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No Dan, you are wrong as usual.
Every new major studies regarding IQ differences between black and white showed environment being the major factor.
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Almost all studies show the black/white IQ gap is environmental.
Summary
Since the publishing of The Bell Curve, a definitive study has come out of Columbia and Northwestern Universities demolishing the theory that the white/black IQ gap is largely genetically caused. But even at the time The Bell Curve was published, there was no reason to make such a claim. Of the seven major scientific studies on genes, race and IQ, six suggested that genes play no role in the IQ gap between whites and blacks, and only one suggested a genetic cause. Statistical objections can be raised to all seven early studies, but at the very least, The Bell Curve had no grounds whatsoever to imply that the IQ gap is largely genetic.
Argument
In The Bell Curve, authors Herrnstein and Murray strongly implied that the white/black IQ gap is largely genetic. (They were careful not to state that claim explicitly.) A year and a half after the book came out, scientists released the results of a well-designed, long-term study that appears to have refuted this contention. Their press release is worth quoting in full:
POVERTY ACCOUNTS FOR GAP IN IQ SCORES BETWEEN BLACKS AND WHITES (1)
EVANSTON, Ill. -- Contrary to "The Bell Curve" findings, a new study by researchers at Columbia and Northwestern Universities suggests that poverty and early learning opportunities -- not race -- account for the gap in IQ scores between blacks and whites. (The study will be published in the April [96] issue of Child Development.)
Adjustments for socioeconomic conditions almost completely eliminate differences in IQ scores between black and white children, according to the study's co-investigators. They include Jeanne Brooks-Gunn and Pamela Klebanov of Columbia's Teachers College, and Greg Duncan of the Center for Urban Affairs and Policy Research at Northwestern University.
As in many other studies, the black children in the study had IQ scores a full 15 points lower than their white counterparts. Poverty alone, the researchers found, accounted for 52 percent of that difference, cutting it to 7 points. Controlling for the children's home environment reduced the difference by another 28 percent, to a statistically insignificant 3 points -- in essence, eliminating the gap altogether.
The study includes data from birth to age 5 on 800 black and white children who were born premature and with a low birth weight. Collected from eight health care sites around the country, it is the only data set that combines high-quality measurement of developmental outcomes (i.e., full-scale IQ tests) with longitudinal data on family economic status, neighborhood conditions, family structure and home environment. Because the study looks at very young children, the subjects' IQ measures cannot be attributed to such non-family influences as schooling or work.
"The study strongly suggests that economic and learning environments of the home are the most powerful predictors of racial IQ differences in 5-year-olds," said Brooks-Gunn.
The longitudinal data allowed the researchers to measure persistent poverty -- found to be a key factor in the IQ differences. "Many children have transitory experiences with poverty," said Duncan. "For black children, poverty is likely to be much more persistent," he said. Of the black children in the study, 40 percent lived in persistent poverty, compared to 5 percent of white children.
The study also takes into account how impoverished neighborhood conditions and environmental influences can affect even children not living in poverty. Black families are more likely to live in poor neighborhoods, whether or not they are poor themselves. "Almost one half of all black children whose families were not poor resided in poor neighborhoods, compared with less than 10 percent of white children," said Duncan.
In addition, the study measured other factors associated with poverty that are more common in minority children. They include characteristics related to family structure and resources: single parents, parents with low educational levels and low literary scores, unemployed parents and young parents.
To determine the child's level of stimulation in the home environment, the data included measurements of parents' involvement and learning and language experiences that they provided for their children. For example, it measured whether the child has toys that teach color, size and shape and whether the child is encouraged to learn the alphabet and numbers.
Debate over what causes the IQ gap has been highly charged since the 1994 publication of "The Bell Curve," by Richard Hernstein and Charles Murray, who view the difference as genetic and impossible to change.
The Bell Curve hypothesis does not depend on any direct evidence, but rather on its authors' assertion that social and economic factors cannot explain it. Because the typical black ranks at the 15th percentile of the white IQ distribution, say Hernstein and Murray, black socioeconomic status (SES) can only explain the ranking if, on average, it is well below than the 15th percentile of white SES ranking.
The Bell Curve authors claim no such SES inequality exists, and this is the point the Columbia-Northwestern study calls into question. Most studies of socioeconomic status do not consider such obvious factors as family income or neighborhood conditions, and those that do fail to account for the degree of persistent poverty.
Three times as many black children as white children live in families below the official U.S. poverty line. The average black child in the United States lives in a family whose long-term income ranks at about the ninth percentile of white income distribution, according to the study. The percentile ranking for blacks drops to about the fifth percentile of white income distribution when adjusted for the very different neighborhood conditions black and white children typically live in.
The significance of these factors, and the consequent finding that the economic and learning environments of the home are the most powerful predictors of age-5 racial IQ differences, is the implication that the debate spawned by "The Bell Curve" has badly misdirected the national debate on welfare reform.
Such reform is clearly needed, said Duncan, Brooks-Gunn and Klebanov, but the point of reform should be to focus on the real problems of children rather than the presumed moral failings of their parents. Whatever the merits of requiring mandatory employment and responsible behavior, the researchers said, the key issue -- and the one with the greatest impact on the nation's future -- is how such requirements will affect family poverty.
The Bell Curve's one-sided analysis
At the time of The Bell Curve's publishing, there were seven studies in the scientific literature concerning the cause of the black/white IQ gap. Six of them point to the environment; and only one points to genetics. The authors of The Bell Curve prominently displayed only the results of the pro-genetics test in the main text. Of the others, they dismissed one in a single-paragraph side bar, dismissed another in the endnotes, and simply ignored the rest.
Psychologist Richard Nisbett has been generous enough to provide the public with the details of all seven studies: (2)
After World War II, many American GI's (both white and black) fathered children by German women; these children were then raised in German society. The children fathered by black GI's had an average IQ of 96.5, and the children fathered by white GI's had an average IQ of 97 -- a statistically insignificant difference. (3)
In another study of children raised in residential institutions, black, white and racially mixed children who were raised in the same enriched environment were given IQ tests. At four years of age, the white children had an average IQ of 103, the blacks had an average IQ of 108, and the racially mixed children had an average IQ of 106. (4)
Another study measured the IQ's of children from black-white unions. Assuming that mothers are more important than fathers in the education and socialization of their children, the study sought to see if a child's IQ is higher when the white partner is the mother. This turned out to be true -- the IQ of a racially mixed child averages 9 points higher when it is the mother who is white. (5)
A genetic study took advantage of the fact that African-Americans genes are about 20-30 percent European, and that Africans and Europeans differ just enough in their genetic blood groups to determine the degree of "Europeanness" in an individual. If intelligence were indeed genetic and favored in Europeans, we might expect blacks with greater Europeanness to be more intelligent. However, a study of 288 young blacks found almost no relationship between Europeanness and intelligence: the correlation was a trivial and nonsignificant .05. (6)
Another genetic study examined the correlation between IQ and European blood groups (as opposed to the estimated Europeanness of individuals based on blood groups). In one sample of blacks, the correlation was a trivial .01, in the other a nonsignificant -.38, with higher IQ being associated with the more African blood groups. (7)
Another study tested the hypothesis that if IQ were both hereditary and favored in Europeans, then blacks with high IQs should have several times the level of Europeanness than the black population in general. But a study of high-IQ black children in Chicago found that this wasn't the case; in fact, these black children were slightly less likely to have European ancestors. (8)
The study featured in The Bell Curve was the Scarr-Weinberg study, which examined the IQs of children from different races who were adopted by white parents. White adoptees turned out to have higher IQs than mixed-race adoptees, who had higher IQs than black adoptees. (9)
There are statistical difficulties with all the above studies. For example, Scarr and Weinberg themselves believe that their adoption study is not informative on the question of genes, race and IQ, because their study sample was small, the adoption agencies could have selectively placed the kids, the adoptive families were recruited on a voluntary basis, the natural parents' IQs were not known, the black children were adopted at a substantially later age, and the social stigma of being a black child in a white family probably has effects on development. Curiously, The Bell Curve does not report the reservations that the study authors themselves have.
Many of the same objections can be raised to the other studies. The IQs of the parents were not known, and there is a possibility that the study samples were nonrepresentative of the population being studied. Possibly, whites who breed with blacks may tend to have lower IQs. (This assertion would beg support, however, since the biracial population in the U.S. first burgeoned during the days of slavery, when wealthy slave masters and plantation owners raped hundreds of thousands of black slaves.) However, as Nisbett points out, the six studies suggesting a social rather than genetic factor were taken at very different times and places, under a wide variety of circumstances. That they should all suffer from the same sort of self-selection is therefore implausibly great.
But even accepting the statistical difficulties of all seven studies, the authors of The Bell Curve were wrong to imply that the difference in black and white IQ scores is largely genetic. At the very least, they had no hard scientific evidence at the time; at the very most, the fact that the environmental results outnumbered the genetic results six-to-one makes their suggestion completely indefensible.
Endnotes:
1. Press Release from Columbia and Northwestern Universities, April, 1996. Contact: Pat Tremmel at (847) 491-4892 or [email protected] or Barry Rosen at (212) 678-3176 or [email protected] .
2. Condensed from Richard Nisbett's article "Race, IQ and Scientism," pp. 37-42 in Steven Fraser, ed., The Bell Curve Wars (New York: HarperCollins, 1995).
3. J.R. Flynn, Race, IQ and Jensen, (London: Routledge and Kegan Paul, 1980), pp. 87-88.
4. Ibid., pp. 110-111.
5. L. Willerman, A.F. Naylor and N.C. Myrianthopoulos, "Intellectual development of children from interracial matings: performance in infancy and at 4 years," Behavior Genetics 4, 1974, pp. 84-88.
6. S. Scarr, S. Pakstis, H. Katz and W. Barker, "Absence of a relationship between degree of white ancestry and intellectual skills within a black population," Human Genetics 39, 1977, pp. 73-77, 82-83.
7. J. Loehlin, S. Vandenberg and R. Osborne, "Blood-group genes and Negro-white ability differences," Behavior Genetics 3, 1973, pp. 263-70.
8. P. Witty and M. Jenkins, "The educational achievement of a group of gifted Negro children," Journal of Educational Psychology 25, 1934, p. 586. Levels of Europeanness in subjects were based on self-reports on their ancestries.
9. S. Scarr and R. Weinberg, "The Minnesota adoption studies: Genetic differences and malleability," Child Development 54, 1983, pp. 260-267.
Every new major studies regarding IQ differences between black and white showed environment being the major factor.
-----
Almost all studies show the black/white IQ gap is environmental.
Summary
Since the publishing of The Bell Curve, a definitive study has come out of Columbia and Northwestern Universities demolishing the theory that the white/black IQ gap is largely genetically caused. But even at the time The Bell Curve was published, there was no reason to make such a claim. Of the seven major scientific studies on genes, race and IQ, six suggested that genes play no role in the IQ gap between whites and blacks, and only one suggested a genetic cause. Statistical objections can be raised to all seven early studies, but at the very least, The Bell Curve had no grounds whatsoever to imply that the IQ gap is largely genetic.
Argument
In The Bell Curve, authors Herrnstein and Murray strongly implied that the white/black IQ gap is largely genetic. (They were careful not to state that claim explicitly.) A year and a half after the book came out, scientists released the results of a well-designed, long-term study that appears to have refuted this contention. Their press release is worth quoting in full:
POVERTY ACCOUNTS FOR GAP IN IQ SCORES BETWEEN BLACKS AND WHITES (1)
EVANSTON, Ill. -- Contrary to "The Bell Curve" findings, a new study by researchers at Columbia and Northwestern Universities suggests that poverty and early learning opportunities -- not race -- account for the gap in IQ scores between blacks and whites. (The study will be published in the April [96] issue of Child Development.)
Adjustments for socioeconomic conditions almost completely eliminate differences in IQ scores between black and white children, according to the study's co-investigators. They include Jeanne Brooks-Gunn and Pamela Klebanov of Columbia's Teachers College, and Greg Duncan of the Center for Urban Affairs and Policy Research at Northwestern University.
As in many other studies, the black children in the study had IQ scores a full 15 points lower than their white counterparts. Poverty alone, the researchers found, accounted for 52 percent of that difference, cutting it to 7 points. Controlling for the children's home environment reduced the difference by another 28 percent, to a statistically insignificant 3 points -- in essence, eliminating the gap altogether.
The study includes data from birth to age 5 on 800 black and white children who were born premature and with a low birth weight. Collected from eight health care sites around the country, it is the only data set that combines high-quality measurement of developmental outcomes (i.e., full-scale IQ tests) with longitudinal data on family economic status, neighborhood conditions, family structure and home environment. Because the study looks at very young children, the subjects' IQ measures cannot be attributed to such non-family influences as schooling or work.
"The study strongly suggests that economic and learning environments of the home are the most powerful predictors of racial IQ differences in 5-year-olds," said Brooks-Gunn.
The longitudinal data allowed the researchers to measure persistent poverty -- found to be a key factor in the IQ differences. "Many children have transitory experiences with poverty," said Duncan. "For black children, poverty is likely to be much more persistent," he said. Of the black children in the study, 40 percent lived in persistent poverty, compared to 5 percent of white children.
The study also takes into account how impoverished neighborhood conditions and environmental influences can affect even children not living in poverty. Black families are more likely to live in poor neighborhoods, whether or not they are poor themselves. "Almost one half of all black children whose families were not poor resided in poor neighborhoods, compared with less than 10 percent of white children," said Duncan.
In addition, the study measured other factors associated with poverty that are more common in minority children. They include characteristics related to family structure and resources: single parents, parents with low educational levels and low literary scores, unemployed parents and young parents.
To determine the child's level of stimulation in the home environment, the data included measurements of parents' involvement and learning and language experiences that they provided for their children. For example, it measured whether the child has toys that teach color, size and shape and whether the child is encouraged to learn the alphabet and numbers.
Debate over what causes the IQ gap has been highly charged since the 1994 publication of "The Bell Curve," by Richard Hernstein and Charles Murray, who view the difference as genetic and impossible to change.
The Bell Curve hypothesis does not depend on any direct evidence, but rather on its authors' assertion that social and economic factors cannot explain it. Because the typical black ranks at the 15th percentile of the white IQ distribution, say Hernstein and Murray, black socioeconomic status (SES) can only explain the ranking if, on average, it is well below than the 15th percentile of white SES ranking.
The Bell Curve authors claim no such SES inequality exists, and this is the point the Columbia-Northwestern study calls into question. Most studies of socioeconomic status do not consider such obvious factors as family income or neighborhood conditions, and those that do fail to account for the degree of persistent poverty.
Three times as many black children as white children live in families below the official U.S. poverty line. The average black child in the United States lives in a family whose long-term income ranks at about the ninth percentile of white income distribution, according to the study. The percentile ranking for blacks drops to about the fifth percentile of white income distribution when adjusted for the very different neighborhood conditions black and white children typically live in.
The significance of these factors, and the consequent finding that the economic and learning environments of the home are the most powerful predictors of age-5 racial IQ differences, is the implication that the debate spawned by "The Bell Curve" has badly misdirected the national debate on welfare reform.
Such reform is clearly needed, said Duncan, Brooks-Gunn and Klebanov, but the point of reform should be to focus on the real problems of children rather than the presumed moral failings of their parents. Whatever the merits of requiring mandatory employment and responsible behavior, the researchers said, the key issue -- and the one with the greatest impact on the nation's future -- is how such requirements will affect family poverty.
The Bell Curve's one-sided analysis
At the time of The Bell Curve's publishing, there were seven studies in the scientific literature concerning the cause of the black/white IQ gap. Six of them point to the environment; and only one points to genetics. The authors of The Bell Curve prominently displayed only the results of the pro-genetics test in the main text. Of the others, they dismissed one in a single-paragraph side bar, dismissed another in the endnotes, and simply ignored the rest.
Psychologist Richard Nisbett has been generous enough to provide the public with the details of all seven studies: (2)
After World War II, many American GI's (both white and black) fathered children by German women; these children were then raised in German society. The children fathered by black GI's had an average IQ of 96.5, and the children fathered by white GI's had an average IQ of 97 -- a statistically insignificant difference. (3)
In another study of children raised in residential institutions, black, white and racially mixed children who were raised in the same enriched environment were given IQ tests. At four years of age, the white children had an average IQ of 103, the blacks had an average IQ of 108, and the racially mixed children had an average IQ of 106. (4)
Another study measured the IQ's of children from black-white unions. Assuming that mothers are more important than fathers in the education and socialization of their children, the study sought to see if a child's IQ is higher when the white partner is the mother. This turned out to be true -- the IQ of a racially mixed child averages 9 points higher when it is the mother who is white. (5)
A genetic study took advantage of the fact that African-Americans genes are about 20-30 percent European, and that Africans and Europeans differ just enough in their genetic blood groups to determine the degree of "Europeanness" in an individual. If intelligence were indeed genetic and favored in Europeans, we might expect blacks with greater Europeanness to be more intelligent. However, a study of 288 young blacks found almost no relationship between Europeanness and intelligence: the correlation was a trivial and nonsignificant .05. (6)
Another genetic study examined the correlation between IQ and European blood groups (as opposed to the estimated Europeanness of individuals based on blood groups). In one sample of blacks, the correlation was a trivial .01, in the other a nonsignificant -.38, with higher IQ being associated with the more African blood groups. (7)
Another study tested the hypothesis that if IQ were both hereditary and favored in Europeans, then blacks with high IQs should have several times the level of Europeanness than the black population in general. But a study of high-IQ black children in Chicago found that this wasn't the case; in fact, these black children were slightly less likely to have European ancestors. (8)
The study featured in The Bell Curve was the Scarr-Weinberg study, which examined the IQs of children from different races who were adopted by white parents. White adoptees turned out to have higher IQs than mixed-race adoptees, who had higher IQs than black adoptees. (9)
There are statistical difficulties with all the above studies. For example, Scarr and Weinberg themselves believe that their adoption study is not informative on the question of genes, race and IQ, because their study sample was small, the adoption agencies could have selectively placed the kids, the adoptive families were recruited on a voluntary basis, the natural parents' IQs were not known, the black children were adopted at a substantially later age, and the social stigma of being a black child in a white family probably has effects on development. Curiously, The Bell Curve does not report the reservations that the study authors themselves have.
Many of the same objections can be raised to the other studies. The IQs of the parents were not known, and there is a possibility that the study samples were nonrepresentative of the population being studied. Possibly, whites who breed with blacks may tend to have lower IQs. (This assertion would beg support, however, since the biracial population in the U.S. first burgeoned during the days of slavery, when wealthy slave masters and plantation owners raped hundreds of thousands of black slaves.) However, as Nisbett points out, the six studies suggesting a social rather than genetic factor were taken at very different times and places, under a wide variety of circumstances. That they should all suffer from the same sort of self-selection is therefore implausibly great.
But even accepting the statistical difficulties of all seven studies, the authors of The Bell Curve were wrong to imply that the difference in black and white IQ scores is largely genetic. At the very least, they had no hard scientific evidence at the time; at the very most, the fact that the environmental results outnumbered the genetic results six-to-one makes their suggestion completely indefensible.
Endnotes:
1. Press Release from Columbia and Northwestern Universities, April, 1996. Contact: Pat Tremmel at (847) 491-4892 or [email protected] or Barry Rosen at (212) 678-3176 or [email protected] .
2. Condensed from Richard Nisbett's article "Race, IQ and Scientism," pp. 37-42 in Steven Fraser, ed., The Bell Curve Wars (New York: HarperCollins, 1995).
3. J.R. Flynn, Race, IQ and Jensen, (London: Routledge and Kegan Paul, 1980), pp. 87-88.
4. Ibid., pp. 110-111.
5. L. Willerman, A.F. Naylor and N.C. Myrianthopoulos, "Intellectual development of children from interracial matings: performance in infancy and at 4 years," Behavior Genetics 4, 1974, pp. 84-88.
6. S. Scarr, S. Pakstis, H. Katz and W. Barker, "Absence of a relationship between degree of white ancestry and intellectual skills within a black population," Human Genetics 39, 1977, pp. 73-77, 82-83.
7. J. Loehlin, S. Vandenberg and R. Osborne, "Blood-group genes and Negro-white ability differences," Behavior Genetics 3, 1973, pp. 263-70.
8. P. Witty and M. Jenkins, "The educational achievement of a group of gifted Negro children," Journal of Educational Psychology 25, 1934, p. 586. Levels of Europeanness in subjects were based on self-reports on their ancestries.
9. S. Scarr and R. Weinberg, "The Minnesota adoption studies: Genetic differences and malleability," Child Development 54, 1983, pp. 260-267.
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