see the appendix). I very crudely averaged values from the same country to make a new measure of national skin color. This measure of national skin color correlates with the skin color index of Templer & Arikawa at r=-.91 (the negative is not important here). The reflectance measure of skin color correlates with national IQ at r=.87. The school achievement measure of Lynn et al. correlates r=-.79 with the skin color index of Templer & Arikawa and r=.75 with the skin color reflectance values crudely averaged from Jablonski & Chaplin. Thus, the skin color values derived by Templer & Arikawa are well validated by an external data source and the national IQ-skin color relationship is found to be robust across two measures of national IQ and two measures of national skin color.
Note that there are substantially more missing values in the school achievement and skin reflectance data sets (no imputation of missing values) with missing values skewed towards lower values of national IQ/school achievement and darker skin colors. Also note that the blind averaging use on the skin reflectance data most likely attenuates the correlations.
Templer & Arikawa had two abstracts at the 2006 ISIR conference, which provide additional support for the validity of the measures and their relationships:
source
Correlations of Skin Color and Continent with IQ
Donald I. Templer & Hiroko Arikawa
The present study determined (1) the correlations between skin color and IQ across the countries of three different continents; and (2) the correlations of both skin color and continent in the three pair combinations with the three continents. The product-moment correlations between IQ and skin color were -.86 across the 48 African countries, -.55 across the 48 Asian countries, and -.63 across the European countries. When the 96 countries of Africa and Asia were combined skin color correlated -.86 and continent correlated .75 with IQ. The respective correlations were -.97 and .89 across the 81 countries of Asia and Europe, and -.71 and .54 across the 81 countries of Europe and Asia. In multiple regression continent yielded minimal increment to skin color in predicting IQ. 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. The present findings, combined with previous research relating skin color and IQ (Templer & Arikawa, 2006a; 2006b), indicate that skin color is a robust correlate of IQ in an international perspective.
Empirical Support for Rushton’s K Differential Theory
Donald I. Templer & Hiroko Arikawa
The purpose of the present study was to empirically substantiate Rushton’s Differential K Theory that purports that groups of persons with K (in contrast to r) characteristics have a life history and reproductive strategy that includes higher intelligence, less reproduction, less sexual activity, better care of offspring, lower birth rates, greater life expectancy, better impulse control, and greater social organization. The present research intercorrelated national mean IQ, infant mortality, HIV/AIDS rates, birth rates, prevalence rates, and life expectancy in 129 countries in Africa, Asia and Europe. All of the correlations were substantial and in the expected direction. Also supportive of Rushton’s theory is that there was only one factor which accounted for 75% of the variance and was labeled “K-r continuum.” All five variables were correlated with an economic variable (per capita income) and a biological variable (skin color, which correlated highly with intelligence in previous research). Skin color correlated more highly with all five variables than per capita income so as to support the contention of Rushton that this continuum is biologically based. Factor analysis with all seven variables yielded one factor that accounted for 73% of the variance.
Jason Malloy adds: Templer & Arikawa’s research follows Lynn and Rushton in arguing that cold temperatures were a significant force in the evolution of human race differences in intelligence. I have stated some problems I find with this hypothesis here, although it is also largely consistent with the geographic distribution of global populations by IQ. A recent analysis by blogger Audacious Epigone adds yet another revealing data point to this association.
Latitude (and hence colder climate) is associated with IQ not only cross-nationally (.67) but within the US as well. AE found a correlation of .70 between his measure of state IQ and the latitude of the most populous city in each of the 50 states. Furthermore intelligence is associated with latitude equally for both US whites and blacks (.52 and .51).
It’s not immediately apparent if and how this association is genetic or environmental. Either way it seems fair to seriously consider that global warming will provide yet another detrimental negative pressure on the intelligence of human populations in the coming decades.
Labels: general intelligence, national IQ, Pigmentation, skin color
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:
A2007_3Ai_3A1_3Ap_3A7-11.htm
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_3
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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.
The results of Templer & Arikawa are not surprising. The observation of a high correlation (r = 0.89) betweeen skin reflectance and IQ had first been published by me in 2004, as an aside in a little known paper entitled Talent, character, and the dimensions of national culture, published in the Mankind Quarterly 45: 123-168 (Table 1). The results were based on the 2000 Jablonski & Chaplin paper, with a lot of extrapolation for countries that had no information for skin reflectance. Templer & Arikawa did not know about this earlier work when they published their paper in Intelligence. Templer & Arikawa used a different source of the skin color data, an old map from an anthropology textbook. In their reply in the same issue of Intelligence, Hunt & Sternberg dismissed this data source as unacceptable. They obviously were unaware that I had found virtually the same result with a different data source. The reason for this striking result is of course that the African countries consistently have both the darkest skin color and the lowest IQs. If the African countries are omitted from the analysis, the relationship of IQ with skin color is no stronger than its relationship with GDP and other development indicators. Therefore we need to be cautious with our interpretations. There is a phenomenon called spatial autocorrelation that inflates correlations and significance levels when neighboring countries share similar traits. The relationship between IQ and skin color is suggestive, but not nearly conclusive.