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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.^[1]

This research is grounded in two controversial assumptions:

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

Much of the evidence currently cited is based on IQ testing in the United States. There is much less data from other nations, in particular the developing world, and conclusions from the US data cannot automatically be generalized to the world as a whole. While the distributions of IQ scores among different racial-ethnic groups in the US overlap and often have a comparable range, groups differ in where their members cluster along the IQ scale.^[2] Similar clustering has been reported with related variables, such as school achievement, reaction time, and brain size.^[3] Most variation in IQ in the U.S. occurs within individual families, not between races.^[4] However, even small differences in average IQ at the group level might theoretically have large effects on social outcomes.

Several hypotheses have been proposed to explain why average IQ varies among racial-ethnic groups. Certain environmental factors, such as nutrition, are thought to moderate IQ in children,^[5] 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 have engendered significant controversy. Media opinion of the role of genetic and environmental factors in explaining individual and group differences in IQ has itself been studied (1988) and found to differ from the opinion of mainstream experts.^[6] Some critics question 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. This has included accusations of bias based on assumptions about the political ideals of the researchers or the funding agencies, such as the Pioneer Fund. Some critics fear the misuse of the research, question its utility, or feel that comparing the intelligence of racial groups is itself unethical. The disparity in average IQ among racial groups does not mean that all members of one group are more intelligent than all members of another, nor that ranking group averages from "high" to "low" implies a moral ranking from "good" to "bad" or an overall ranking of "superior" to "inferior".^[7] The conclusion that racial groups in the US vary in 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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[edit] Background information

[edit] Race

Main article: 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 the United States. In an ongoing debate, some geneticists argue race is neither a meaningful concept nor a useful heuristic device,^[8] and even that genetic differences among groups are biologically meaningless,^[9] on the basis that more genetic variation exists within such races than among them,^[10] and that racial traits overlap without discrete boundaries.^[11] Concordant with this, a survey of cultural and physical anthropologists done in 1999^[12] found that the concept of race was rejected by 69% of physical anthropologists and 80% of cultural anthropologists. Other geneticists, in contrast, argue that categories of self-identified race/ethnicity or biogeographic ancestry are both valid and useful,^[13] that these categories correspond with clusters inferred from multilocus genetic data,^[14] and that this correspondence implies that genetic factors might contribute to unexplained phenotypic variation between groups.^[15]

[edit] Intelligence testing

Main article: Intelligence testing

Intelligence is most commonly measured using IQ tests. These tests are often geared to be good measures of the psychometric variable g (for general intelligence factor), 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 correlates with performance in similar life tasks (school grades and to a lower degree college grades). 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 hereditary 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 by intelligence researchers:^[16]

• 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.

[edit] 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" (<20% genetic) interpretations that posit overwhelmingly non-genetic causes (for example, socioeconomic inequality or minority group membership) that differentially affect racial groups;
2. "partly genetic" (20-80% 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.

[edit] History

Sir Francis Galton wrote on eugenics and psychometrics in the 19th C.

[edit] 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.^[17] Charles Darwin wrote in his Descent of Man (VII, On the races of Man): "[T]he various [human] 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."

Anthropologist Franz Boas was a prominent 20th C. critic of claims that intelligence differed among races.

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 opinion that there are differences in the brain sizes and brain structures of different racial and ethnic groups was widely held and studied during the 19th century and early 20th century.^[18] Average ethnic and racial group differences in IQ were first found due to the widespread use of standardized mental tests during World War I.

Foremost amongst those researching this was Stanley Porteus of the University of Melbourne, who devised his maze test as early as 1919, applying it in his study of the Aborigines in the Kimberley region and Northern Territory of Australia (1929) and later the Kalahari tribesmen of southern Africa (1934). He also used it to assess the results of pre-frontal brain surgery on mental performance, publishing his results in 1931.^[19]

Beginning in the 1930s, race difference research and hereditarianism — the belief that genetics contribute to differences in intelligence among humans — began to fall out of favor in psychology and anthropology after major internal debates.^[20] In anthropology this occurred 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."^[21] The hereditarian position was challenged by Boas' claim 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.

[edit] Post WWII and modern times

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. 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.^[22]

Charles Murray (pictured) and Richard Herrnstein started the contemporary debate with The Bell Curve in 1994.

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.^[23]

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?"^[24] In this paper, he wrote on some of the major issues that characterize the partly genetic hypothesis (20-80% genetic) 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.

In the 1980's Nobel Prize winner for his work on the development of transistors, William Shockley, postulated that the higher rate of reproduction among US African Americans was having what he termed a "dysgenic" effect (meaning an opposite of eugenics), ; especially as influenced by welfare subsidies (e.g., AFDC), which he opined, unintentionally encouraged childbearing by less productive mothers. ^[25]. He described this work as the most important work of his career, even though it severely tarnished his reputation. Shockley's published writings on this topic, were largely based on the research of Cyril Burt. Shockley also proposed that individuals with IQs below 100 be paid to undergo voluntary sterilization ^[26]. He was subsequently criticized by the media; however his involvement brought public recognition to several controversial topics. ^[27]

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.^[28] 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.^[29] 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".^[30]

[edit] Average gaps among races

Main article: Race and intelligence (Average gaps among races)

Over the years, there has been variation in both the observed average IQ of groups, as well as the relative relationships between the average IQ of groups. Early 20th century measures typically found Blacks on the low end, and Whites on the high end. Based on studies from the 1960s and 1970s, Flynn found a slightly lower average IQ of Japanese- and Chinese American children compared to White counterparts.^[31] Recent contemporary measures place Blacks on the low end, and Asians on the high end. ^[32]

[edit] Employment tests and school achievement

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.^[33] 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.^[34]

There is wide agreement that the U.S. Black-White gap among children and adolescents on achievement tests narrowed in the 1970s and 1980s, but stalled during the 1990s.^[35] On the basis of these data, Nisbett 2005 argues that the gap in g has also narrowed to "0.6-0.7 standard deviation or approximately 10 IQ points". Both Rushton and Jensen 2005b and Gottfredson 2005b argue that "gains in scholastic achievement do not equal gains in g, and the Black-White differences in g are as large as ever, even for measures of reaction time". Charles Murray argues that the U.S. Black-White gap on the SAT has increased in size to 1 SD from the 1990s to 2005.^[36]

[edit] U.S. Black-White gap

There is disagreement about whether the results of IQ tests show a narrowing of the IQ gap, or if they do who has benefited. Rushton and Jensen 2005b and Gottfredson 2005b argue that "the Black-White differences in g are as large as ever". Roth et al. 2001 found that the recent U.S. Black-White gap in g among adults is 1.1 sd, similar to characterization of the historical U.S. Black-White gap. In an analysis of standardization samples for the WAIS, WISC, SB, and AFQT, Dickens and Flynn 2006a find evidence that the U.S. Black-White gap shrunk between 3 and 6 points from 1972 to 2002. These conclusions were challenged by Rushton and Jensen 2006, and a rejoinder was made by Dickens and Flynn 2006b. Subsequently, Murray 2006 analyzed testing data from the children of the 1979 NLSY cohort, concluding that "the B-W difference did not diminish on either academic achievement or cognitive tests for children born from the mid 1970s through the mid 1990s." To reconcile the contradictory findings, Murray suggests that "the effect that Dickens and Flynn found was concentrated among subjects born before the late 1970s". In 2006, Flynn and Murray debated the shrinking Black-White IQ gap. Both agree that the gap shrunk for children born before the late 1970s, however Murray believes the narrowing stopped while Flynn believes it has continued.^[37]

Several sources have argued that the U.S. Black-White gap varies with age. Dickens and Flynn 2006b estimate that the 2006 U.S. Black-White IQ gap is 0.31 SDs at age 4, 0.63 SDs at age 12, 0.87 SDs at age 18, and 1.1 SDs at age 24. Using data from Shuey 1966, Jensen 1998 estimates that the U.S. Black-White gap is 0.70 SDs in early childhood, 1.00 SDs in middle childhood, and 1.20 SDs in early adulthood. A study of children aged eight to twelve months found a U.S. Black-White gap of 0.06 SD.^[38]

[edit] World-wide scores

One review of the global cognitive ability data is Richard Lynn's 2006 Race Differences in Intelligence, which organizes the data by nine global regions,^[40] surveying 620 published studies from around the world, with a total of 813,778 tested individuals. Lynn's meta-analysis lists East Asians (105), Europeans (99), Inuit (91), Southeast Asians and Amerindians each (87), Pacific Islanders (85), Middle Easterners (including South Asians and North Africans) (84), sub-Saharan Africans (67), and Australian Aborigines (62). Searchlight magazine criticizes Lynn's publisher, which is not an academic press and for publishing “classic” Aryan and eugenic tracts.^[41]. Lynn has previously argued at length that nutrition is the best supported environmental explanation for variation in the lower range,^[42] and a number of other environmental explanations have been advanced (see below). Ashkenazi Jews score significantly higher than other groups (107-115) in the U.S. and Britain, but estimates of the average IQ of Ashkenazim in Israel may be somewhat closer to the European mean.^[43] In other data, Hispanics average 91 and African Americans average 87,^[44] though the latter is debated.^[45] Lynn's survey is an expansion by nearly four times of the data collected in his 2002 IQ and the Wealth of Nations with Tatu Vanhanen. 'IQ and the Wealth of Nations, which dealt with the relationship between IQ and economic development, received strong criticism from some for both error and alleged bias.^[46] Lynn argues the surveyed studies have high reliability in the sense that different studies give similar results, and high validity in the sense that they correlate highly with performance in international studies of achievement in mathematics and science and with national economic development.

Related groups sometimes vary greatly in IQ in different nations. Black Africans score much lower than blacks in the US, although Black Americans average about 7-20% European admixture.^[47] Some reports indicate that the black–white gap is smaller in the UK than in the U.S.^[48] Differences between groups of whites can also be seen, ranging to the low 90s in SE Europe (with a decrease also seen in brain size).^[49] In Israel, large gaps in test scores and achievement separate Ashkenazi Jews from other groups such as the Sephardi.^[50]

[edit] Reaction time

Average racial differences have been asserted to exist on tests of response time, although it is also argued that some of these differences can be explained by cultural phenomena.^[51] Jensen has used reaction time as a proxy for IQ, despite the low correlation.^[52].

[edit] Brain size and IQ

Main article: Intelligence quotient

Many studies report that IQ has a moderate correlation with various measures of brain size.^[53] For example, a 2005 meta-analysis found that brain size correlates with IQ by a factor of approximately .40 among adults There are several hotly debated studies which have concluded that there are race differences in brain size. These studies are criticized as having not found racially-based difference, with critics arguing instead the the variation better explained in terms of geography.^[54][12]

[edit] Explanations

Main article: Race and intelligence (Explanations)

[edit] Introduction

Within individual countries, family social-economic variables are positively correlated with IQ scores. However, the black-white score gap persists at all socio-economic levels. These kinds of findings suggest that simple differences in socio-economic status cannot explain all of the IQ gap^[55].

Most intelligence researchers believe that IQ differences among individuals reflect the general intelligence factor, g.^[56] The nature of g itself is still an active area of research, and the question of whether IQ differences among groups are substantially genetic is hotly contested.

According to the American Psychological Association, the difference between the average IQ scores of Blacks and Whites in the U.S. cannot be attributed to any obvious biases in test construction or cultural biases, as opposed to more occult environmental or genetic causes.^[57] Evidence against test construction and cultural bias includes the internal consistency of item difficulty for all groups, the equivalent validity of tests in predicting academic and occupational outcomes for all groups, and the persistence of the IQ gap on relatively culture-free tests.^[58]

Although IQ differences between individuals is highly heritable, this does not mean that average IQ differences between racial groups are necessarily genetic in origin, because estimates of heritability depend on the range of environments tested^[59]. High heritability by itself is not informative about group differences, so any inferences made from within group heritability will depend on additional considerations.^[60] However, many scholars agree that no considerations of heritabilty are sufficient if group differences are caused by environmental factors that uniquely affect all members of one group but not another^[61].

[edit] Environmental explanations

Main article: IQ testing envionmental variances

Arguing that IQ tests are often wrongly described as measuring "innate" rather than developed ability, Jencks and Phillips 1998 conclude that this "labeling bias" causes people to inappropriately attribute the Black-White gap to "innate" differences.^{[62][dubious – discuss]} They assert that non-cultural environmental factors cause gaps measured by the tests, rather than any possible innate difference based on genetics, and to use these tests as a measure of innate difference is misleading and improper.^{[63][dubious – discuss]}

Estimates of the significance of genetics vs. environment are dependent on the strength of environmental factors. For example, schizophrenia, regarded as being highly heritable^{[citation needed]}, has seen increased rates in second and third generation immigrants to Western European countries which do not seem to be the result of increased genetic susceptibility, but another, as yet unidentified, environmental factor(s) that seems to have become more influential^{[citation needed]}.

Many anthropologists^[who?] 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 1st. century B.C. disparaged the intelligence of the northern Europeans of the time, as did the Moors in Iberia in the 11th century. ^[64]

In the developing world there are are 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 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.^[65]

Many studies that attempt to test for heritability find results that do not support the partly-genetic hypothesis (20-80% genetic). They include studies on IQ and skin color,^[66] self-reported European ancestry,^[67] children in post WWII Germany born to black and white American soldiers,^[68] blood groups,^[69] and mixed-race children born to either a black or a white mother.^[70] Many intervention and adoption studies also find results that do not support the genetic hypothesis.^[71] 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.^[72] Hereditarians argue that these studies are flawed due to their age, lack of replication, problems with their sample population, or that they do in fact support the partly-genetic hypothesis.^[73]

[edit] Genetic explanations

See also: Inheritance of intelligence

The contemporary debate can be traced to psychologist Arthur Jensen in 1969.

Arthur Jensen and others have concluded that the US IQ gap is partially 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. Moreover, they argue that the range of environmental factors which could account for the gap is restricted, and most previous suggestions have been empirically excluded Under their interpretation of Lakatos's technical concept of research programs, Jensen and Rushton argue that the hereditarian hypothesis (50% genetic-50% environmental) can formulate new predictions, some of which can be tested, whereas a completely culture-only hypothesis (0% genetic-100% environmental) can't, as it merely accommodates anomalies.^[74]

To support these claims, they often cite several lines of evidence that they interpret as support for a partly genetic cause of group differences in IQ:

1. Black–White–East Asian differences in IQ, reaction time, and brain size are observed worldwide in a range of cultures and environments. In the United States, significant Black-White IQ differences are observable at every age above 3 years, within every occupation or socioeconomic level tested, in every region of the country, and at every time since the invention of ability tests.^[75]
2. Jensen and other have argued that the magnitude of race differences on different IQ subtests correlate with the extent to which those subtests measures g,^[76] which also correlates with measures of the subtests heritability.^[77] From these and other findings, they argue that race differences have a partly biological basis.^[78]
3. The rising heritability of IQ with age (within all races; studies have found on average in the developed world heritability starts at 20% in infants, rises to 40% in middle childhood, and peaks at 80% in adulthood); and studies showing the virtual disappearance (~0.0) by adulthood of shared environmental effects on IQ (for example, family income, education, and home environment), with adopted siblings partaking in the studies no more similar in IQ than with strangers^[79] From these studies, they argue that most suggested environmental explanations for IQ difference between groups do not have a strong enough effect on IQ to fully account for group differences.
4. Studies of US comparisons of both parents to children and siblings to each other finding regression to differing means for different races (85 for Blacks and 100 for Whites) across the entire range of IQs,^[80] despite the fact that siblings are matched for shared environment and genetic heritage, with regression unaffected by family socioeconomic status and generation examined^[81]

Rushton and Jensen (2005a) believe that the best explanation is that 50%-80% of the group differences in average US IQ is genetic.^[82] For fuller listings of evidence for and against the partly-genetic (20-80% genetic) position, see Comparison of explanations.

Other evidence, such as transracial adoption, certain racial admixture studies, behavior genetic modeling of group differences, "life-history" traits, and evolutionary explanations have also been proposed to indicate a genetic contribution to the IQ gaps and explain how these arose.^[83]. C Critics of this view, such as Robert Sternberg, argue that these studies are either flawed and thus inconclusive, or else that they support a primarily environment (<20% genetic) hypothesis.^[84] For example, Dolan and Hamaker 2001 argue that the statistical methods linking the Black-White gap to g are insufficient.^[85]

Several recent studies have found some neuronal genes have variants that have spread to high frequencies under selective pressure and now occur in different frequencies in different global populations.^[86] Some of this selection occurred within the last 10,000 years, such as a recent variant of the ASPM gene that is found mostly among European and East Asian populations. The cause of the selective sweep and the effects of these variants are generally not yet known, although some suspect that they could be related to intelligence.^[87] Although neurogenic diversity theoretically increases the chances of functional diversity, ultimately, very little is known about the actual impact of these variants, and the researchers caution that they may not have anything to do with cognition or intelligence at all.^[88]

[edit] Expert opinion

A survey was conducted in 1987 of a broad sample of 1,020 scholars in specialties that would give them reason to be knowledgeable about IQ (but not necessarily about race). The survey was given to members of the American Education Research Association, National Council on Measurement in Education, American Psychological Association, American Sociological Association, Behavior Genetics Association, and Cognitive Science Society. According to the report, regarding the question "The source of black-white difference in IQ":

This is perhaps the central question in the IQ controversy. Respondents were asked to express their opinion of the role of genetic differences in the black-white IQ differential. Forty-five percent believe the difference to be a product of both genetic and environmental variation, compared to only 15% who feel the difference is entirely due to environmental variation. Twenty-four percent of experts do not believe there are sufficient data to support any reasonable opinion, and 14% did not respond to the question. Eight experts (1%) indicate a belief in an entirely genetic determination.^[89]

Robert Sternberg cautioned against supposing that the survey represented anything but opinion saying, "science isn't done by majority rule".^[90] 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. Carol Swain, author of The New White Nationalism reacted with some dismay to the survey, stating:

At least one important survey suggests that a belief in the biological inferiority of some races in regard to intelligence is more common than generally supposed. Smith College professor Stanley Rothman and Harvard researcher Mark Snyderman surveyed a sample of mostly scientific experts in the field of educational psychology in the late 1980s and found that 53 percent believed IQ differences between whites and African Americans were at least partly genetic in origin, while only 17 percent attributed the IQ differences to environmental factors alone (the remainder either believed the data was currently insufficient to decide the issue or refused to answer the question).

According to the American Psychological Association's 1995 task force report on intelligence research:

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.^[53]

The APA subsequently published eleven critical responses in 1997, most arguing that the report failed to examine adequately the evidence for partly-genetic (20-80% genetic) explanations.^[91] 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.^[92]

The report did agree with many of the non-race-based statements on intelligence made in The Bell Curve^[93] and concludes with a call for more reflection in debates on intelligence and for a "shared and sustained effort" in more research to answer the many unanswered questions that remain.^[94] 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.^[95]

Researchers who believe that there is no significant genetic contribution to race differences in intelligence include Flynn 1980, Brody 1992, Neisser et al. 1996, Nisbett 1998, Mackintosh 1998, Jencks and Phillips 1998, and Fish 2002. 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. Researchers who believe that there are significant genetic contributions to race differences in intelligence include McGurk 1953, Garrett 1961, Shuey 1966, Shockley 1968, Eysenck 1971, Baker 1974, Loehlin et al. 1975, Vernon 1979, Lynn 1991a, Waldman et al. 1994, Scarr 1995, Levin 1997, Jensen 1998b, Rushton 2000, and Gottfredson 2005b.

[edit] Significance of group IQ differences

See also: Practical importance of IQ

[edit] Within societies

[edit] Scope

The distribution of IQ scores among individuals of each race overlap substantially. In a random sample of equal numbers of US Blacks and Whites, Jensen (1998b) estimates most variance in IQ would be unrelated to race or social class.^[96] The average IQ difference between two randomly paired people from the U.S. population is approximately 17 points, and this only increases to 20 points when the pair are black and white. When the pair are siblings, the average difference is still 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 (20-80% 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.^[97]

Moreover, although it may appear paradoxical, it could be argued that an indirect outcome of social egalitarianism would be to raise the genetic contribution to intelligence to as high as possible, by minimizing environmental inequalities and any negatively IQ-impacting cultural and socio-economic differences.^[98] If all such inequalities could somehow be completely eliminated, 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.

[edit] Practical importance

The appearance of a large practical importance for intelligence for some life outcomes makes some scholars claim that the source and meaning of the IQ gap is a pressing social concern.^[99] Gordon 1997 and Gottfredson 1997b argue that the IQ gap is reflected by gaps in the academic, economic, and social factors correlated with IQ. However, others 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. One 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.^[100] (See "Practical importance of IQ".)

The effects of differences in mean IQ between groups (regardless if the cause is social or biological) are amplified by two statistical characteristics of IQ. 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, could theoretically have large effects for the United States population as a whole. As a demonstration of these possible effects, Herrnstein and Murray (1994) used a resampling technique to argue that, all else equal, a simulated 3-point drop in average IQ had little effect on factors like marriage, divorce, or unemployment. However, their study found that a simulated drop in IQ from 100 to 97-points increased poverty rates by 11% and the proportion of children living in poverty by 13%. In the simulation, similar rises occurred 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, when they simulated an increase in average IQ of 3-points to 103, they calculated that poverty rates fell 25%, children living in poverty fell 20%, and high school drop-out rates fell 28%.^[102]

Professors James Heckman and Nicholas Lemann, as well as several other scholars and scientists have the criticized validity and reliability of the data which led to the aforementioned findings by Herrnstein and Murray (1994).^[103][104]

[edit] Controlling for IQ

Because IQ correlates with a number of social and economic outcomes that have been found to differ between the black and white populations overall, The Bell Curve argues that the disparities in outcomes are due to group differences in IQ (See above chart).Professors James Heckman and Nicholas Lemann and others claim that its findings are based on data that is not completely valid and reliable.^[107][108]

According to Murray and Herrnsteins' Bell Curve, when IQ is statistically controlled for, 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).

White populations are not homogeneous groups 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.^[109]

For additional discussion of the effects of controlling for group differences on a variety of outcomes and groups, see Nyborg and Jensen 2001, and Kanazawa 2005.

[edit] Between nations

Richard Lynn's early research on Japanese IQ initiated an academic controversy and became part of Western countries' surprise in the early 1980s at the Japanese' unexpected economic and industrial achievements. (Discover 1982)[12]

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.^[110] Another peer-reviewed paper, Intelligence, Human Capital, and Economic Growth: An Extreme-Bounds Analysis, finds a strong connection between intelligence and economic growth.^[111] 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.^[112]

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.^[113] However, these environmental differences may operate in part by selecting for higher levels of IQ^[114]

[edit] 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; Indians in the United States and Britain; 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, Asian Indians, Japanese, and Chinese earn incomes 1.72, 1.42, 1.32, and 1.12 times the American average, respectively.^[115] 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,^[116] even though affirmative action discriminates against Asians in the admissions process (relative to Whites as well as to other minorities)^[117] 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.^[118] 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.^[119]

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.^[120] 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.^[121] In the U.S., these numbers are 2% of the population and 40% of winners. Over half of the world chess champions from 1886 to 2000 had at least one Ashkenazi Jewish parent.^[122]

Some studies have shown significant variation in IQ subtest profiles between groups. In one analysis of IQ studies on Ashkenazi Jews, for example, high verbal and mathematical scores, but average or below average visuospatial scores were found.^[123] In a separate study, East Asians demonstrated high visuospatial scores, but slightly above average, average or slightly below average verbal scores.^[124] The professions in which these populations tend to be over-represented differ, and some believe the difference is directly related to IQ subtest score patterns asserted to exist.^[125] The high visiuospatial/average to below average verbal pattern of subtest scores has also been asserted to exist in fully assimilated third-generation Asian Americans, as well as in the Inuit and Native Americans (both of Asian origin).^[126]

[edit] Public debate and policy implications

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Main articles: Race and intelligence (Public controversy), Race and intelligence (Accusations of bias), and Race and intelligence (Utility of research)

[edit] Media portrayal

Main article: Race and intelligence (Media portrayal)

Some researchers argue media coverage of intelligence-related research is often inaccurate and misleading. Snyderman and Rothman conducted a study of this phenomenon in 1988, drawing from their 1987 survey of expert opinion of intelligence-related topics. Media attention given to William Shockley in the mid 1980's often cited his Nobel Laureate status, but frequently omitted that the prize was given for physics, not medicine.^{[citation needed]}

[edit] Utility of research

One criticism of race and intelligence research, regardless of whether racial differences are genetic or not, questions its utility.

Descriptions of research into group differences in intelligence (especially genetic hypotheses) have been treated as self-evidently harmful to society by many writers, including references references to slavery, intolerance^[127], and eugenics^[128]. Even supporters of intelligence research have desccribed such research as analogous to "working with dynamite" or "dangerous play" in sports^[129], for which they have been criticized^[130]

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."^[131]

Another cricism is that it "causes major psychological harm to millions of black children and adults (with respect to self-esteem, career expectations, interracial relationships, etc.)".^[132] For example, in response to The Bell Curve Ashley Montagu, who famously stated the ideology of race is "man's most dangerous myth," wrote:

It is generally held that anyone who cries "Fire" in a crowded theatre should be held responsible for the consequences of his conduct. The same rule should apply to anyone who, motivated by racism, publishes inflammatory falsehoods concerning others, whether they be individuals, groups, or populations; they should by law be held responsible for their conduct. More than 200 years of racism, libel and slander, are enough, and so it is with use of IQ tests, which in a very real sense represent demeaning falsehoods, whether they maliciously intended or not.^[133]

Some scientists, including evolutionary biologist W. D. Hamilton, argue that suppressing race and intelligence research is actually more harmful than dealing with it honestly.^[134] Linda Gottfredson, a prominent professor whose work has been influential in U.S. workplace policy and who's also a Pioneer fund grantee 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.^[135]

[edit] Accusations of "political correctness"

It is asserted by some that misguided political correctness has led to large-scale denial of recent developments in the human sciences, including research regard group differences in cognitive ability.^[136] 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.

Gottfredson accuses others of maintaining a "double standard" for research that finds unpopular results and a "stiff professional tax on scholars whose work on race or intelligence discomfits reviewers for non-scientific reasons they need not articulate"^[137] Gottfredson further argues that high quality of work is no protection from this bias, citing the example of Arthur Jensen as both one of the most eminent^[138] and one of the most vilified psychologists^[139], hence the word Jensenism.

[edit] Accusations of racism

A racist motivation is frequently ascribed to some researchers who work on questions of race and intelligence. Both historical and contemporary researchers have been described as racists^[140], and some critics hold that it is racist to assert that there are cognitive or behavioral differences between ethnic groups. For example, psychologist Jerry Hirsch has claimed that Arthur Jensen has racist goals(Hunt 1998).

Accusations have also been aimed at the Pioneer Fund, which according to the Southern Poverty Law Center "has funded most American and British race scientists, including a large number cited in The Bell Curve"^[141] The Pioneer fund has been criticized as having a eugenic and racist political agenda ^[142], Pioneer Fund grantees include the current head J. Phillipe Rushton, along with Arthur Jensen, Linda Gottfredson, Richard Lynn, Hans Eysenck, Thomas Bouchard, David Lykken, Henry Garrett, William Shockley, Philip Vernon, and Audrey Shuey. Critics of the fund include the SPLC, IQ critic William H. Tucker, and historian Barry Mehler and his Institute for the Study of Academic Racism.

Robert A. Gordon, criticized for accepting grants from the Pioneer Fund, replied to media criticisms of grant-recipients: "Politically correct disinformation about science appears to spread like wildfire among literary intellectuals and other nonspecialists, who have few disciplinary constraints on what they say about science and about particular scientists and on what they allow themselves to believe."^[143]

[edit] Policy implications

See also: Intelligence and public policy

Public policy implications of IQ and race research are one of the greatest sources of controversy surrounding this issue.

Some proponents of a partly genetic (20-80% genetic) interpretation of the IQ gap, such as Rushton and Jensen (2005a) and Gottfredson (2005b), have sometimes argued that their interpretation does not in itself demand any particular policy response: while a conservative/libertarian commentator^[144] may feel the results justify, for example, 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.^[145] Since all races have representatives at all levels of the IQ curve, this means any policy based on low IQ affects members of all races.

According to the "Mainstream Science on Intelligence" statement published in Intelligence in 1997:

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.^[146]

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 health care, 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.^[147]

[edit] Appendix - IQ Data from various sources

NOTE: The information in the following tables is referenced to credible sources; however, it should be noted that some of these studies liberally synthesized their results from different sources and test methods. In general comparisons should only be made between similar primary sources, but this is not always possible given the wide variety of IQ tests, the fluid and debatable nature of racial categorization, and the lack of large scale representative data sets. Among the factors that invalidate comparisons across the studies are environment of the test subjects as well as inherent biases in the test procedures.

[edit] End material

[edit] See also

• Ashkenazi intelligence
• Brain to body mass ratio
• Craniometry
• Hominid intelligence
• Neuroscience and intelligence
• Height and intelligence
• Race and crime
• Sex and intelligence
• Scientific racism
• The Mismeasure of Man

[edit] Notes

[edit] References

Main article: Race and intelligence (References)

[edit] External links

[edit] 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.

[edit] Review Papers

• James Flynn and Charles Murray debate - news summary
• 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 archived version
• The Black-White Test Score Gap (1998) online (page-image) version of ISBN 0-8157-4609-1

[edit] Others

• 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
• (Skeptic Magazine): Two book reviews, by Paul R. Gross and Alondra Oubre, of Sarich’s and Miele’s book, Race: The Reality of Human Differences
• 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
• La Griffe du Lion - pseudonymously released statistical analyses on this and related subjects. (Review)
• 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.
• The Lessons of the Ashkenazim: Groups and Genes, Steven Pinker, June 2006, The New Republic.
• Are all races equally intelligent? -- Or: When is knowledge knowledge? by John J. Ray
• Black-White Gap in IQ Scores Closing, Study Finds

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