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Race and intelligence is a controversial area of intelligence research studying the nature, origins, and practical consequences of racial and ethnic group differences in intelligence test scores and other measures of cognitive ability. This research is grounded in several controversial assumptions:

• the social categories of race and ethnicity are concordant with genetic categories, such as biogeographic ancestry.
• intelligence is measurable (see psychometrics) and is dominated by a unitary general cognitive ability.

Much of the evidence currently cited is based on IQ testing in the United States. While the distributions of IQ scores among different racial-ethnic groups overlap considerably, groups differ in where their members cluster along the IQ scale. Similar clustering occurs with related variables, such as school achievement, reaction time, and brain size, and the gap shows up before age 3 on most standardized tests after matching for variables such as maternal education. Most variation in IQ in the U.S. occurs within individual families, not between races. However, even small differences in average IQ at the group level might theoretically have large effects on social outcomes. For example, a randomly selected group of Americans with an average IQ of 103 had a poverty rate 25% lower than a group with an average IQ of 100. Similar substantial correlations in high school drop-out rates, crime rates, and other outcomes have been measured.

Many hypotheses have been proposed to explain racial-ethnic group differences in IQ. Certain environmental factors, such as nutrition, are thought to modulate IQ in children, and other influences have been hypothesized, including education level, richness of the early home environment, and other social, cultural, or economic factors. The primary focus of the scientific debate is whether group IQ differences also reflect a genetic component. Hereditarianism hypothesizes that a genetic contribution to intelligence could include genes linked to neuron structure or function, brain size or metabolism, or other physiological differences which could vary with biogeographic ancestry.

The findings of this field are often thought to conflict with fundamental social philosophies, and have thus engendered a large controversy. Some of the researchers who publically argue for the partly genetic hypothesis have received grants from the Pioneer Fund, which has been accused of racism by some scientists and the SPLC. Other scientists, such as Steven Pinker, argue unnecessary fear of the implications of the science of human nature has led to large swaths of the intellectual landscape being reengineered to deny fundamental aspects of human nature. Media portrayal of the role of genetic and environmental factors in explaining individual and group differences in IQ was shown in a 1988 study to be misleading regarding mainstream expert opinion. Some critics examine the fairness and validity of cognitive testing and racial categorization, as well as the reliability of the studies and the motives of the authors, on both sides. Some critics fear the misuse of the research, question its utility, and feel that comparing the intelligence of racial groups is itself unethical. For instance, the disparity in average IQ among racial groups is sometimes mistaken for the idea that all members of one race are more intelligent than all members of another, or that ranking group IQ averages from "high" to "low" implies a moral ranking of races from "good" to "bad" or an overall ranking of "superior" to "inferior". The conclusion that some racial groups have lower average IQ scores, and the hypothesis that a genetic component may be involved, have led to heated academic debates that have spilled over into the public sphere.

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Background information

Race

| See also: Race and multilocus allele clusters

Racial distinctions are generally made on the basis of skin color, facial features, inferred ancestry, national origin and self-identification. In an ongoing debate, some geneticists argue race is neither a meaningful concept nor a useful heuristic device, and even that genetic differences between groups are biologically meaningless, on the basis of that more genetic variation exists within such races than between them, and that racial traits overlap without discrete boundaries. Other geneticists, in contrast, argue that categories of self-identified race/ethnicity or biogeographic ancestry are both valid and useful , that these categories correspond with clusters inferred from multilocus genetic data, and that this correspondence implies that genetic factors might contribute to unexplained phenotypic variation between groups.

It is well known that many alleles vary in frequency across human populations. While most of this variation is selectively neutral and has no obvious phenotypic effect, a significant portion of human genes do show evidence of recent natural selection, leading to functional differences between populations. Recent studies have shown that some genes involved in brain development and other neuronal functions have variants that have spread to high frequencies under selective pressure and now occur in substantially different frequencies in different global populations. However, their effect, if any, on IQ is unknown. (Discussed below.)

Worldwide, human populations are geographically bounded into five less than perfectly distinct continental areas: the Americas, Eurasia (including Europe, North Africa and West Asia), East Asia, Sub-Saharan Africa, and the Pacific Islands (including Australia). At least for subjects of biomedical research in the United States, self-identified racials labels correspond to geographic regions of genetic ancestry, with only a small number of individuals showing genetic cluster membership different from their self-identified race/ethnicity. People labeled Blacks have most of their ancestors from sub-Saharan Africa, Whites from Europe (and sometimes the Middle East and North Africa), and East Asians from the north-western Pacific Rim. Hispanics form a genetically diverse group that includes many recent U.S. immigrants of mixed ancestry, and are more often called an ethnic group.

The political, social and cultural structure of the United States is still weighted by race. It was only in the 1960s that racial discrimination became illegal in many areas of public and private life, including employment and housing, and some consider discrimination to remain prevalent. The national and state governments of the United States employ racial categorization in the census, law enforcement, and innumerable other ways. Many political organizations intend to represent the interests of specific racial groups. See the articles Race and Race (U.S. Census) for further discussion.

Intelligence testing

Intelligence is most commonly measured using IQ tests. These tests are often geared to be good measures of the psychometric variable g, and other tests that measure g (for example, the Armed Forces Qualifying Test and the SAT) also serve as measures of cognitive ability.

All such tests are often called "intelligence tests," though the use of the term "intelligence" is itself controversial. It is clear, however, that performance in these tests accurately predicts performance in similar life tasks (typical college courses, for example). The correlation with many real-world results is lower. For example, while the correlation of IQ with job performance is strong, income is modestly correlated and accumulated wealth is only weakly correlated. The genetic transmission of wealth via IQ is near zero. As commonly used, "IQ test" denotes any test of cognitive ability, and "IQ" is used as shorthand for scores on tests of cognitive ability. Some critics question the validity of all IQ testing or claim that there are aspects of "intelligence" not reflected in IQ tests. Historically, criticisms of the validity of IQ testing focused primarily on questions of "test bias", which has many related meanings. Several conclusions about tests of cognitive ability are now largely accepted:

• IQ scores measure many, but not all of the qualities that people mean by intelligent or smart (for example, IQ does not measure creativity, wisdom, or personality)
• IQ scores are fairly stable over much of a person's life
• IQ tests are predictive of school and job performance, to a degree that does not significantly vary by socio-economic or racial-ethnic background
• For people living in the prevailing conditions of the developed world, cognitive ability is substantially heritable, and while the impact of family environment on the IQ of children is substantial, after adolescence this effect becomes difficult to detect.

See the articles Intelligence, IQ, and general intelligence factor for further discussion of the validity of these tests.

The contemporary debate: results and interpretations

The contemporary scholarly debate about race and intelligence involves both the relatively uncontroversial experimental results that indicate that average IQ test scores vary among racial groups, and the relatively more controversial interpretations of these IQ differences. In general, contemporary interpretations of the "IQ gap" can be divided into three broad categories:

1. "culture-only" or "environment-only" interpretations that posit overwhelmingly non-genetic causes (for example, socioeconomic inequality or minority group membership) that differentially affect racial groups; and
2. "partly genetic" interpretations that posit an IQ gap between racial groups caused by approximately the same matrix of genetic and environmental forces that cause IQ differences among individuals of the same race.
3. "insufficient data": no meaningful interpretation can be made based on available evidence.

History

1850s to World War II

The scientific debate on the contribution of nature versus nurture to individual and group differences in intelligence can be traced to at least the mid-19th century. Charles Darwin wrote in his Descent of Man (VII, On the races of Man): "he various races, when carefully compared and measured, differ much from each other—as in the texture of hair, the relative proportions of all parts of the body, the capacity of the lungs, the form and capacity of the skull, and even the convolutions of the brain. But it would be an endless task to specify the numerous points of difference. The races differ also in constitution, in acclimatization and in liability to certain diseases. Their mental characteristics are likewise very distinct; chiefly as it would appear in their emotional, but partly in their intellectual faculties."

The writings of Sir Francis Galton, elaborating on the work of his cousin Darwin, spurred interest in the study of mental abilities, particularly as they relate to heredity and eugenics.

The fact that there are differences in the brain sizes and brain structures of different racial and ethnic groups was well known and widely studied during the 19th century and early 20th century. Average ethnic and racial group differences in IQ were first found due to the widespread use of standardized mental tests during World War I.

Beginning in the 1930s, hereditarianism — the belief that genetics contribute to differences in intelligence among humans — began to fall out of favor, in part due to the advocacy of Franz Boas, who in his 1938 edition of The Mind of Primitive Man wrote, "there is nothing at all that could be interpreted as suggesting any material difference in the mental capacity of the bulk of the Negro population as compared with the bulk of the White population." The hereditarian position was greatly weakened by Boas' finding that cranial vault size had increased significantly in the U.S. from one generation to the next, because racial differences in such characteristics had been among the strongest arguments for a genetic role. Inspired by the American eugenics movement, Nazi Germany implemented the T-4 Euthanasia Program in which roughly 200,000 mentally and physically disabled Germans were killed, and about 400,000 sterilized.

Post WWII and modern times

Due in part to the association of hereditarianism with Nazi Germany, after the conclusion of World War II until the 1994 publication of The Bell Curve, it became largely taboo to suggest that there were racial or ethnic differences in measures of intellectual or academic ability and even more taboo to suggest that they might involve a genetic component.

In 1961, the psychologist Henry Garrett coined the term equalitarian dogma to describe the then politically fashionable view that there were no race differences in intelligence, or if there were, they were purely the result of environmental factors. Those who questioned these views often put their careers at risk.

The contemporary scholarly debate on race and intelligence may be traced to Arthur Jensen's 1969 publication in the Harvard Educational Review of "How Much Can We Boost IQ and School Achievement?" In this paper, he wrote on some of the major issues that characterize the partly genetic hypothesis of racial IQ differences, and on compensatory educational programs. Reports on Jensen's article appeared in Time, Newsweek, Life, U.S. News & World Report, and The New York Times Magazine.

Press attention returned to the issue of race and intelligence in 1994 with the publication of The Bell Curve, which included two chapters on the subject of racial difference in intelligence and related life outcomes. In response to The Bell Curve, Stephen Jay Gould updated The Mismeasure of Man in 1996. Among other things, he criticized the IQ test as a measure of intelligence, citing what he perceived as inherent racial and social biases as well as systematic flaws in the testing process.

The introduction of biomedicine tailored to the genetics and disease patterns of specific racial groups is currently one of the factors adding to the complexity and controversy of debates on race and science. In 2006, the scholarly debate continues on the question of "whether the cause of group differences in average IQ is purely social, economic, and cultural or whether genetic factors are also involved".

Public controversy

Media portrayal

Media portrayal of intelligence-related topics, including race and intelligence research, was found in a 1987 study to be misrepresentative of opinion among scholars in relevant fields, including subfields of psychology, sociology, cognitive science, education, and genetics. Among these scholars, 53% thought that the Black-White gap was partially genetic and 17% thought it was entirely environmental, but media reports were found to misrepresent the majority view and portray scholars in the minority as representative of mainstream opinion in their fields.(See below: Expert opinion.)

A 2004 study found widespread and systematic research misinterpretation regarding one of the more popular explanations for the IQ gap. Introducing stereotype threat to a test-taking environment has been shown to increase the existing gap between Blacks or Whites in relation to Whites or Asians respectively, and has thus been offered as a potential contributor to the gap. However, 88% of accounts in the popular media, 91% in scientific journals, and 67% in psychology textbooks misinterpreted the findings as that eliminating the introduced stereotype threat eliminated the Black-White gap, when in fact the students had already been matched according to prior scores. The authors suggest the appeal of the misinterpreted findings may have been a factor, and that such research results in general may in this way be systemically more readily accepted.

Utility of research and racism

One criticism of race and intelligence research, regardless of whether racial differences are genetic or not, questions its utility. It's been argued that society might actually be better off "with an untruth: that there is no good reason for this inequality, and therefore society is at fault and we must try harder."

The Southern Poverty Law Center has stated: "Race science has potentially frightening consequences, as is evident not only from the horrors of Nazi Germany, but also from the troubled racial history of the United States. If white supremacist groups had their way, the United States would return to its dark days. In publication after publication, hate groups are using this "science" to legitimize racial hatred."

Some scientists, including W. D. Hamilton, considered one of the greatest evolutionary theorists of the 20th century, argue that suppressing race and intelligence research is actually more harmful than dealing with it honestly. Linda Gottfredson argues:

Lying about race differences in achievement is harmful because it foments mutual recrimination. Because the untruth insists that differences cannot be natural, they must be artificial, manmade, manufactured. Someone must be at fault. Someone must be refusing to do the right thing. It therefore sustains unwarranted, divisive, and ever-escalating mutual accusations of moral culpability, such as Whites are racist and Blacks are lazy.

Steven Pinker argues that opposition to racism is based on moral, not scientific assumptions, and is not vulnerable to being disproved by bioscientific advances. "The case against bigotry is not a factual claim that humans are biologically indistinguishable. It is a moral stance that condemns judging an individual according to the average traits of certain groups...". Pinker suggests that intellectual life may not at present be prepared to deal with this area of inquiry.

Coming advances in genetics and genomics are expected to soon provide the ability to test hypotheses about group differences rigorously, whether between races, sexes, or other groups, in cognitive traits or temperament, musical or athletic talent, or in responses to biomedical treatments. Some scientists predict this will be the source of one of the biggest social and intellectual issues of the coming decades.

Accusations of bias

The largest source of funding for proponents of the partly genetic interpretation, the Pioneer Fund, has been criticized by some critics as having a eugenic and racist political agenda, and has been characterized by the controversial Southern Poverty Law Center as a "hate group," using the definition "attack or malign an entire class of people, typically for their immutable characteristics". Other critics regard the fund as having had an ultimately positive effect. Some critics have found it significant that some of the prominent researchers advancing genetic explanations have also opposed affirmative action and school integration.

Steven Pinker argues a fear of the implications of the science of human nature ("mind, brain, genes, and evolution") has led to the perception that these are dangerous ideas. Pinker argues this has resulted in a denial of human nature in which "large swaths of the intellectual landscape have been reengineered to try to rule hypotheses out a priori (race does not exist, intelligence does not exist, the mind is a blank slate inscribed by parents)." Scientists working in these areas have in the past been targets of censorship, violence, and comparisons to Nazis.

Average test score gaps among races

The modern controversy surrounding intelligence and race focuses on the results of IQ studies conducted during the second half of the 20th century, mainly in the United States and some other industrialized nations. In almost every testing situation where tests were administered and evaluated correctly, a difference of approximately one standard deviation was observed in the US between the mean IQ score of blacks and whites. Most attempted compilations of average IQ by race place Ashkenazi Jews at the top, followed by East Asians, whites, Hispanics and Native Americans, African Americans, Sub-Saharan Africans, and Indigenous Australians.

Some other psychological traits, such as behavioral inhibition, have also been found to vary significantly in distribution among ethnicities, but group differences in tests of cognitive ability have been the subject of more attention, as they are seen by some as one of society's most pressing problems.

World-wide scores

See also: Race Differences in Intelligence

The largest review of the global cognitive ability data is Richard Lynn's 2006 Race Differences in Intelligence, which organizes the data by the nine global genetic clusters identified in previous genetic cluster analysis. In general, Lynn lists East Asians and Europeans as demonstrating the highest average scores, indigenous Americans and other Eurasians with intermediate average IQ, and Africans and Australian Aborigines with the lowest average IQ. Lynn's 2006 survey totals 620 published IQ studies from around the world, surveying a total of 813,778 tested individuals, and is an expansion by four times of the data collected in his 2002 IQ and the Wealth of Nations with Tatu Vanhanen. IQatWoN received strong criticism for both error and alleged bias, but has also been used as a source of IQ data and hypotheses used in several peer-reviewed studies.

IQ scores vary greatly among different nations for related groups. Black Africans score much lower than blacks in the US, although Black Americans average about 7-20% European admixture. Some reports indicate that the black–white gap is smaller in the UK than in the U.S. but UK admixtures are not well-studied. Many studies also show differences in IQ between different groups of whites. In Israel, large gaps in test scores and achievement separate Ashkenazi Jews from other groups such as the Sephardi.

Brain size, employment tests, and school achievement

IQ has a low to moderate correlation with various measures of brain size and performance on elementary tests of response time. For example, a 2005 meta-analysis found that brain size correlates with IQ by a factor of approximately .40 among adults. Reaction times correlate with IQ by about .30 to .50. Studies have shown racial differences in both brain size and tests of response time. Cranial vault size and shape have changed greatly during the last 150 years in the US. These changes must occur by early childhood because of the early development of the vault. The explanation for these changes may be related to the Flynn effect.

Gaps are seen in other tests of cognitive ability or aptitude, including university admission exams such as the SAT and GRE, as well as employment tests for corporate settings and the military. Measures of school achievement correlate fairly well with IQ, especially in younger children. In the United States, achievement tests find that by 12th grade black students are performing on average only as well as white and Asian students in 8th grade; Hispanic students do only slightly better than blacks. Whether these gaps are narrowing or not is debated.

Cultural or genetic explanation?

Introduction

The most widely accepted view among intelligence researchers is that IQ differences among individuals of the same race reflect real, functionally/socially significant, and substantially genetic differences in the general intelligence factor, g. It is likewise widely believed that average IQ differences among races reflect real and significant differences in the same g factor. While these conclusions are largely beyond technical dispute, the nature of g is still an active area of research.

However, it is a matter of debate whether IQ differences among races in the U.S. are entirely environmental or partly genetic. Several published consensus statements agree that the large difference between the average IQ scores of Blacks and Whites in the U.S. cannot be attributed to biases in test construction, nor can they be explained by simple differences in socio-economic status. These results are further supported when the artificial black-white dichotomy is supplemented with statistics for other ethnicities.

It should be noted that most research has been done in the US and a few other developed nations (see above for worldwide data). That research cannot directly be generalized to the world as a whole. Blacks in the US do not constitute a random sample of the original African population, and environmental conditions differ among nations. IQ tests done in developing countries are likely to have been affected by conditions associated with poverty that are common in the developing world, such as nutritional deficiencies and the impact of diseases (for example, HIV, anemia or chronic parasites) that may affect IQ test scores.

The extent to which the IQ gap is caused by genetic or environmental factors is logically independent of the ability for intervention to reduce the gap. A genetic cause is not necessarily irremediable (e.g. diabetes, myopia, and phenylketonuria) and an environmental cause may not be remediable (e.g. accidents and some diseases). Based in part on this distinction, Template:A(Y)ref argue that determining the extent to which genes or environment cause the IQ gap is unimportant.

Cultural explanations

Although IQ is regarded as being highly heritable, this does not mean that IQ differences between racial groups are necessarily genetic in origin, because estimates of heritability are dependent on a given environment. For example, in schizophrenia, also regarded as being highly heritable, increased rates in second and third generation black immigrants to Western European countries do not seem to be the result of increased genetic susceptibility, but another, as yet unidentified, environmental factor.

Regarding the IQ gaps in the U.S., it has also been suggested that African-American culture disfavors academic achievement and fosters an environment that is damaging to IQ. Likewise, it is argued that the persistence of negative racial stereotypes reinforces this effect. John Ogbu has developed a hypothesis that the condition of being a "caste-like minority" affects motivation and achievement, depressing IQ. Similarly, it's suggested reduced performance from "stereotype threat" could be a contributing factor.

Many anthropologists have argued that intelligence is a cultural category; some cultures emphasize speed and competition more than others, for example. Speculations about innate differences in intelligence between ethnic groups have occurred throughout history. Aristotle in the 4th century B.C. and Cicero in the 1rst. century B.C. disparaged the intelligence of the northern Europeans of the time, as did the Moors in Iberia in the 11th century.

Even proponents of the view that the IQ gap is caused partly by genetic differences recognize that non-genetic factors are likely to be involved.

In the developing world many factors can greatly decrease IQ scores. Examples include nutrition deficiencies in iodine and iron; certain diseases like malaria; unregulated toxic industrial substances like lead and mercury; and poor health care for pregnant women and infants. Also in the developed world there are many non-genetic biological factors that can affect IQ. Increased rates of low birth weight babies and lower rates of breastfeeding in Blacks as compared to Whites are some factors of many that have been proposed to affect the IQ gap. Indeed, one author has compiled a list of over one hundred possible causes of the Black-White IQ gap.

The poorly understood Flynn effect is often cited as evidence that average IQ scores have changed greatly and rapidly, noting that average IQ in the US, after norming to today's standards, may have been below 75 before the start of this effect. This means, given the same test, the mean Black American performance today could be higher than the mean White American performance in 1920, though the gains causing this appear to have only occurred predominantly in the lower half of the IQ distribution. Some therefore argue that the IQ gap among races might change in the future or is even now be changing. On the supposition that the effect started earlier for Whites, because their social and economical conditions began to improve earlier than did those of Blacks, they see even more promise in this hypothesis. However, after analyzing IQ data, one research group concluded that "the gains cannot be explained solely by increases at the level of the latent variables (common factors), which IQ tests purport to measure". In other words, according to this study, some of the inter-generational difference in IQ is attributable to bias or other artifacts, and not real gains in general intelligence or higher-order ability factors, unlike the B-W IQ gap.

A recent theory hypothesizes that fluid cognition (gF') may be separable from general intelligence, and that gF' may be very susceptible to environmental factors, in particular early childhood stress. Some IQ tests, especially those used with children, are poor measures of gF', which means that the effect of the environment on intelligence regarding racial differences, the Flynn effect, early childhood intervention, and life outcomes may have been underestimated in many studies.

Many studies that attempt to test for heritability find results that do not support the genetic hypothesis. They include studies on IQ and skin color, self-reported European ancestry, children in post WWII Germany born to Black and White American soldiers, blood groups, and mixed-race children born to either a Black or a White mother. Many intervention and adoption studies also find results that do not support the genetic hypothesis. Non-hereditarians have argued that these are direct tests of the genetic hypothesis and of more value than indirect variables, such as skull size and reaction time.. Hereditarians argue that these studies are flawed, or that they do support the partly-genetic hypothesis.

Genetic explanations

Arthur Jensen and others have concluded that the IQ gap is substantially genetic. Rushton and Jensen argue that while plausible environmental explanation for the lower mean IQ in Blacks in the U.S. can be offered in many cases, these explanations are less capable of explaining the higher average IQ of East Asians than Whites. Under their interpretation of Lakatos's technical concept of research programs, Jensen and Rushton argue that the culture-only hypothesis is not "progressive" but "degenerating".

To support these claims, they most often cite:

1. worldwide Black–White–East Asian differences in IQ, reaction time, and brain size, with Black-White IQ differences observable in the U.S. at every age above 3 years, within every occupation or socioeconomic level, in every region of the country, and at every time since the invention of ability tests.
2. Race differences are most pronounced on tests that are the best measures of g(see Spearman's hypothesis), which also show the highest heritability, show the highest inbreeding depression scores, and on tests which are the least culturally loaded
3. The rising heritability of IQ with age (within races; on average haritability starts at 20% in infants, rises to 40% in middle childhood, and peaks at 80% in adulthood) and the disappearance (~0.0) by adulthood of shared environmental effects on IQ (for example, family income, education, and home environment), making adopted siblings no more similar in IQ than strangers
4. regression to differing means for different races.

For fuller listings of evidence for the partly-genetic position, see Comparison of interpretations, Template:A(Y)ref, or this press release.

Template:A(Y)ref have concluded that the best explanation is that 50%-80% of the group differences in average IQ is genetic. Other evidence, such as transracial adoption, differing SAT scores even when matched for socioeconomic status and parental education, certain racial admixture studies, "life-history" traits, and evolutionary explanations have also been proposed to indicate a genetic contribution to the IQ gaps and explain how these arose. Critics of this view, such as Robert Sternberg, argue that these studies are either flawed and thus inconclusive, or else that they support the culture-only hypothesis. A 2001 study by Dolan and Hamaker reanalyzed the data from several earlier studies and concluded that Spearman's hypothesis is not an "empirically established fact".

Five recent studies have shown that some genes involved in brain development and other neuronal functions have variants that have spread to high frequencies under selective pressure and now occur in different frequencies in different global populations. The novel variants of microcephalin and ASPM, genes previously implicated in the evolution of human brain size, were found at low frequencies in sub-Saharan African populations, at 70% and 50% in Europeans, 70% and less than 50% in East Asians, and microcephalin at 100% in the tested South American Indian populations. ASPM is estimated to have arisen 500-14,100 years ago, with researchers favouring 5,800 as most likely. Different populations may utilize different variants to respond to similar evolutionary pressures.

Expert opinion

In a 1987 survey of scholars in specialties related to IQ in Education, Psychology, Sociology, and Cognitive Science, given four choices, 52.9% of respondents supported the "partly genetic" position, 1.2% of respondents supported the "entirely genetic" position, 17.7% supported the "entirely environmental" position, and 28.2% responded that there was insufficient data "to support any reasonable opinion". Respondents on average called themselves slightly left of center politically, but political and social opinions accounted for less than 10% of the variation in responses.

According to the APA 1995 task force report, in contrast:

It is sometimes suggested that the Black/White differential in psychometric intelligence is partly due to genetic differences (Jensen, 1972). There is not much direct evidence on this point, but what little there is fails to support the genetic hypothesis.

The APA journal that published the statement, American Psychologist, subsequently published eleven critical responses in January 1997, most arguing that the report failed to examine adequately the evidence for partly-genetic explanations. Charles Murray, for instance, responded:

Actually, there is no direct evidence at all, just a wide variety of indirect evidence, almost all of which the task force chose to ignore.

Coming advances in genetics and genomics are expected to soon provide the ability to test hypotheses about group differences more rigorously than has as yet been possible.

Researchers who believe that there is no significant genetic contribution to race differences in intelligence include Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, and Template:AYref. Some scientists who emphasize cultural explanations do not necessarily exclude a small genetic influence. Template:A(Y)ref suggests up to 20% genetic influence be included in the cultural explanation. Researchers who believe that there are significant genetic contributions to race differences in intelligence include Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, and Template:AYref.

Significance of group IQ differences

See also: Practical importance of IQ

Within societies

There is substantial overlap in the distribution of IQ scores among individuals of each race. Template:A(Y)ref (p. 357) estimates that in a random sample of equal numbers of US Blacks and Whites, most of variance in IQ would be unrelated to race or social class. The average IQ difference between two randomly paired people from the U.S. population, one Black and one White, is approximately 20 points. However, by the same method of calculation, the average difference between two random people is approximately 17 points, and the average difference between two siblings is 12 points.

In essays accompanying the publication of The Bell Curve, Herrnstein and Murray argue that whether the cause of the IQ gap is partly genetic or entirely environmental does not really matter because that knowledge alone would not help to eliminate the gap and that knowledge should not impact the way that individuals treat one another. They argue that group differences in intelligence ought not to be treated as more important or threatening than individual differences, but suggest that one legacy of Black slavery has been to exacerbate race relations such that Blacks and Whites cannot be comfortable with group differences in IQ or any other traits.

Moreover, although it may appear paradoxical, a goal of social egalitarianism is to raise the genetic contribution to intelligence to as high as possible, by minimizing environmental inequalities and any negatively IQ-impacting cultural differences (The Blank Slate, 106-107). If such conditions were achieved, any remaining group (but not individual) IQ differences would then be 100% hereditary: the only remaining factor that could potentially contribute to race-based outcome differences.

The appearance of a large practical importance for intelligence makes some scholars claim that the source and meaning of the IQ gap is a pressing social concern. The IQ gap is reflected by gaps in the academic, economic, and social factors correlated with IQ. However, some dispute the general importance of the role of IQ for real-world outcomes, especially for differences in accumulated wealth and general economic inequality in a nation. See "Practical importance of IQ".

Two statistical effects interact to exacerbate group IQ differences. First, there seem to be minimum statistical thresholds of IQ for many socially valued outcomes (for example, high school graduation and college admission). Second, because of the shape of the normal distribution, only about 16% of the population is at least one standard deviation above the mean. Thus, although the IQ distributions for Blacks and Whites are largely overlapping, different IQ thresholds can have a significant impact on the proportion of Blacks and Whites above and below a particular cut-off.

Small differences in IQ, while relatively unimportant at the level of an individual, would theoretically have large effects at a population level. Template:A(Y)ref calculate that a 3-point drop in average IQ would have little effect on factors like marriage, divorce, or unemployment. However, the drop from IQ 100 to 97 would increase poverty rates by 11 percent and the proportion of children living in poverty by 13 percent. All else being equal, similar rises would occur in rates of children born to single mothers, men in jail, high school drop-out, and men prevented from working due to health-related problems. In contrast, if average IQ were to increase 3-points to 103, poverty rates would fall 25 percent, children living in poverty would fall 20 percent, and high school drop-out rates would fall 28 percent.

Studies from The Bell Curve and elsewhere indicate that controlling for IQ narrows, eliminates, or even reverses the Black-White gap in social and economic factors associated with IQ. After controlling for IQ, the probability of having a college degree or working in a high-IQ occupation is higher for Blacks than Whites. Controlling for IQ shrinks the income gap from thousands to a few hundred dollars. Controlling for IQ cuts differential poverty by about three-quarters and unemployment differences by half. However, controlling for IQ has little effect on differential marriage rates. For many other factors, controlling for IQ eliminates the differences between Whites and Hispanics, but the Black-White gap remains (albeit smaller).

Another study found that wealth, race and schooling are important to the inheritance of economic status, but IQ is not a major contributor and the genetic transmission of IQ is even less important.

Whites are not a homogeneous group regarding real-world outcomes. For example, in the U.S. 33.6% of persons with self-reported Scottish ancestry completed college, while only 16.7% of persons with self-reported French-Canadian ancestry have done so.

For additional discussion of the effects of controlling for group differences on a variety of outcomes and groups, see Template:AYref, and Template:AYref.

Between nations

Some people have attributed differential economic growth between nations to differences in the intelligence of their populations. One example is Richard Lynn's IQ and the Wealth of Nations. The book, is sharply criticized in the peer-reviewed paper The Impact of National IQ on Income and Growth. Another peer-reviewed paper, Intelligence, Human Capital, and Economic Growth: An Extreme-Bounds Analysis, finds a strong connection between intelligence and economic growth. It has been argued that East Asian nations underachieve compared to IQ scores. One suggested explanation is that verbal IQ is more important than visuospatial IQ.

Jared Diamond's Guns, Germs and Steel instead argues that historical differences in economic and technological development for different areas can be explained by differences in geography (which affects factors like population density and spread of new technology) and differences in available crops and domesticatable animals. However, these environmental differences may operate in part by selecting for higher levels of IQ

For high-achieving minorities

The book World on Fire notes the existence in many nations of minorities that have created and control a disproportionate share of the economy, a market-dominant minority. Examples include Chinese in Southeast Asia; Whites, Indians, Lebanese and Igbo people of Western Africa; Whites in Latin America; and Jews in pre-World War II Europe, modern America, and modern Russia. These minorities are often resented and sometimes persecuted by the less successful majority.

In the United States, Jews, Japanese, and Chinese earn incomes 1.72, 1.32, and 1.12 times the American average, respectively (Sowell, 1981, p. 5). Jews and East Asians have higher rates of college attendance, greater educational attainment, and are many times overrepresented in the Ivy League and many of the United States' most prestigious schools, even though affirmative action discriminates against Asians in the admissions process (relative to Whites as well as to other minorities). At Harvard, for example, Asian American and Jewish students together make up 51% of the student body, though only constituting roughly 6% of the US population. In various Southeast Asian nations, Chinese control a majority of the wealth despite being a minority of the population and are resented by the majority, in some cases being the target of violence.

Achievement in science, a high-complexity occupation in which practitioners tend to have IQs well above average, also appears consistent with some group IQ disparity. Only 0.25% of the world population is Jewish, but Jews make up an estimated 28% of Nobel prize winners in physics, chemistry, medicine, and economics. In the U.S., these numbers are 2% of the population and 40% of winners. A significant decline in the number of Nobel prizes awarded to Europeans, and a corresponding increase in the number of prizes awarded to US citizens, occurred at the same time as Nazi persecutions of Jews during the 1930s and the Holocaust during the 1940s.

Groups vary significantly in their IQ subtest profiles. Ashkenazi Jews, for example, demonstrate verbal and mathematical scores more than one standard deviation above average, but visuospatial scores roughly one half standard deviation lower than the White average, whereas East Asians demonstrate high visuospatial scores, but average or slightly below average verbal scores. Concordantly, the professions in which these populations tend to be over-represented differ . The Asian pattern of subtest scores is found in fully assimilated third-generation Asian Americans, as well as in Inuits and Native Americans (both of Asian origin).

Policy implications

See also: Intelligence and public policy

The public policy implications of IQ and race research are possibly the greatest source of controversy surrounding this issue. For example, the conservative policy recommendations of Herrnstein and Murray in The Bell Curve were denounced by many. Indeed, even proponents of a partly genetic interpretation of the IQ gap, such as Template:A(Y)ref and Template:A(Y)ref, argue that their interpretation does not in itself demand any particular policy response: while a conservative/libertarian commentator may feel the results justify reductions in affirmative action, a liberal commentator may argue from a Rawlsian point of view (that genetic advantages are undeserved and unjust) for substantial affirmative action. According to the "Mainstream Science on Intelligence"; statement published in the Wall Street Journal in 1994:

The research findings neither dictate nor preclude any particular social policy, because they can never determine our goals. They can, however, help us estimate the likely success and side-effects of pursuing those goals via different means.

While not specifically race-related, policies focused on geographical regions or nations may have disproportionate influences on certain racial groups and on cognitive development. Differences in healthcare, nutrition, regulation of environmental toxins, and geographic distribution of diseases and control strategies between the developing world and developed nations have all been subjects of policies or policy recommendations (see health and nutrition policies relating to intelligence).

Finally, germinal choice technology may one day be able to select or change directly alleles found to influence intelligence or racially identifying traits (such as skin color; see gene SLC24A5), making them susceptible to biotechnological intervention.

End material

Notes

1. Researchers contributing to this area of inquiry mostly include psychologists, psychometricians, geneticists, sociologists, and anthropologists.
2. Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref. For samples of individual studies showing similar results, see the National Collaborative Perinatal Project, reported by Template:AYref; the Minnesota Transracial Adoption Study reported by Template:AYref; also Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref; Template:AYref; Template:AYref Template:AYref; Template:AYref, Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref. For scientific consensus statements see Template:AYref and Template:AYref.
3. Other clustering: Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref; Template:AYref, Template:AYref; Template:AYref; Template:AYref. The East-Asian/White/Black difference in average IQ can be measured in very young children. For example, a one standard deviation gap is observed in Black and White 3-year olds matched for gender, birth order, and maternal education (Template:AYref). Template:AYref found that by age 6 the average IQ of East Asian children is 107, 103 for White children and 89 for Black children. Template:A(Y)ref found that the same trichotomy in brain size and IQ held at 4 months, 1 year, and 7 years of age.
4. For this calculation, Herrnstein and Murray alter the mean IQ (100) of the U.S. National Longitudinal Survey of Youth's population sample by randomly deleting individuals below an IQ of 103 until the population mean reaches 103. This calculation was conducted twice and averaged together to avoid error from the random selection.(Template:AYref, pp. 364-368) Discussed further in the section #Significance of group IQ differences #Within societies.
5. Whether or not this carries over to adulthood remains to be investigated.
6. Template:AYref, Template:AYref (given in Template:AYref's summary, p.599)
7. Template:AYref, Template:AYref (given in Template:AYref's summary, p. 599)
8. It is well established that within-population genetic diversity is greatest within Sub-Saharan Africa, and decreases with distance from Africa. One study estimates that only 6.3% of the total human genetic diversity is explained by race. This value is comparable to other reports which find that on average approximately 85% of genetic variation occurs within populations. In a hypothetical situation with two populations and a single gene with two alleles, this is equivalent to allele frequencies of 30% + 70% in one population and 70% + 30% in the other. Thus, using this single gene to classify individuals into populations would result in a 30% misclassification rate.
9. Template:AYref, Template:AYref, Template:AYref, Template:AYref, . Lewontin, for example argues that there is no biological basis for race on the basis of research indicating that more genetic variation exists within such races than between them Template:AYref.
   
   Some critics of race may not consider this a problem for race and intelligence inquiries. Jared Diamond, who praises Cavalli-Sforza's genetics research over the decades for "demolishing scientists' attempts to classify human populations into races in the same way that they classify birds and other species into races"(Template:AYref), also argues "in mental ability New Guineans are probably genetically superior to Westerners" due to that intelligence was likely selected for in hunter-gatherer New Guinea societies where the challenges were tribal warfare and food procurement, compared with high population density European civilizations where the major survival pressure was on genes for resisting epidemics (Diamond 1997/99, p.21).
10. Template:AYref, Template:AYref. Neil Risch argues: "One could make the same arguments about sex and age! . . you can undermine any definitional system. . . In a recent study. . . we actually had a higher discordance rate between self-reported sex and markers on the X chromosome between genetic structure versus self-description, 99.9% concordance. . . So you could argue that sex is also a problematic category. And there are differences between sex and gender; self-identification may not be correlated with biology perfectly. And there is sexism. And you can talk about age the same way. A person's chronological age does not correspond perfectly with his biological age for a variety of reasons, both inherited and non-inherited. Perhaps just using someone's actual birth year is not a very good way of measuring age. Does that mean we should throw it out? . . . Any category you come up with is going to be imperfect, but that doesn't preclude you from using it or the fact that it has utility" (Template:AYref).
11. Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref: "If enough markers are used... individuals can be partitioned into genetic clusters that match major geographic subdivisions of the globe".
12. Template:AYref
13. ^ Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref. The neural dopamine gene studied in Harpending and Cochran, previously found to occur in substantially different worldwide frequencies, is also tied to behavior, with bearers displaying greater novelty-seeking behavior and being at increased risk for attention-deficit hyperactivity disorder. Harpending and Cochran suggest this gene "may be a model system for understanding the relationship between genetic variation and human cultural diversity," noting high frequencies in South American Indians, such as the Yanomamo (sometimes referred to as "the Fierce People"), intermediate frequencies in Europeans and Africans, and very low frequencies in East Asians and !Kung Bushmen (sometimes referred to as "the Harmless People"). Template:AYref, another study discussing behavioral variation, finds significantly higher behavioral inhibition in native German children with blonde hair, and slightly higher inhibition in American caucasian children with blue eyes, compared with a statistically insignificant increase in inhibition in German children with blue eyes.
    
    See the NYTimes' "Researchers Say Human Brain Is Still Evolving" (September 8, 2005), and "Still Evolving, Human Genes Tell New Story" (March 7, 2006) for discussion of Mekel-Bobrov et al. and Evans et al., and Voight et al.
14. Template:AYref
15. Template:AYref; Template:AYref
16. Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref
17. Template:AYref
18. Template:AYref; Template:AYref, pp. 45–54
19. Template:AYref pp. 67–69
20. Template:AYref
21. Template:AYref
22. Template:AYref
23. Template:AYref
24. Template:AYref. (Snyderman and Rothman do not work in race and intelligence.)
25. The proportion of experts supporting these hypotheses today is unknown. Prominent critic Robert Sternberg defended the minority view as such in 1995, stating "science isn't done by majority rule." Critic Reginald Wilson states in 1992 "Although we may believe that we live in an enlightened age, most of my colleagues believe indeed that there are substantial genetic components to the lower IQ scores that are on average earned by African-Americans and by Hispanics compared to whites and Asians. And that has been substantiated by surveys of them and of the leading experts in the field" (Template:AYref).
26. Template:AYref: "One is that misinterpretation of research is regrettably all too common and thus that documenting misinterpretations in one single domain is of limited interest. Our response is that we are singling out this domain because the issue at stake is of such importance and because the interpretive errors are so rampant and so systematic" (p. 11).
27. Other researchers have extended these results to other groups (e.g., gender, age) (p. 11).
28. pp. 10-11.
29. "We can only speculate as to causes of the mischaracterization of the Steele and Aronson (1995) findings in these various media. . . A factor contributing to not noticing the adjustment may be the appeal of the misinterpreted findings (i.e., the conclusion that eliminating stereotype threat eliminates African American–White differences). Finding mechanisms to reduce or eliminate subgroup differences is an outcome that we believe would be virtually universally welcomed. Thus, research findings that can be interpreted as contributing to that outcome may be more readily accepted with less critical scrutiny" (p. 11).
30. Template:AYref. The position that knowledge of what is is dependent on statements of what is good has been criticized by microbiologist Bernard Davis as the "moralistic fallacy," an implied converse of the naturalistic fallacy(Template:AYref). The latter refers to an effort to derive an ought directly from an is (for example, war is good because it's part of human nature) and the former refers to an effort to derive an is from an ought (for example, war is not part of human nature because it's bad).
31. "...Might it be fair also to say that the champions of 'no difference' in race or sex, or intelligence ... are the guardians of a greater 'untruth' that allows people to live together in mutual harmony, implying that these critics really deserve to be praised as our protectors even when they are factually wrong? ... I think also it is roughly how the self-appointed guardians choose to present themselves - leaving aside, usually, the step of frankly admitting that they are promoting factual untruths when they know that they are." While these scientists may, he argues, be driven by personal social or political concerns, "it is harder for me to caste a man like Philipe Rushton, taking an example from the other side, in a similar light. ... Rushton has to be admitted to be promoting a segment of the pan-human chromosome that is very distantly situated from his own locus, Ontario, supporting a locus situated at the far end of Asia." Hamilton concludes: "Any human science not aiming for factual truth in human social matters is as inevitably doomed to bring costly accidents in the long run as would be an unfactual science of technology" (Template:AYref, pp. 332-334)
32. Dawkins 2000
33. Template:AYref
34. The Blank Slate p. 145
35. Template:AYref
36. Template:AYref predicts "the dangerous idea of the next decade that groups of people may differ genetically in their average talents and temperaments . . . Perhaps geneticists will forbear performing these tests, but one shouldn't count on it. The tests could very well emerge as by-products of research in biomedicine, genealogy, and deep history which no one wants to stop." Template:AYref argues "We will have to consider how much our genes shape personality, intelligence, athletic talent, musical ability, memory, temperament, sexual orientation such sensitive issues will not remain in limbo much longer . . . The answers will be just another byproduct of to find useful correlations between our genes and key aspects of who we are. How we respond to this new information will be one of the biggest social and intellectual challenges of the coming decades, for we will learn a great deal about ourselves that many people would rather not face" (pp. 44-47, also p. 105). Template:AYref discusses the issue of group differences also in the context of age groups and sexual orientation groups.
37. http://www.tolerance.org/maps/hate/index.html.
38. Ulric Neisser, who was the chairman of the APA's 1995 taskforce on intelligence research, gave support for Richard Lynn's argument in Lynn's The Science of Human Diversity: A History of the Pioneer Fund (2001). Neisser states in his book review (Template:AYref) that, though race and intelligence research "turns stomach . . . Lynn's claim is exaggerated but not entirely without merit: 'Over those 60 years, the research funded by Pioneer has helped change the face of social science.'" Neisser concludes in agreement with Lynn and against William Tucker's critical book on the Pioneer Fund (Template:AYref), also reviewed, that the world is ultimately better off having had the Pioneer Fund: "Lynn reminds us that Pioneer has sometimes sponsored useful research - research that otherwise might not have been done at all. By that reckoning, I would give it a weak plus."
39. Template:AYref
40. Template:AYref
41. Template:AYref, Template:AYref. Template:AYref summarizes the history of harrassment and violence in this area: "For a long time Jensen received death threats, needed body guards while on his campus or others, had his home and office phones routed through the police station, received his mail only after a bomb squad examined it, was physically threatened or assaulted dozens of times by protesters disrupting his talks in the United States and abroad, regularly found messages like "Jensen Must Perish" and "Kill Jensen" scrawled across his office door, and much more. Psychologists Richard Herrnstein and Hans Eysenck also had such experiences during the 1970s for defying right thinking about intelligence—Eysenck, for example, being physically assaulted by protesters during a public lecture at the London School of Economics."
42. For example, see Template:AYref; Template:AYref; Template:AYref
43. See two examples in Template:AYref and Template:AYref above.
44. Template:AYref p. 11
45. Template:AYref p. 79.
46. Sociologist Thomas Volken argues the IQ and the Wealth of Nations data for national IQs is "highly deficient," citing limited sampling and varying tests and years (Volken). In a 1995 review of The Bell Curve, controversial critic Leon Kamin writes that "Lynn's distortions and misrepresentations of the data constitute a truly venomous racism, combined with scandalous disregard for scientific objectivity."(Template:AYref). In contrast to Kamin's strongly worded attack on Lynn, W. D. Hamilton described Lynn in a review of another of Lynn's books as doing "an excellent job with the facts" and being "brave thick-skinned ... to swim against ... popular antirealistic currents."
    
    Examples of problematic national IQ figures include that the stated average IQ score of 59 for Equatorial Guinea is based on one test of 48 children aged 10-14 in 1984; the Ethiopian average is derived from a study of Ethiopians who immigrated to Israel a year prior, and whose low scores were thought by the original authors to be a reflection of temporary adjustment to a different culture and language (note that this data is not used in the averages presented below). Kamin also argued Lynn selectively excluded data showing a similar score in Whites and sub-Saharan Africans: "Lynn chose to ignore the substance of Crawford-Nutt's paper, which reported that 228 black high school students in Soweto scored an average of 45 correct responses on the Matrices--HIGHER than the mean of 44 achieved by the same-age white sample on whom the test's norms had been established and well above the mean of Owen's coloured pupils." (Template:AYref)
47. Template:AYref;Template:AYref
48. Template:AYref
49. Template:AYref
50. Template:AYref
51. Template:AYref
52. Template:AYref
53. see Template:AYref, p. 80 for a consensus statement
54. see Race and intelligence (Average gaps among races)#Reaction time
55. Template:AYref, Template:AYref; Template:AYref, Template:AYref
56. Template:AYref
57. Template:AYref; Template:AYref; Template:AYref; Template:AYref
58. See for example Template:AYref
59. Murry and Herrnstein argue that it would not be good to learn that the gap were predominantly environmental nor bad to learn that the gap were predominantly genetic. Instead, they argue that that what matters is how hard the gap is to change. They argue that the history of attempts to reduce the gap through environmental intervention have produced no definitive, lasting results. As such, even if the gap were entirely environmental, we would be no closer to changing it. They also argue that knowing whether the gap is genetic or environmental should not affect how individuals treat one another. First, because individuals should be treated as individuals rather than as groups. Second, because the reality of the gap is independent of the cause of the gap (that is, it would make no difference to learn that the gap were "only" caused by the environment.
60. Template:AYref
61. Template:AYref; Template:AYref. See Template:AYref, pp. 511-512 for a critique of these arguments.
62. Template:AYref found that making race salient when taking a test of cognitive ability negatively affected high-ability African American students. They name this phenomenon stereotype threat. Template:AYref point out that these findings are widely misinterpreted to mean that eliminating stereotype threat eliminated the Black-White performance gap. See also Template:AYref, Template:AYref, Template:AYref and Template:AYref for discussion of the implications of stereotype threat for race and intelligence research.
63. Aristotle: "Having spoken of the number of the citizens, we will proceed to speak of what should be their character. This is a subject which can be easily understood by any one who casts his eye on the more celebrated states of Hellas, and generally on the distribution of races in the habitable world. Those who live in a cold climate and in Europe are full of spirit, but wanting in intelligence and skill; and therefore they retain comparative freedom, but have no political organization, and are incapable of ruling over others. Whereas the natives of Asia are intelligent and inventive, but they are wanting in spirit, and therefore they are always in a state of subjection and slavery. But the Hellenic race, which is situated between them, is likewise intermediate in character, being high-spirited and also intelligent. Hence it continues free, and is the best-governed of any nation, and, if it could be formed into one state, would be able to rule the world. ” (Aristotle, Politics, ch. 7).
    Cicero: “Do not obtain your slaves from Britain because they are so stupid and so utterly incapable of being taught that they are not fit to form a part of the household of Athens.” Attributed to Cicero's Epistulae ad Atticum (Letters to Atticus), 68 BC-43 BC (latin text). Translation: Template:AYref.
    "Races north of the Pyrenees are of cold temperament and never reach maturity; they are of great stature and of a white colour. But they lack all sharpness of wit and penetration of intellect." Attributed to "Said of Toledo (a Moorish savant)" by Template:AYref (p.34), originally quoted in Template:AYref.
64. See Race and intelligence (Culture-only or partially-genetic explanation)#Nongenetic biological factors
65. Template:AYref
66. (Template:AYref)
67. Template:AYref
68. Template:AYref
69. Template:AYref
70. Template:AYref, Template:AYref
71. Template:AYref
72. Template:AYref
73. Template:AYref argue that these studies are "peculiarly old, the mean year of publication being 1960" and "actually very weak and nondecisive, not having been replicated even once". Template:AYref, for example, points out that while the study of children born in post-WWII Germany finds no difference between white and interracial children, it does find a large difference in IQ between boys and girls, suggesting that sampling artifacts have affected the results.
74. Template:AYref
75. For example, see Template:AYref
76. Template:AYref
77. Template:AYref
78. Template:AYref, cited in "Black-White-East Asian IQ differences at least 50% genetic, scientists conclude in major law journal", and Template:AYref
79. Template:AYref. Critics accept the results of this survey. Robert Sternberg, for example, defends the minority view, stating "science isn't done by majority rule" (1995).
80. Murray lists race differences in brain size, along with "IQ in sub-Saharan Africa, the results of transracial adoption studies, the correlation of the black-white difference with the g-loadedness of tests, regression to racial means across the range of IQ, or other relevant data" among the evidence omitted from the task force report.
81. Template:AYref, Template:AYref pp. 44-47.
82. Equal-sized random samples of children from California schools were used for this analysis. Social class was rated on a ten-point scale based on parents' education and occupation. Only 30% of total variance in IQ is associated with differences between race and social class, whereas 65% exists within each racial and social class group. The single largest source of IQ variance exists between siblings within the same family.
83. Template:AYref, Template:AYref
84. Template:AYref; Template:AYref
85. ^ The criteria for the "Middle-Class Values" index were: (for men) obtained high school degree (or more), were in labor force (but could be unemployed) throughout previous year (1989), never incarcerated, were still married to their first wife; (for women) obtained a high school degree, had never given birth out of wedlock, never incarcerated, were still marreid to their first husband. Individuals unable to work and those still in school were excluded from this analysis, as well as never-married individuals who satisfied all the other criteria. Poverty is not a criterion, nor is having children.
86. Template:AYref. Note that race, schooling and IQ are all correlated, so considering them as separate factors lessens the apparent effect of IQ.
87. these values were taken from Template:AYref, which reprints U.S. Census data which was originally reported by Template:AYref, p. 105. Template:AYref challenges the factual accuracy of other reporting by Template:AYref.
88. Thomas Volken, "The Impact of National IQ on Income and Growth."
89. Template:AYref
90. Template:AYref
91. Richard Nisbett argues in his 2004 The Geography of Thought that some of these regional differences shaped lasting cultural traits, such as the collectivism required by East Asian rice irrigation, compared with the individualism of ancient Greek herding, maritime mercantilism, and money crops wine and olive oil (pp. 34-35).
92. This theory is discussed by Template:AYref (pp. 435-437), Template:AYref and Template:AYref in general and by Steve Sailer with respect to Guns, Germs, and Steel. See Race and intelligence (Culture-only or partially-genetic explanation)#Rushton's application of r-K theory. .. Template:AYref state generally that "a number of recent studies have detected more signals of adaptation in non-African populations than in Africans, and some of those studies have conjectured that non-Africans might have experienced greater pressures to adapt to new environments than Africans have" (Template:AYref, Template:AYref, Template:AYref, Template:AYref, Template:AYref).
93. Template:AYref, pp. 7, 93
94. A study by Princeton researchers Template:AYref analyzes the effects of admission preferences at elite universities in terms of SAT points (1600-point scale): Blacks +230; Hispanics +185; Asians −50; Recruited athletes +200; Legacies (children of alumni) +160. "Our results show that removing consideration of race would have a minimal effect on white applicants to elite universities. The number of accepted white students would increase by 2.4%." Asian percent of accepted students, in contrast, would increase by 33% (from 23.7% to 31.5%). "Nearly four out of every five places in the admitted class not taken by African-American and Hispanic students would be filled by Asians."
95. Template:AYref
96. Template:AYref, pp. 133-134; Template:AYref
97. Template:AYref
98. Template:AYref
99. Template:AYref, p. 4
100. Lynn, , Template:AYref, p.178)
101. Template:AYref
102. Template:AYref
103. Template:AYref
104. Template:AYref
105. Gregory Stock argues "current debates about whether some of the differences among ethnic and racial groups are cultural or biological will soon become irrelevant, given the coming " (Template:AYref, p. 194; race and intelligence discussed on pp. 44-47).

See also

• Brain to body mass ratio
• Craniometry
• Hominid intelligence
• Neuroscience and intelligence
• Race and crime
• Sex and intelligence
• Scientific racism

References

External links

Collective Statements

• The Wall Street Journal: Mainstream Science on IntelligencePDF
• APA Task Force Examines the Knowns and Unknowns of Intelligence
• Statement on "Race" and Intelligence. American Anthropological Association. Adopted December 1994.

Review Papers

• June 2005 issue of Psychology, Public Policy, and Law, Vol. 11, No. 2.
  • Thirty Years of Research on Race Differences in Cognitive Ability J. Philippe Rushton & Arthur R. Jensen
  • There Are No Public-Policy Implications Robert J. Sternberg
  • What if the Hereditarian Hypothesis is True? Linda S. Gottfredson
  • Heredity, Environment, and Race Differences in IQ Richard E. Nisbett
  • The Cultural Malleability of Intelligence and Its Impact on the Racial/Ethnic Hierarchy Lisa Suzuki & Joshua Aronson
  • Wanted: More Race Realism, Less Moralistic Fallacy J. Philippe Rushton & Arthur R. Jensen
• Race, Genetics and IQ Richard E. Nisbett (PDF)
• The Inequality Taboo Charles Murray
• The Black-White Test Score Gap (1998) online (page-image) version of ISBN 0815746091

Others

• Resurrecting Racism: The modern attack on black people using phony science. Historical and Investigative Research Francisco Gil-White 2005.
• Crippled by Their Culture - Race doesn't hold back America's black rednecks. Nor does racism by Thomas Sowell
• Race and IQ: Part 1, Part 2, Part 3 by Thomas Sowell
• The Skeptic's Dictionary entry on IQ and race
• Criticism on source material of Bell Curve book
• Poverty and Brain Development in Early Childhood 1999 report
• Miscellaneous articles by Richard Lynn et al.
• Are IQ Tests Biased?
• Scholars Provide an Overview of Explanations for Black-White Test Score Gap
• School Readiness: Closing Racial and Ethnic Gaps
• Variation in IQ, Brain Capacity, Size and Density by Race
• La Griffe du Lion - pseudonymously released statistical analyses on this and related subjects. (Review)
• Are all races equally intelligent? -- Or: When is knowledge knowledge? by John J. Ray
• A review of the field (Jan. 2006) Kohn, Marek, "This racist undercurrent in the tide of genetic research: As taboos fall away, there's a danger that denial of racial difference will be replaced with uncritical acceptance," The Guardian.
• "Jews on Jews: Jews are Great," Seed Magazine

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