|AR Articles on Race and Intelligence|
|A King Among Men (Apr. 2003)|
|The Global Bell Curve (Dec. 2002)|
|The Definitive Word on Intelligence (Sep. 1998)|
|Race and Intelligence: The Evidence (Nov. 1992)|
|Research That Was to Prove Jensen Wrong Proves Him Right (Mar. 1994)|
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The naturalistic fallacy, identified by philosopher David Hume (1711–1776), occurs when reasoning jumps from statements about what is to prescription about what ought to be.
An example of the naturalistic fallacy: approving of all wars if scientific evidence showed warfare was part of human nature.
The converse of the naturalistic fallacy is the moralistic fallacy- jumping from prescriptions about what ought to be to statements about what is.
An example of the moralistic fallacy: claiming that, because warfare is wrong, it cannot be part of human nature.
The term moralistic fallacy was coined by Harvard University microbiologist Bernard Davis after calls for ethical guidelines to control the study what could allegedly become dangerous knowledge… such as the genetic basis of IQ.
For well over a generation, the study of the genetic and racial aspects of I.Q. has given rise to the best examples we have of the moralistic fallacy in action. Happily, under the sheer weight of evidence, there are now signs this anti-intellectual and unscientific prohibition is breaking down, at least in the academic world.
Despite repeated claims to the contrary, there has been no narrowing of the 15- to 18-point average IQ difference between Blacks and Whites (1.1 standard deviations). The differences are as large today as when first measured nearly 100 years ago. These differences, and the associated gaps in living standards, education levels etc., are rooted in factors that are largely heritable, not cultural. IQ differences are attributable more to differences in brain size than to racism, stereotype threat, item selection on tests, and all the other suggestions given by the commentators.
It is time to meet reality. It is time to stop committing the moralistic fallacy that good science must conform to approved outcomes.
In 1969, the Harvard Educational Review published a lengthy article by Berkeley educational psychologist Arthur Jensen How Much Can We Boost IQ and School Achievement? Jensen concluded:
- IQ tests measure socially relevant general ability;
- individual differences in IQ have a high heritability, at least for the White populations of the United States and Europe;
- compensatory educational programs have proved generally ineffective in raising the IQs or school achievement of individuals or groups;
- because social mobility is linked to ability, social-class differences in IQ probably have an appreciable genetic component; and tentatively, but most controversially,
- the mean Black-White group difference in IQ probably has some genetic component.
An enormous commotion ensued. Jensen’s conclusions, the theoretical issues they raised, and the public policy recommendations that many saw as stemming directly from them, were dubbed Jensenism, a term which entered the dictionary.
Since then, Jensen has quietly continued to publish. Steadily, his views have gained support amongst fellow social scientists.
In 1994, The Bell Curve by Richard Herrnstein and Charles Murray presented general readers an update of the evidence for the hereditarian position, along with several policy recommendations. They introduced to the general public the results of the 12-year National Longitudinal Survey of Youth. This had found that most 17-year-olds with high scores on the Armed Forces Qualification Test, regardless of ethnic background, went on to occupational success by their late 20s and early 30s. Those with low scores were more inclined to welfare dependency.
The study also found that the average IQ for African Americans was lower than those for Latino, White, East Asian, and Jewish Americans (85, 89, 103, 106, and 113, respectively).
Currently, the existence of the 15-to-18 point difference (1.1 standard deviations) between Blacks and Whites in the U.S. is not in itself a matter of empirical dispute. A meta-analytic review in Personnel Psychology in 2001 by Philip Roth and colleagues showed it also holds for college and university application tests, for tests for job applicants in corporate settings, and in the military.
Further, the Black-White IQ difference shows up before 3 years of age on most standardized test batteries, even after matching on maternal education and other variables. Therefore it is not due to poor education since this has not yet begun to exert an effect. (The East Asian IQ advantage appears by five years of age).
The question still remaining: is the cause of the group differences in average IQ purely social, economic, and cultural? Or are genetic factors also involved?
To attempt a definitive answer, I teamed up with Arthur Jensen and together we examined ten categories of scientific evidence from around the world published since Jensen’s path-breaking 1969 paper.
We concluded that the genetic component in Black-White differences is even higher than we had initially thought—likely 80%. This conforms to the default hypothesis laid out in Jensen’s 1998 book, The g Factor—that, by adulthood, genetic and cultural factors carry the exact same weight in causing the mean Black-White IQ difference as they do in causing differences between individuals in IQ—about 80% genetic/20% environmental.
For each set of data we contrasted a hereditarian model (50% genetic/50% cultural) and a culture-only model (0% genetic/100% cultural). Our 50/50 model did not exclude environmental factors, but it did require they be concretely demonstrable. Although the evidence we reviewed provided strong support for the genetic component of the model, we were unable to demonstrate any environmental element.
Our 60-page review, Thirty Years of Research on Race Differences in Cognitive Ability, was published as the lead article in the June 2005 issue of Psychology, Public Policy, and Law, a journal of the American Psychological Association, along with four responses—three critical—and our own reply (which lays out our refutations of our critics in some detail).
Here is some of the technical evidence we reviewed that led us to our conclusions:
1. The Worldwide Pattern of IQ Scores.
Around the world, the average IQ for East Asians centers around 106; for Whites, about 100; and for Blacks about 85 (in the United States) and only 70 in sub-Saharan Africa. The same rank-order of race differences is found for culture-fair tests and reaction time measures. (Reaction time tasks are so easy that all children can do them in less than one second. More intelligent children, measured by conventional IQ tests, perform faster on these tasks. East Asians average faster reaction times than Whites who have faster reaction times than Blacks.)
VDARE.com readers may recall I even traveled to South Africa to collect new IQ data to corroborate the remarkably low test scores reported for the general African population—mean IQ of 70. I tested IQ scores from highly-selected Black students at the prestigious University of the Witwatersrand in Johannesburg.
Seven studies conducted at universities in South Africa, including my own, yielded a median IQ of 84. Assuming that African university students are 1 standard deviation (15 IQ points) above the population mean, as university students typically are, the finding of a median IQ of 84 corroborates the general population mean of 70.
All over the world, mean IQs differ much less within major population groups than between them. Whites have IQs close to 100 whether they live in Europe, Canada, Australia, New Zealand, or South Africa, whereas Blacks in sub-Saharan Africa have IQs closer to 70 regardless of whether they live in East, West, Central, or Southern Africa—or whether the data were collected in the 1920s or the 2000s
This worldwide pattern contradicts the hypothesis that the low IQ of American Blacks is due to White racism. Many of the African countries showing a mean IQ = 70, such as Nigeria and Ghana, have been independent for half a century—and the Caribbean island of Haiti for two centuries. There has been no documented improvement in cultural achievement, or in IQ scores.
2. Race Differences are Most Pronounced on the More g-loaded components of tests.
Charles Spearman coined the term g for the general factor of mental ability (or general intelligence), which he postulated lay behind the observed ability of some children to do better than others in a wide range of seemingly unrelated tasks.
Some test items load more on the g factor than do other, more culturally malleable, items. A test’s g loading is the best predictor, not just of school grades and workplace performance, but also of all the other indicators and correlates of intelligence—including biological variables such as brain size, reaction times, and heritability estimates as calculated from twin studies.
Race differences are repeatedly found to be higher on more g-loaded tests. Because Black-White IQ differences are more pronounced on high g-loaded tests than on low g-loaded tests, the difference is unlikely to be the result of any idiosyncratic cultural peculiarities in this or that test. It is more likely to be due to heritage.
There is in fact no good evidence that g is affected by anything other than biology. That would require not just evidence that training produces higher scores, but also evidence of the broad transfer of training effects to other highly g-loaded tasks.
Test constructors could in principle reduce the Black–White difference to zero (or even reverse it) by including only non-g items (or those negatively loaded on g).
However, they would then be left with a test that had little or no predictive power.
3. Blacks and Whites Regress Toward Their Predicted (and Different) Means.
Basic genetic theory predicts that the IQ of offspring will regress towards the mean IQ of the population group from which the parents come. This has been amply documented for a number of physical traits in humans and in other species.
Regression to the mean is seen, typically, when individuals with high IQ scores mate. Their children tend to show lower scores than their parents. The converse happens for low IQ parents; they have children with somewhat higher IQs. This is because the parents pass on some, but not all, of their exceptional genes to their offspring. It is analogous to rolling a pair of dice and having them come up two 6’s or two 1’s. The odds are that on the next roll, you will get some value that is not quite as high (or as low).
Genetic theory predicts the precise magnitude of the regression effect. Culture-only theory makes no systematic or quantitative predictions. Black children with parents of IQ 115 regress to the Black IQ average of 85, while White children with parents of IQ 115 regress to the White IQ average of 100. Regression to a lower average IQ helps to explain the fact that Black children born to high IQ, wealthy, Black parents have test scores 2 to 4 points lower than do White children born to low IQ, poor White parents.
[VDARE.com note: This finding has important social and political implications. It means the strategy of buying off the black elite with affirmative action preferences cannot be a stable solution in the longer term, because the black elite’s children will not be able to take advantage of their parents’ success.]
4. The Gene-Environment Architecture of IQ is the Same in all Races.
Studies of Black, White, and East Asian twins show that the heritability of IQ is about the same in all races (50% or higher). There has been no indication of any special cultural influences—such as extreme deprivation, or being raised as a visible minority—being at work in one group and not in the others.
A strong genetic contribution is also indicated by Black-White differences being most pronounced on the more heritable components of tests.
One study even found that the degree of inbreeding depression (the tendency for inbred populations to suffer more intensely from various types of defects) found in various subtests conducted on the Japanese in Japan predicted the degree of Black-White differences found in the same subtests in the United States.
There is no known non-genetic explanation for inbreeding depression effects, or for why Japanese results can be used to predict Black-White differences on tests.
5. Brain Size Differences.
Larger brains are more intelligent because they contain more neurons and synapses and can process information more efficiently. Two dozen studies using magnetic resonance imaging (MRI) have shown that brain size is related to IQ differences within race with a correlation of about 0.40.
The different races also have different brain sizes. One study followed 50,000 children from birth to age 7. The East Asian American children in the sample averaged a larger head circumference at birth, 4 months, 1 year, and 7 years than did the White children, who in turn averaged a larger head circumference than did the Black children. By age 7, the East Asian American children had an average IQ of 110; Whites, 102; and Blacks 90.
The findings on race differences in brain size are highly reliable. They have been confirmed using four independent procedures—MRI, endocranial volume from empty skulls, wet brain weight at autopsy, and external head size measures.
How do our critics handle this evidence? Rather than refuting or challenging these facts, they completely ignore them.
6. Trans-Racial Adoption Studies.
Average race differences remain despite adoption of blacks by White middle-class parents. This has been demonstrated by a number of surveys, notably the Minnesota Transracial Adoption Study. The effects are especially noticeable after puberty.
7. Racial Admixture Studies.
Dozens of studies have found that lighter-skinned African Americans and the mixed-race Coloreds of South Africa (also lighter skinned) have average IQs between those of (for the most part) unmixed groups of Blacks and Whites. The mixed-race Colored population of South Africa has an average IQ of 85, intermediate to the respective African and White means of 70 and 100.
Research has shown that the finding is not due to lighter-skinned Blacks being treated better through expectancy effects or labeling theory. In the Minnesota Transracial Adoption Study, for example, some children were misclassified, with their adoptive parents wrongly believing that the mixed-race children had two Black biological parents. Yet these children had the same IQs as those of other mixed-race children correctly believed by their adoptive parents to have had one Black and one White biological parent.
The IQ of Blacks in the United States, around 85, is substantially higher than the IQs of Blacks in sub-Saharan Africa. There are two explanations for this. The first is that American Blacks have about 25% White ancestry. According to genetic theory this would raise their IQs above the level of Blacks in Africa. The second is that American Blacks enjoy much higher standards of living, nutrition, education, and health care than they have in societies run by Blacks.
Living in a White society has raised rather than lowered the IQs of American Blacks.
8. Race Differences are Seen Over a Wide Range of Issues.
East Asians and Blacks fall at the two ends of a continuum. Whites are in the middle. In addition to brain size and IQ, this shows up on a suite of 60 other life-history variables. These include speed of maturation and longevity, personality and temperament, family stability and crime, and sexual behavior and fertility.
One striking example: around the world the rate of dizygotic (i.e. two-egg) twinning is less than 4 per 1,000 births among East Asians, 8 among Whites, and 16 or greater among Blacks. The tendency to produce dizygotic twins is heritable and mediated by sex hormones.
Another example: Black babies sit, crawl, walk, and put on their clothes earlier than Whites or East Asians. For walking: East Asians, 13 months; Whites, 12 months; Blacks, 11 months.
Blacks also have an earlier age of sexual maturity than do Whites, who in turn have an earlier age than do East Asians, whether measured by age of first menstruation, first sexual experience, or first pregnancy.
9. Race Differences and Human Origins Research.
The fact that the three-way pattern in IQ, brain size, and other traits is not unique to the United States but occurs internationally is consistent with a single, genetic-evolutionary theory. The currently most commonly accepted view of human origins, the out-of-Africa theory, posits that Homo sapiens arose in Africa about 150,000 years ago and then expanded northward beyond Africa about 100,000 years ago, with a European-East Asian split about 41,000 years ago.
Evolutionary selection pressures were different in the hot savanna, where Africans lived, than in the cold northern regions Europeans experienced, or the even colder Arctic regions of East Asians.
Thus, the further north the ancestral human populations migrated out of Africa, about 100,000 years ago, the more they encountered the cognitively-demanding problems of gathering and storing food, gaining shelter, making clothes, and raising children successfully during prolonged winters.
As these populations evolved into present‑day East Asians and Europeans, the ecological pressures selected for larger brains, slower rates of maturation, and lower levels of sex hormone, and all the other life history characteristics.
10. Culture-Only Theory Hypotheses Fail to Account for the Race-IQ differences.
Culture-only theories do not explain the race differences in IQ. They have especially failed in explaining the East Asian data. The concept that Black-White IQ differences are due to differences in socio-economic status does not survive close examination . Adjusting for socioeconomic status only reduces the Black-White IQ difference by about one-third. Nor does the evidence support other culture-only hypotheses such as test bias, test anxiety, or the consequences of being a minority in a White society.
Massive society-wide interventions such as ending segregation, the subsequent nationwide program of school busing to achieve racial balance, and the Head Start programs have failed to reduce the differences. Head Start programs did produce modest gains in school retention and graduation rates among Whites—but not Blacks.
Large scale, often well-publicized, countywide amelioration projects (such as the $2 billion program in affluent Montgomery County, Maryland, as well as the Kansas City, Missouri, school district, under judicial supervision since 1985), have never yet made a replicable dent in the Black-White achievement gap (despite low student-teacher ratios and computers in every classroom).
The narrowing of the gap between Black-White social conditions has not led to any change in the magnitude of the Black-White IQ difference in over 100 years.
How do critics explain the fact that the Black-White difference is greater on backward than on forward digit span memory, or on the more complex rather than simple reaction time measures—exactly as predicted by Spearman’s (1927) hypothesis?
How do they explain the fact that Black students from families with incomes of $80,000 to $100,000 score considerably lower on the SAT than White students from families with $20,000 to $30,000 incomes?
How do they explain why social class factors, all taken together, only cut the Black-White achievement gap by a third?
Culture-only theory cannot predict these facts; often its predictions are opposite to the empirical results.
Discussing this evidence with those who, for whatever reason, refuse to consider the behavioral genetic or evolutionary aspect of race and intelligence is little more than arguing past one another.
But the harsh fact is that the more we remove environmental disadvantages, improving everybody’s intellectual performance, the greater will be the relative influence of genetic factors.
Equal opportunity will result in unequal outcomes—within families, between families, and between population groups.
Perhaps the fact that we have learned to live with the first, and to a lesser degree the second, offers some hope we can learn to do so for the third.
J. Philippe Rushton [email him] is a professor of psychology at the University of Western Ontario, the author of Race, Evolution, and Behavior: A Life History Perspective.
(Posted on December 8, 2005)