April 30, 2017

Race and IQ: Mixed Populations Part 1

One argument for heredetarianism is that, around the world, mixed-race populations have IQs, or other standardized test scores, that are intermediate between the two races they are a mixture of.

Of course it’s messy, and we’re relying on subjective classification, but subjective classification is usually the same as best-fit genetic cluster anyway, and of course some populations of blacks could be genetically more intelligent than other populations, just as some populations of whites can be more intelligent than other populations of whites, and even some populations of blacks can be more intelligent than some populations of whites.

That’s why we look at all the data we can get. If you know of a study not here, leave a comment (I get notified of Disqus comments) and I will try to add it as soon as I can.

Minnesota Transracial (MTAS) 1992:

The Minnesota Transracial Adoption Study was a study done by Sandra Scarr which tracked white, black mulatto and an “Asian/Indian” sample of adoptees to white families. The “Asian / Indian” sample is not meaningful since we don’t know how many of each are in that sample. These were the scores:

Group IQ age 7 IQ age 17 Number
Biological White 116.7 109.4 143
Adopted White 111.5 105.6 25
Adopted Mulatto 109 98.5 29
Adopted Black 96.8 89.4 101
Adopted Asian/Indian 99.9 96.2 21

Scarr noted that there was no difference in scores between mulattoes that looked and considered themselves “black” and those that looked lighter. Unfortunately she didn’t give the numbers for that.

Scarr initially tried to spin her data to support an environmental hypothesis, but eventually said that the data could be used to support either side:

The test performance of the Black/Black adoptees [in the study] was not different from that of ordinary Black children reared by their own families in the same area of the country. My colleagues and I reported the data accurately and as fully as possible, and then tried to make the results palatable to environmentally committed colleagues. In retrospect, this was a mistake. The results of the transracial adoption study can be used to support either a genetic difference hypothesis or an environmental difference one (because the children have visible African ancestry). We should have been agnostic on the conclusions”

The study obviously supports the heredetarian position exclusively, or at least hits hard against home environment as an explanation. I have never seen anyone cite MTAS to support an environmentalist case, it is always treated by both sides as a piece of heredetarian evidence to either be touted or minimized.

Scarr has since quit her psychology research and is now a coffee-grower in Hawaii.

Moore 1986:

Elise Moore in 1986 looked at blacks and mulattoes adopted by white parents and black parents. The blacks and mulattoes adopted by white parents had IQs 16 and 10.8 points higher than when they were adopted by white parents. The subjects were tested at age 7.

Race White Parents Number Black Parents Number
Black 118 9 102 17
Mulatto 116.5 14 105.7 6

This study was used to argue that the race IQ gap was partly, if not mostly, explained by white parenting being better. Keep in mind however, that at age 7, the mulattoes in the minnesota transracial adoption study had an IQ of 109, only 2.5 points behind the adopted whites. This is what one would predict since heritability increases with age.

The Moore Adoption Study is interesting in that it shows the blacks and mulattoes having very close scores. Unfortunately it only has a sample size of 46 and no white group to compare the scores to, compared to 319 for the Minnesota Transracial study.

Notwithstanding, Richard Nisbett considers this a superior study to Minnesota Transracial, saying,

A superior adoption study [to MTAS] — and one not discussed by the hereditarians — was carried out at Arizona State University by the psychologist Elsie Moore, who looked at black and mixed-race children adopted by middle-class families, either black or white, and found no difference in I.Q. between the black and mixed-race children.”

Interesting how heredetarians don’t discuss Moore, especially given that the only place I could find non-paywalled breakdown’s of Moore’s data were from heredetarian blogs and descriptions in old papers by Rushton and Jensen.

Owen 1992:

In 1992 K. Owen went to South Africa and tested 1,056 Whites, 1,063 Indians, 778 Coloreds and 1,093 Blacks aged 15 using Standard Progressive Matrices. The results were:

White score Indian score Colored score Black score
Set A 11.46 10.91 10.63 9.6
Set B 10.56 9.94 8.78 6.25
Set C 8.87 8.31 7.16 5.28
Set D 9.04 8.5 7.37 4.93
Set E 5.34 4.33 2.75 1.59
Total 45.27 41.99 36.39 27.65
IQ conversion 100 92.23 78.99 58.31

This scoring is particularly harsh because I’m simply setting the white score to 100, and using the white standard deviation – which is 6.34, to convert each group’s raw scores to IQ. If you used the standard deviations and the mean for for the whole population, everyone would have much higher scores.

Owen shows the ubiquitous result of mulattoes scoring intermediate between blacks and whites. But what is more illustrative is the breakdown of the scores by question:

Larger image here

In each set the questions get harder, and you can see that in the early questions there is almost no racial difference at all. But the more difficult the questions, the more racial disparity there is.

And this is why the magnitude of the gap being “15 points” is not always meaningful. Because if want to spike the test and get blacks scoring the same as whites, just make the test easy. If every question was as easy as the first 6 questions of set A, the black-white gap would be negligible.

If you want to increase the racial gap, make the test hard – but not so hard that everyone is guessing, as Progressive Matrices are multiple choice. Questions like number 52 to 56 would maximize the racial gap if that’s what you wanted to do. Past that and everyone is just guessing and the racial gap goes away.

Codwell 1947:

I could not track down the original paper for this, only the scores reported by Lynn.

Race IQ Number
White 100
Mulatto 91 284
Blacks 87 176

Rowe 2002:

David Rowe in 2002 analyzed Wave 1 the National Longitudinal Survey of Adolescent Health and looked at, among other things, the PVT scores for blacks, mixed and white students. The data was a follows:

Race Verbal IQ Number
Black 93.6 4,271
Mixed 102.5 116
White 105 10,315

Very high score for the mixed, but still fits the “intermediate race, intermediate IQ” generality.

Tizard 1974:

In 1974 Barbara Tizard went to some Caribbean countries and gave some kids aged 3 to 4.5 some IQ tests. Here were the results:

1st Study

Race IQ Number
White 100.5 39
Black 102.35 22
Mixed 102.5 24

2nd Study

Race In Orphanage Number Adopted Number Restored to Mother Number
White 101.2 10 113 17 98.2 9
Mixed 109.3 7 119.9 7 102.2 5
Black 105.6 8 106 1

The obvious problem with this study is that the sample is heavily selected. What it shows is that blacks and mulattoes in caribbean orphanages had higher IQs than whites did at age 4.5. I don’t think any conclusions can be drawn from such a weird study, but I’m putting it up so I’m not accused of “ignoring the data”.

Fernandez 2001:

In 2001 Maria Fernandez looked at the IQs of 10-year olds in Brazil of “Asians”, Whites, Browns (mestizos) and blacks.

Race Raw Score IQ Number
“Asian” 38.5 104.3 186
White 35.5 100 735
Brown 25.2 85.1 718
Black 15.8 71.6 223

These scores take Fernandez’s raw scores, sets the white score to 100 and uses the white standard deviation to give the scores for the other groups.

Claassen 1990:

Classenn looked at 1,561 South African school kids aged 11 to 14. These were their scores by subtest on the “General Scholastic Aptitude Test”:

Race / Language White / English White / Afrikaans Colored / English Colored / Afrikaans
Number 405 341 353 462
Word Analogies 18.55 14.39 14.37 11.86
Word Pairs 15.56 15.36 12.08 10.75
Verbal Reasoning 17.38 16.53 14.81 11.14
Number Problems 16.22 15.23 14.36 10.74
Number Series 18.22 17.61 16.5 13.58
Figure Analogies 18.67 17.83 16.01 12.36
Pattern Completion 17.97 16.89 13.89 10.88
Total 122.57 113.84 102.02 81.31
Non-Verbal 71.08 67.56 60.76 47.56
Verbal 51.49 46.28 41.26 33.75
Total IQ 104.2 100 94.34 84.42
Non-Verbal IQ 102.95 100 94.3 83.23
Verbal IQ 105.82 100 94.39 85.99

IQ conversions set white Afrikaans to 100 and use the overall standard deviation.

Eyferth 1961:

The Eyferth Study” is infamous in these narrow circles as a study used to show that, once free of the racist american environment and/or toxic black culture, blacks have IQs very close to whites.

The study was on bastards born of German women who were raped by US troops during occupation at the end of World War 2, and looked at their IQs.

Blacks in the US Army had the bottom 30% excluded for failing a mental test, which puts the best estimate for the median IQ of US Army blacks in 1945 at 90.77. This is done simply by removing IQs below 77.14 from a black IQ bell curve (which is the bottom 30%), and then calculating the area above 77.14 which takes up 35% of the area under the curve, and that area ends at 90.77.

Here is a visual explanation of what I did so you don’t think I’m doing anything fishy:

(Since this is no longer a normal distribution, but a truncated normal distribution, the median is not the same as the mean. In this case, the mean will be higher. I don’t know how much higher because I don’t know how to find the mean of the section of a normal distribution. But I know I can’t overestimate the black IQ in this sample if I use the median, so I’m using the median.)

In this study, however, “20 to 25 percent” of the “African” rapists were North African. Based on an estimate of Indians in the UK of 93, I we can conservatively estimate their IQ, – or at least their “genotypic IQ” – to be 93.

So then, what would we expect the IQs of the mixed-race bastards to be? Well, assuming the German women have an average IQ of 100, we would expect the illegitimates to have an IQ of 95.66 or 95.61 depending on how many North Africans are in there, which averages to 95.635.

About 3% of white soldiers were rejected for too low IQs, which would raise the white soldier IQ to around 101.

Without any specific knowledge of what the IQs of the rapists are, just going purely off of demographic data and population exclusion, that is what any heredetarian would predict (or pretty close to it).

Now, here is the great Eyferth study that casts aside the heredetarian dogma, compared to what the numbers should be according to heredetarians:

Group Eyferth IQ Heredetarian “Prediction”
White Males 101 100.5
White Females 93 100.5
Mixed Males 97 95.6
Mixed Females 96 95.6

The low white score is entirely a function of the low white female score. Just as a thought experiment, for the heredetarian prediction to match the Eyferth results of 96.5, the IQs of the African rapists – Sub-Saharan and North African combined – would have to be 93, or at least a “genotypic IQ” of 93.

Aside from the weird white female IQ score, Eyferth is more a confirmation of heredetarian predictions than an argument against it.

Richard Nisbett disagrees, however, saying,

Eyferth (1961) examined the IQs of several hundred German children fathered by Black GIs during the post-1945 occupation and compared them with the IQs of children fathered by White GIs. The children of the Black GIs had an average IQ of 96.5. The children of the White GIs had an average IQ of 97. Because the (phenotypic) Black–White gap in the military was similar to that for the U.S. population, these data imply that the Black–White gap in the U.S. population as a whole is not genetic, even in part (Flynn, 1980, pp. 87–88). The results seem particularly telling because it seems highly likely that environmental conditions were inferior for Black children.”How do Rushton and Jensen (2005) treat this study, so telling on the face of it? They give it only two sentences of description and then proceed to critique it on two main grounds. First, 20% to 25% of the “Black” fathers were North African. But one would have to assume preposterously high IQ scores on the part of the North African portion of the Black population to make up for the substantial difference between offspring of Blacks and Whites predicted by their hereditarian theory.”Second, Rushton and Jensen assume that Black soldiers were more rigorously selected than Whites and so might have had IQs nearly as high as those of the White soldiers. Blacks in the military did indeed have higher IQs than did Blacks in the general population, but the same was true of White soldiers compared with the general White population. Flynn (1980) has argued that the evidence indicates that the gap in IQ between Black and White soldiers was the same as that in the U.S. population at large.”

Nisbett is correct here. Roughly 3% of the whites were excluded for having too low IQs, whereas 30% of the blacks were. So yes, “the same was true of White soldiers compared with the general White population.” We can only ponder as to why he didn’t say specifically what the exclusion rates were for each group, or how excluding the bottom 3% of the white population would only raise the average white soldier IQ about one point.

Rushton (2007)

In 2007 Philippe Rushton looked at South African University students. These were his results:

Group IQ Number
East Asians 116 23
Whites 113 398
South Asians (Indians / Pakistanis) 106 212
Coloreds 103 36
Blacks 98 887

For the blacks and mixed black-whites (coloreds) we would expect a compression effect, since you have to have a certain IQ to get into a university, and more blacks will not be smart enough to get in than coloreds. But even with this compression effect, we see coloreds intermediate between blacks and whites.

Udry (2003)

Richard Udry looked at the National Longitudinal Survey of Adolescent Health, and one of the things he did was look at the PVT and GPAs of different races and combinations. The whites, blacks, Asians, whites / Asians and mulattoes are included here:

Race % with “high GPA” % with “high PVT score” Number
White 32.27 26.98 46364
White / Asian 37.58 23.08 583
Asian 43.16 20.99 4133
Mulatto 24.19 18.2 416
Black 15.45 7.94 13530

The data here is not IQ data, though I could probably go find the raw scores and use this as more IQ data. The “high PVT score” of the Mulattoes compared to blacks is approximate confirmation of heredetarian views on all of this, but the real interesting thing here is with the White / Asian hybrids.

Because the hybrids are intermediate in BOTH GPA and PVT score – but whites score higher on PVT and lower on GPA than Asians. And the W/A hybrids were below the whites but above the Asians on PVT, and above the whites but below the Asians on GPA.

NAEP 2011

Using the NAEP explorer, the blogger from Unwelcome Discovery looked at the NAEP scores of Blacks, Whites and mixed Black-Whites in 2011.

Race Math Score Reading Score
White 293.6 274.6
Black-White Mixed 277.8 256.2
Black 263 249.2

I don’t know what the sample size for this was, but it’s the NAEP so it’s going to be huge.

In the future, if I have time, I would like to do this myself and get the sample size, and look at the Asian-White hybrids and see if they score intermediate on BOTH math and verbal even though Whites do better on verbal and Asians do better on math. That would be evidence that the composition of intelligence between whites and asians is down to genetics, not just the overall difference.

But in the mean time the NAEP is just one more log on the pile of the intermediate race = intermediate IQ general trend.


Most of the data on mixed-race people are of blacks and whites. In the future perhaps we’ll get more White-Asian hybrid data; and the silver lining of increased racemixing is that there will be more of them to test.

Of course you can always claim that mixed-race people have intermediate home environments, or face intermediate racism, but that complicates the environmental side of things. You’re now saying that mixed-race people face intermediate levels of hardship in such a way as to produce intermediate IQs.

The genetic side faces almost no complication. Sure, there are some examples when blacks score higher than whites, but we already knew that. And genes are a much simpler global explanation.

And with the PVT and GPA differences between whites and asians, the environmentalist now has to have a specific environmental explanation for that – because whites do better on the PVT, but have worse GPA, and mixed-race white-asian hybrids are intermediate on both. The genetic explanation is much simpler.

Facebook Comments
  • Mark Martinson

    Your point about Eyferth is excellent. It actually supports hereditarianism.

    • Mark Martinson

      I’m not sure why people keep making such a big deal about Eyferth. On the surface at least the Elsie Moore study is better.

  • Mark Martinson

    Am I the only one who has a hard time taking Nisbett seriously?



    The closest thing to direct evidence that the hereditarians have is a study from the 1970s showing that black children who had been adopted by white parents had lower I.Q.’s than those of mixed-race children adopted by white parents. But, as the researchers acknowledged, the study had many flaws; for instance, the black children had been adopted
    at a substantially later age than the mixed-race children, and later age at adoption is associated with lower I.Q.

    Granted no adoption study will be perfect for obvious reasons, but MTAS had a control group and follow up at 17.

  • Kris Polk

    To me, the funniest thing about the Eyferth study is that those who claim that the similar scores are a result of Germany’s less racist society must nevertheless still claim in a different context that German racism is to blame for the failure of Muslim immigrants to integrate.

    So Germany is more accepting of half-Black rape babies than German-born people of Turkish decent. Okay….

    Razor-sharp, pinpoint-accurate racism, which last time limited African-American opportunities while allowing Nigerian immigrants to circumvent discrimination because of their exotic accents and colorful attire, strikes again!

    • Mark Martinson

      Why doesn’t someone try to replicate the Eyferth study? It’s not as if US soldiers have stopped impregnating the natives.

      • Ryan Faulk

        What would they replicate? Eyferth vindicated heredetarianism.

        • Mark Martinson

          Well, try it again and see what the result is.

  • Emil Kirkegaard

    Just use simulated data to calculate the mean IQ of truncated normal distributions. R code:

    > tmp = rnorm(1e6, 85, 15)
    > mean(tmp)
    [1] 85
    > mean(tmp[tmp >= 77.14])
    [1] 92
    > tmp = rnorm(1e6, 100, 15)
    > mean(tmp[tmp >= 77.14])
    [1] 102

    So, about 92 for Blacks and 102 for Whites, using the same cutoff.

    There’s more problems. If the matings in Germany were consensual, we can be sure there was some selection for IQ due to assortative mating. The German women would have generally picked soldiers about equally smart to themselves. Since White soldiers were about the same level as the German women, this would have no effect on the mean IQ for them. However, it would have for the Blacks, by way of increasing the IQ of the selected soldiers towards the German mean. Since we don’t know the details, it’s hard to say how large the sorting was, but my meta-analysis of assortative mating for married couples found a mean r of .49. http://emilkirkegaard.dk/en/?p=4311 The effect of assortative mating is probably weaker here. I don’t know how to calculate the effect size, even if we know the degree of assortative mating.

    Funnily enough, a similar thing applies if the matings were rapes. Why? Because rapists tend to be less bright (say, mean IQ of 90 for Whites), and thus both the White and Black rapists were below average of their groups. Since the Black average was already lower, the effect is larger for them, and this means that the group difference between the White and Black rapists is smaller than that between the White and Black soldiers in general.