In 1944, the Swedish economist Gunnar Myrdal wrote a momentous book on race relations called An American Dilemma. In it, Myrdal blamed the underachievement of black people on prejudice and discrimination by white people. Political support for Myrdal’s analysis swept away hereditarian hypotheses and helped outlaw segregation in the 1954 Supreme Court Decision of Brown v Board of Education. Myrdal’s ideas also fueled the 1964 Civil Rights Act leading to school busing and affirmative action and to the War on Poverty, including Head Start programs. Whatever benefits may have resulted from this transformation of American society, blacks and whites were not equalized in IQ scores.

In this essay, I will show that equalizing environments cannot, in fact, remove black/white disparities in IQ because these are substantially genetic in origin. Indeed, my thesis is that racial differences go well beyond what is typically considered. First, the differences go beyond blacks and whites to define a three-way gradient from Orientals to whites to blacks. Second, the differences go beyond IQ scores to include brain size, reproductive physiology, personality and temperament, crime, speed of physical maturation, and longevity. Third, the differences go beyond the United States and are found internationally. Fourth, the differences go beyond environmental causation and are deeply rooted in gene-based evolutionary processes.

Although the historical record shows an African cultural disadvantage has existed, relative to Europeans and Asians, ever since Europeans first made contact over 2,000 years ago, it was possible to argue, until recently, that “reasonable doubt” existed about the genetic basis of black/white differences. Today, however, the evidence overwhelmingly favors the view that genes are required to explain the data. Surveys of experts in psychological testing and behavioral genetics show that most judge race differences in IQ to be genetic in origin.

The Bell Curve

If Myrdal’s 1944 book heralded an intellectual revolution, then Richard Herrnstein and Charles Murray’s The Bell Curve signaled the counter-revolution. This penetrating analysis of social mobility reported the results of a 12-year longitudinal study of 11,878 youths (3,022 of whom were African-American). Most 17-year-olds with high scores on the Armed Forces Qualification Test (black as well as white) went on to occupational success by their late 20s and early 30s whereas many of those with low scores went on to welfare dependency. The Bell Curve made it to the New York Times Bestsellers’ List of 14 weeks, selling over 400,000 copies and spawning several anthologies of commentary.

The predictive power of IQ scores had long been known by those familiar with the technical literature and interested in individual differences. But in the world of policy makers and pundits, The Bell Curve was a blockbuster, potentially altering the way they viewed the world, a fact not lost on its critics. The Bell Curve confirmed a genetic model of social stratification and, as such, improved on exclusively sociocultural and economic models. Blacks with IQs of 117, even those from disrupted ghetto families, were more likely to enter a profession than were whites with IQs of 100, even those from intact suburban families. Indeed, blacks with an IQ of 117 were twice as likely to enter a profession as were whites with an IQ of 117, presumably an effect of the affirmative action quota system.

Almost all commentators have accepted that the bell curve of IQ distribution for “African” Americans is offset lower than the ones for “Latino,” “white,” “Asian,” and “Jewish” Americans. (In The Bell Curve these IQ equivalents were 85, 89, 103, 106, and 115, respectively). The flashpoint of discussion, however, centered on whether the black/white difference is partly genetic. The Bell Curve presented a clear rendition of the usual syllogism, that (a) IQ test scores are heritable in both white and black populations, (b) white IQs are higher than black IQs, so (c) probabilistically, the white/black IQ difference is partly heritable.

The Bell Curve brought to attention Richard Lynn’s compilation of the international data on IQ showing that Orientals (people of Chinese, Japanese, and Korean descent) score higher on tests of mental ability than do whites, both within the U.S.A. and in Asia, whereas Africans and Caribbeans score lower. Lynn showed that Orientals in East Asia and North America typically have average IQs in the range of 101 to 111. Whites in Europe, South Africa, Australasia, and North America typically have average IQs of from 85 to 115 with an overall mean of 100. Blacks living south of the Sahara, in the Caribbean, in Britain, and in North America typically have IQs of from 70 to 90.

Especially noteworthy has been Lynn’s calculation of an IQ of only 70 for Africans south of the Sahara. Many reviewers expressed strong disbelief about such a low IQ, holding it impossible that, by European standards, 50 percent of black Africa is “mentally retarded.” But an African IQ of 70 has been confirmed in three studies since Lynn’s 1991 review, each of which used Raven’s Progressive Matrices, a test usually regarded as an excellent measure of the non-verbal component of general intelligence and one not bound by culturally specific information. First, Kenneth Owen found a black African IQ of 70 in a sample of over 1,000 South African 13-year-olds. Second, Fred Zindi, a black Zimbabwean, found an African IQ of 70 in a study that matched 204 12- to 14-year-old Zimbabwean students and 202 English students for sex, educational level, and “working class” background. Third, Richard Lynn found an African IQ of 70 in a study of Ethiopian immigrants to Israel.

Of course, questions can be raised about the validity of using tests for racial comparisons. However, because the tests show similar patterns of internal item consistency and predictive validity for all groups and because the same differences are found on relatively culture-free tests, most psychometricians think that the tests are valid measures of racial differences. This was also the judgement of a recent Task Force Report from the American Psychological Association.

Speed of decision making (reaction time) in 9- to 12-year-olds shows the same three-way racial pattern as do test scores. Children were asked to decide which of several lights was on or stood out from others and move a hand to press a button. All the children could perform the task in less than one second, but children with higher IQs performed it faster than those with lower scores. Richard Lynn found that Oriental children from Hong Kong and Japan were faster in reaction time (controlling for movement time) than were white children from Britain and Ireland, who in turn were faster than black children from South Africa. Arthur Jensen found this same pattern of racial differences in California.

Racial Differences in Brain Size

A small but robust relation has been firmly established between IQ scores and brain size. This relationship has been most clearly shown using Magnetic Resonance Imaging (MRI) which creates, in vino, a three dimensional image of the brain. The strength of the relationship between brain size and IQ (r = 0.40) is roughly equivalent to the strength of the relationship between social class and IQ. Lower correlations can be found between head circumference measures and IQ. The correlation here is about 0.20 but the relationship is robust, having been found for many different ages and in many different populations.

The results from numerous modern studies converge on the conclusion that the brains of Orientals and their descendants average about 17 cubic centimeters (one cubic inch) larger than those of Europeans and their descendants, whose brains average about cubic 80 centimeters (five cubic inches ) larger than those of Africans and their descendants. This racial gradient has been independently established using three procedures: (a) wet brain weight at autopsy, (b) volume of empty skulls using filler, and (c) volume estimated from external head sixes. Recently, (d) a MRI study has confirmed the white/black difference.

Consider just a few of the recently conducted studies, some from the U.S. and others from around the world, showing again the universality of the racial pattern. Dr. Khang-Cheng Ho and his associates at the Medical College of Wisconsin reported autopsy brain weights on 1,261 individuals. Holding constant age, sex, and body size, they found that white Americans averaged a brain weight of 1,323 grams whereas black Americans averaged 1,223 grams. Kenneth Beals and his colleagues in anthropology examined endocranial volume in up to 20,000 skulls from around the world and found that East Asians, Europeans, and Africans averaged cranial volumes of 1,415, 1,362, and 1,268 cubic centimeters, respectively. A study by me using head measurements, from a stratified random sample of 6,325 U.S. Army personnel, found that Orientals, whites, and blacks in the U.S. Army averaged 1,416, 1,380, and 1,359 cubic centimeters, respectively. Another study by me using head sizes, this time from tens of thousands of men and women collated by the International Labour Office from around the world, found that Asians, Europeans, and Africans averaged 1,308, 1,297, and 1,241 cubic centimeters, respectively. Finally, a study in Britain used MRI and found Africans and Caribbeans averaged a smaller brain volume than did British whites.

Racial differences in brain size show up early in life. Data from the National Collaborative Perinatal Project on 19,000 black children and 17,000 white children show that black children have a smaller head circumference at birth and, although black children are born shorter in stature and lighter in weight than white children, by age seven “catch-up growth” leads black children to be larger in body size than white children but still smaller in head circumference. In this study, head circumference at birth was found to correlate with IQ at age seven in both black and white children.

Family Structure, Testosterone, and Personality

Learning to follow rules is traditionally thought to depend on family socialization. Since the 1965 Moynihan Report documented the high rates of marital dissolution, frequent heading of families by women, and numerous illegitimate births, the figures cited as evidence for the instability of the black family in America have tripled. A similarly constituted matrifocal black family in is found in the Caribbean, with father-absent households and a lack of paternal certainty. Moreover, there is separate bookkeeping by co-habitants; even when blacks are married, the tendency is not to pool resources, implying a readiness to part company. The Caribbean pattern, like the American one, is typically attributed to the long legacy of slavery. The slavery hypothesis, however, does not fit data from sub-Saharan Africa. Reviewing long-standing African marriage systems in the 1989 issue Ethology and Sociobiology. Patricia Draper of Pennsylvania State University summarized:

coupled with low investment parenting is a mating pattern that permits early sexual activity, loose economic and emotional ties between spouses . . . and in many cases the expectation on the part of both spouses that the marriage will end in divorce or separation, followed by the formation of another union.

The African marriage system may depend partly on hormonally based traits of personality. Biological variables such as the sex hormone testosterone are implicated in the tendency toward multiple relationships as well as to commit crime. One study, published in the 1993 issue of Criminology, showed clear evidence of a testosterone-crime link based on an analysis of 4,462 U.S. military personnel. Other studies have linked testosterone to an aggressive and impulsive temperament and also to sexual behavior. Testosterone levels help to explain why young men are disproportionately represented in crime statistics relative in young women, and why younger people are more trouble-prone than older people. Testosterone reliably differentiates the sexes and is known to decline with age.

Race differences exist in average testosterone levels. Studies show three to 19 percent more testosterone in black college students and military veterans than in their white counterparts. Studies among the Japanese show a correspondingly lower amount of testosterone than among white Americans. Some investigations were carried out by medical researchers interested in cancer of the prostate, one determinant of which is testosterone. Black men have higher rates of prostate cancer than white men, who in turn have higher rates than Oriental men.

Hormones may also influence personality and temperament. International data show that blacks are more talkative, less restrained and more excitable than whites. Whites in turn are more talkative, less restrained and more excitable than Orientals. With infants and young children, observer ratings are the main method employed whereas with adults the use of standardized tests are more frequent. One study in French-speaking Quebec examined 825 4- to 6-year-olds from 66 countries rated by 50 teachers. All the children were in preschool French-language immersion classes for immigrant children. Teachers consistently reported better social adjustment and less hostility-aggression form East Asian than from white than from. African-Caribbean children. Another study based on 25 countries from around the world showed that East Asians were less extroverted and more anxiety-prone than Europeans, who in turn were less outgoing and more restrained than Africans.

Speed of Maturation

In the United States, black mothers have long been known to have a shorter gestation period than white mothers. By week 39, 51 percent of black children have been born, whereas the figure for white children is 33 percent. Similar results have been observed in Europe, where women of European ancestry have been compared with women of African ancestry. Other observations reveal that, although black babies are born earlier, they are physiologically more mature than white babies, as measured by pulmonary function and amniotic fluid.

Black precocity in physical maturation continues through life. On well-standardized tests, scores indicate that black babies from Africa, the Caribbean, and the United States mature faster than white babies on measures taken from birth to 12 months in coordination and head lifting, in muscular strength and turning over, and in locomotion; at 15 to 20 months, black babies are more advanced in the ability to put on clothing. In contrast, on well-standardized measures, Asian children are more delayed than white children. Asian children typically do not walk until 13 months, compared with 12 months for white children and 11 months for black children. Regarding dental development, African samples begin the first phase of permanent tooth eruption at age 5.8 years and finish at 7.6 years; Caucasoids begin at 6.1 years and finish at 7.7 years; and Mongoloids begin at 6.1 years and finish at 7.8 years.

Behavioral life-cycle traits show a similar set of differences among the three populations. These include age at first intercourse and age at first pregnancy, as well as longevity. For example, at all ages, blacks have higher mortality rates from numerous causes than whites in the United States, and the gap has widened over the last 30 years. Asians have lower mortality rates than whites.

Rate of Ovulation, Sexuality, and AIDS

Sex hormones also influence reproductive physiology. Whereas the average woman produces one egg every 28 days in the middle of the menstrual cycle, some women have shorter cycles and others produce more than one egg, both events that translate into greater fecundity including the birth of dizygotic twins. The rate per 1,000 births is fewer than four among East Asians, eight among whites, and 16 or more among Africans and African-Americans.

Racial differences exist in sexual behavior, as documented by numerous surveys including some carried out by the World Health Organization. Africans, African-Americans, and blacks living in Britain are more sexually active, at an earlier age, and with more sexual partners than are Europeans and white Americans, who in turn are more sexually active, at an earlier age, and with more sexual partners than are Asians, Asian-Americans, and Asians living in Britain. Sexual behavior translates into consequences, including pregnancies and sexually-transmitted diseases such as AIDS.

The rapid worldwide rate of increase in AIDS continues (currently 26 percent a year) and, in its latest report, the World Health Organization showed that over one and a quarter million adult cases had been reported from 193 countries as a result of the pandemic. Allowing for under-diagnosis, incomplete reporting, and reporting delay, the true figure is estimated to be about six million, and approximately 17 million people are estimated to have the human immunodeficiency virus (HIV) which causes the disease.

The World Health Organization extrapolates for each country the per capita prevalence of HIV. The results for 1996 are truly stunning. Forty-seven countries are currently estimated to have one percent or more of their sexually active population living with HIV. Thirty-seven of these countries are in sub-Saharan Africa and seven are in the Caribbean. A sampling: Botswana, Zimbabwe, Zambia, and Uganda have upwards of 20 percent or more of their sexually active population living with HIV; South Africa, Kenya, Mozambique, and Zaire have from three to ten percent living with HIV; in the Caribbean, Haiti, Bahamas, Barbados, and Belize have two percent or more of their population infected; and Jamaica, Bermuda, and the Dominican Republic have more than one percent.

U.S. data show that African-Americans have rates similar to their counterparts in black Africa and the black Caribbean, with three percent of black men and one percent of black women living with HIV. This survey, appearing in Science, drew correspondence to the effect that “race” was not causal to the incidence rates but was merely a marker for social factors such as poverty, which were the real causes. The author of the report replied, however, noting that (1) even with socioeconomic indicators controlled, sexually transmitted infections remained higher among African-Americans than among other groups and (2) “cultural variations in behavior,” distinct from socioeconomic status, were part of the complex web of causation. Noe of the correspondents pointed to the racial distribution elsewhere in the world nor to the fact that in Africa, it is high socioeconomic status that puts people at risk, mainly by increasing their access to sexual partners. Throughout the world, the virus must be considered endemic to black populations.

Heritability of Racial Differences

The worldwide consistency of the Oriental-white-black gradient on so many variables makes it very likely that some of the differences are genetic. Of course, environmental factors such as poor nutrition, and the presence of parasites like tapeworms do have effects on brain size and behavior. No one is arguing that the racial differences are 100 percent genetic. Instead, the argument is between “hereditarians” like Arthur Jensen, Michael Levin, Richard Lynn, and me who hold to a mixed genetic-environmental model, say about 50 percent genetic and 50 percent environmental, and the “egalitarians” who hold, in effect, that racial differences are 100 percent environmental.

Theories of racial differences based on 100 percent cultural transmission have formidable problems accounting for the physiological traits such as speed of dental and physical maturation, brain size, gamete production, and testosterone production as well as the consistency of the racial rankings across time and culture. Direct evidence for between-group heritabilities also exists. For example, the racial differences in multiple birthing are independently heritable through the race of the mother and not through the race of the father, as found in Oriental/white crosses in Hawaii and white/black crosses in Brazil.

Estimates of the heritability of IQ among whites routinely range from 40 percent to 80 percent. Similar heritabilities are also found among black Americans, Oriental Americans, Koreans, and the Japanese in Japan. In a study of the heritability of cranial size among 236 pairs of adolescent twins, both blacks and whites, Travis Osborne and I found the genetic contribution ranged from 38 percent to 51 percent depending on particular adjustments for body size. It seems reasonable to generalize these high within-group heritabilities to the between-group differences.

More direct evidence for the heritability of racial differences comes from adoption studies. Korean and Vietnamese children adopted into white American and white Belgian homes grow to have IQs ten or more points higher than their adoptive national norms. As babies, many of these children had been hospitalized for malnutrition. By contrast, black and mixed-race (black/white) children adopted into white middle-class families typically perform at a lower level than white siblings with whom they have been raised. One well-known study is the Minnesota Transracial Adoption Study. By age 17, adopted white children had an average IQ of 106, an aptitude based on national norms at the 59th percentile, and a class rank at the 54th percentile; adopted mixed-race children had an average IQ of 99, an aptitude at the 53rd percentile, and a class rank at the 40th percentile; and adopted black children had an average IQ of 89, an aptitude at the 42nd percentile, and a class rank at the 36th percentile.

As shown in the above table, the mixed-race children had scores intermediate to the “all-white” and “all-black” children. Numerous studies have shown similar results with lighter skin typically correlating with higher IQ. William Shockley estimated that for low-IQ black populations, there is a one-point increase in average “genetic” IQ for each one percent of Caucasian ancestry, with diminishing returns as an of IQ of 100 is reached. Overall, using blood tests and DNA markers, studies show that African-Americans have about 25 percent European genes. It is interesting to note in this regard that Cape Coloreds, a mixed-race population in South Africa, average an IQ of 85, mid-way between non-mixed black South Africans with an IQ of 70 and white South Africans with an IQ of 100.

More technical evidence for the genetic basis of the racial differences in IQ comes from studies using differential heritabilities. Some items and subtests are more genetically influenced than are others. The more genetically influenced the subtests, the more it differentiates between blacks and whites. A very similar relation is found with the general factor of intelligence (known as g) showing that different IQ tests tend to be related. More g-loaded tests also tend to be more heritable. Although heritability and g-loaded tests also tend to be more heritable. Although heritability and g-loadedness are conceptually distinct, both differentiate blacks from whites. Thus, while the white/black IQ gap averages 15 points, the difference is substantially more pronounced on tests of high heritability and high g than it is on tests of low heritability and low g. Here is a situation in which environmental and genetic hypotheses predict opposite outcomes. Environmental theory predicts racial differences will be greater on more culturally influenced tests whereas genetic theory predicts racial differences will be greater on more heritable and g-loaded tests.

Evolutionary Origins of Race Differences

Evolutionary selection pressures are different in the hot African savanna where Negroids evolved than they are in the cold Arctic, where Mongoloids evolved. The modern “African Even” theory of human origins posits a beginning in Africa some 200,000 years ago, an exodus through the Middle East with an African/non-African split about 110,000 years ago, and a Caucasoid/Mongoloid split about 41,000 years ago. This evolutionary sequence fits with and helps to explain how and why the variables cluster. The further north the populations migrated out of Africa, the more they encountered the cognitively demanding problems of gathering and storing food, acquiring shelter, making clothes, and raising children successfully during the prolonged winters. As the original African populations evolved into present-day Caucasoids and Mongoloids, they did so in the direction of larger brains, slower rates of maturation, and lower levels of sex hormone with concomitant reductions in sexual potency, aggressiveness and impulsiveness, and increases in family stability, advance planning, self-control, rule following, and longevity.

To my mind, little or no reasonable doubt remains about the genetic basis for at least some of the racial differences. I am aware of no environmental factor able to explain either the consistency of the international racial pattern across so many diverse variables or the tradeoff between brain size and gamete production in which people of East Asian ancestry average the largest brains and the lowest twinning rate, people of African ancestry average the smallest brains and the highest twinning rate, and people of European ancestry average intermediately in both. Only gene-based life-history theories predicting tradeoffs between parental care and reproductive effort fit all the data.

Conclusion

Recognizing that the pattern in achievement, crime, and family organization is not unique to the United States but occurs internationally shows the need for a more general (genetic-evolutionary) theory than the particularized explanations typically provided. The behavioral profile of blacks in America is like those for blacks in Africa and the Caribbean and so cannot be due to “white racism” or other cultural features unique to the U.S. Similarly, whites and Asians in America behave like their counterparts elsewhere in the world. Traditional environmental explanations based on Asian family strength and African poverty are themselves explained by an evolutionary perspective.

Policy analysts need to rethink attitudes about race differences and acknowledge their international distribution and genetic basis. Based on the evidence, two important predictions can be made about the future course of world history. First, with respect to economic and scientific achievements, the Oriental populations of the Pacific Rim must be expected to continue to grow in accomplishments until they eventually equal or outdistance the predominantly Caucasian populations of North America and Western Europe. Second, with respect to the HIV and AIDS pandemic, mortality among black Americans must soon be expected in large proportions. Given the costs involved in providing custodial care, it may be the AIDS catastrophe that finally breaks down the taboo on discussing the genetic basis of race.

Editor’s Note: This essay is included in the book, The Real American Dilemma: Race, Immigration, and the Future of America, available at the American Renaissance store.