Race and intelligence is a controversial, interdisciplinary field 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:
Many hypotheses have been proposed to explain racial-ethnic group differences in IQ. Certain environmental factors, such as childhood Nutrition, are known to modulate IQ, 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. Media portrayal of the role of genetic and environmental factors in explaining individual and group differences in IQ has itself been studied and shown to be misleading regarding mainstream expert opinion. 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. Critics often fear the misuse of the research, question its Utility, feel that comparing the intelligence of racial groups is itself unethical, or fear sociopolitical ramifications, whether justified or unjustified. 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 intelligence, and the hypothesis that a genetic component may be involved, have led to heated academic debates that have spilled over into the public sphere.
Within this context, races are defined by geographic ancestry. For example, the category Black refers to people who have most of their ancestry in sub-Saharan Africa, rather than to people with dark skin. The racial labels used by scientific researchers in the United States 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 (Tang et al., 2005). 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 countries on the western side of the Pacific Rim. Hispanics, more often called an Ethnic group rather than a race, form a genetically diverse group that includes many recent U.S. immigrants of mixed ancestry.
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.
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). In this article, "IQ test" denotes any test of cognitive ability, and "IQ" is used as a 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. Criticisms of the validity of IQ testing focus primarily on questions of "test bias", which has many related meanings. Several conclusions about tests of cognitive ability are now largely accepted:
See the articles Intelligence, IQ, and General intelligence factor for further discussion of the validity of these tests.
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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[:Race and intelligence}}#endnote_brain-size-historical]. 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.
Eugenics was later adopted by the Nazi party as a justification for the systematic elimination of "parasitic" races such as Jews and Gypsies. (Note that the Ashkenazi Jewish population has significantly higher average IQ scores than other Whites, usually approximated to be one standard deviation from the mean of other Whites.)
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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.
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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 Gould updated The Mismeasure of Man in 1996, criticizing many aspects of IQ research.
In 2005, 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" (Rushton & Jensen, 2005).
Some scientists, such as evolutionary biologist Stephen Jay Gould, criticize the IQ test as a measure of intelligence, citing what they perceive as inherent racial and social biases as well as systematic flaws in the testing process. Gould's book The Mismeasure of Man is a comprehensive presentation of this argument.
Some critics hold that it is racist to consider the possibility of cognitive or behavioral differences between ethnic groups. Stephen Pinker argues that opposition to racism is based on moral, not on scientific assumptions: "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..." (The Blank Slate, p. 145).
The position that what is good bears on inquiries into what is, or efforts to derive an is from an ought, have been criticized by Bernard Davis as the moralistic fallacy, an implied converse of the Naturalistic fallacy. (Davis 1978) Some researchers in the field of race and intelligence, such as Linda Gottfredson, argue that suppressing race and intelligence research is actually more harmful:
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. (Gottfredson 2005b)
Many critics of the partially genetic hypothesis have criticized the source of much of the funding for researchers supporting this hypothesis, the Pioneer Fund ( ). Defenders argue that standards of evaluating scientific research require that researchers receiving grants be judged only on the scientific merits of their research.
Many of the researchers supporting the partially-genetic explanation of the racial IQ disparity, like the IQ researcher and current head of the fund J. Philippe Rushton, have received grants of varying sizes from the Pioneer Fund. In accord with the tax regulations governing nonprofit corporations, Pioneer does not fund individuals; under the law only other nonprofit organizations are appropriate grantees. As a consequence, many of the fund's awards go not to the researchers themselves but to the universities that employ them, a standard procedure for supporting work by academically based scientists. However, in addition to these awards to the universities where its grantees are based, Pioneer has also made a number of grants to other nonprofit organizations, essentially dummy corporations created solely to channel Pioneer's resources directly to a particular academic recipient. William H. Tucker suggests this is "a mechanism apparently designed to circumvent the institution where the researcher is employed" .
Although the fund typically gives away more than half a million dollars per year, there is no application form or set of guidelines. Instead an applicant merely submits "a letter containing a brief description of the nature of the research and the amount of the grant requested." There is no requirement for peer review of any kind; Pioneer's board of directors—two attorneys, two engineers, and an investment broker—decides, sometimes within a day, whether a particular research proposal merits funding. Once the grant has been made, there is no requirement for an interim or final report or even for an acknowledgment by a grantee that Pioneer has been the source of support, all atypical practices in comparison to other organizations that support scientific research .
The Southern Poverty Law Center (SPLC), an anti-racism organization, lists the Pioneer Fund as a "Hate group," citing its funding of some racist organizations and individuals, and the funding of race and intelligence research.. However, the SPLC itself has been accused of exaggerating the threat of racism in order to increase fund-raising revenue and of wrongfully applying the term "hate group" to legitimate organizations. In 1994, a Pulitzer Prize winning investigative report of the SPLC found evidence of racial discrimination and finanical impropriety.
Supporters of race and intelligence research have accused other scientists of suppressing scientific debate for political purposes. Behavioral geneticist Glayde Whitney argued in his controversial 1995 presidential address to the Behavior Genetics Association that suppression of debate on both individual and group hereditary differences has occurred as a result of a larger ideology of "environmental determinism for all important human traits ... [a] 'Marxist-Lysenkoist' denial of genetics."
Scientists who openly support the hereditary hypothesis have in a number of occurrences faced harassment and interference with their work or funding. Critic of Race science William H. Tucker considers these events to be unjustified, "intolerable violation of academic freedom” (). When J. Phillipe Rushton was being censured by superiors at his University of Western Ontario in 1989 "despite," as Tucker notes, "being the recipient of a prestigious Guggenheim Fellowship and having one of the most productive records of peer-reviewed publication in his department," even notable scientists who had criticized his work, such as James Flynn and Jack Block, wrote to the university on his behalf ().
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. Attempted world-wide compilations of average IQ by race generally place Ashkenazi Jews at the top, followed by East Asians, Whites, Arabs, other Asians, Indians, Blacks and Australian Aborigines.
See IQ and the Wealth of Nations for an attempted compilation of average IQ for different nations and a discussion of associated measurement problems. The IQ scores vary greatly among different nations for the same group. Blacks in Africa score much lower than Blacks in the US. Some reports indicate that the Black–White gap is smaller in the UK than in the U.S. Many studies also show large differences in IQ between different groups of Whites. For example, in Northern Ireland the IQ gap between Protestants and Catholics is as large as that between Blacks and Whites in the US. In Israel, large gaps in test scores and achievement separate Ashkenazi Jews from other groups such as the Sephardi ().
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 the gaps are narrowing or not is debated.
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 just by simple differences in socio-economic status.
It should be noted that most research has been done in the US and a few other developed nations. 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 (e.g., HIV, anemia or chronic parasites) that may affect IQ test scores.
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Many anthropologists have argued that intelligence is a cultural category; some cultures emphasize speed and competition more than others, for example. 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. Non-genetic biological factors that affect IQ have been proposed. 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.
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, 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 (). Hereditarians argue that these studies are flawed and thus inconclusive or that they do support the partly-genetic hypothesis.
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 may have been below 75 before the start of this effect. Some argue that the IQ gap among races might change in the future or is even now 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.
Some scientists who emphasize cultural explanations do not necessarily exclude a small genetic influence. Reynolds (2000) suggests up to 20% genetic influence be included in the cultural explanation.
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 at age 3 in the U.S.; (2) race differences are most pronounced on tests that are the best measures of g, which also show the highest heritability (see Spearman's hypothesis); and (3) the rising heritability of IQ with age (within races; on average 20% heritability in infants, 40% in middle childhood, and 80% in adulthood) and the disappearance (~0.0) by adulthood of shared environmental effects on IQ (e.g., family income, education, and home environment), making adopted siblings no more similar in IQ than strangers (). Rushton and Jensen (2005) have concluded that the differences are at least 50% genetic.
Evidence, such as transracial adoption, certain racial admixture studies, "life-history" traits, and evolutionary explanations have been proposed to indicate a genetic contribution to the IQ gap. Critics of this view, such as Robert Sternberg, argue that these studies are flawed and thus inconclusive or that they support the culture-only hypothesis, and suggest that a definite answer may not be possible until intelligence is directly linked to specific genes.
In a 1987 survey of scholars in specialties related to IQ, 1% or respondents supported the entirely genetic position, 53.1% of respondents supported the partly genetic position, 17.7% supported the entirely environmental position, and 28.2% responded that there was insufficient data "to support any reasonable opinion" (Snyderman & Rothman, 1987). 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.
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.
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 (Gordon 1997; Gottfredson 1997). 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 the "Practical importance of IQ" link above.
Two statistical effects interact to exacerbate group IQ differences. First, there seem to be minimum statistical thresholds of IQ for many socially valued outcomes (e.g., 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.
| | IQ range | Whites | Blacks | Black:White ratio | Training prospects | High school dropout | Lives in poverty |
|---|---|---|---|---|---|---|---|
| <75 | 3.6% | 18.0% | ~5:1 | simple, supervised work; eligible for government assistance | 55% | 30% | |
| <90 | 21.9% | 59.4% | ~2:1 | very explicit hands on training; IQ >80 for military training; no government assistance | 35% | 16% | |
| >100 | 53.8% | 15.7% | ~1:3 | written material plus experience | 6% | 6% | |
| >110 | 27.9% | 3.8% | ~1:7 | college format | 0.4% | 3% | |
| >125 | 5.4% | 0.2% | ~1:32 | independent, self-teaching | 0% | 2% | |
| Based on Wechsler Adult Intelligence Scale IQs for Whites (mean = 101.4, SD = 14.7) and for Blacks (mean = 86.9, SD = 13.0) from (Reynolds, Chastain, Kaufman, & McLean, 1987, p. 330). Significance data is from Herrnstein & Murray (1994). Note that correlation is not causation. For example poverty can be both a cause and consequence of low IQ. | |||||||
Small differences in IQ, while relatively unimportant at the level of an individual, would theoretically have large effects at a population level. Herrnstein and Murray (1994) 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.
Condition (matching IQ) Blacks Whites High school graduation (103) 91 89 College graduation (114) 68 50 High-level occupation (117) 26 10 Living in poverty (100) 14 6 Unemployed for 1 month or more (100) 15 11 Married by age 30 (100) 58 79 Unwed mother with children (100) 51 10 Has ever been on welfare (100) 30 12 Mothers in poverty receiving welfare (100) 74 56 Having a low birth-weight baby (100) 6 3 Average annual wage (100) $25,001 $25,546 from Herrnstein & Murray (1994), Chapter 14.
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 has completed college, while only 16.7% of persons with self-reported French-Canadian ancestry have done so.
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 (Sowell, pp. 7, 93), even though Affirmative action discriminates against East 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, and in some cases are the target of violence (Sowell, pp. 133-134; Purdey, 2002).
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 20-30% of all Nobel Prize winners in physics, chemistry, and medicine. 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.
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 Rushton and Jensen (2005) and Gottfredson (2005b) 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 (Gottfredson, 2005b). 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, Genetic engineering may one day be able to directly change any genetic determinants found to influence intelligence, racial traits (like skin color) or both. This change may make the genetic component of intelligence and/or racial characteristics a matter of voluntary parental (or enforced governmental) decision. In principle, such advancements would make the current concept and discussion of race and intelligence obsolete.
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| [image] | Race and intelligence |
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| Public controversy | Average test score gaps among races Culture only or partially genetic explanation? | References |
| Human race and sex group differences | ||
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| Race and intelligence | Sex and intelligence | |
| Race and crime | Sex and crime | |