The Bell Curve: Intelligence and Class Structure in American Life (49 page)

As the table indicates, black progress in narrowing the test score discrepancy with whites has been substantial on all three tests and across all of the age groups. The overall average gap of .92 standard deviation in the 1969-1973 tests had shrunk to .64 standard deviation by 1990. The gap narrowed because black scores rose, not because white scores fell. Altogether, the NAEP provides an encouraging picture.

The first published breakdowns of SAT scores by ethnicity appear for 1976, when the downward trend in SAT scores nationwide after 1963 was nearing its bottom (see Chapter 18). From 1976 to 1993, the white-black gap in SAT scores narrowed from 1.16 to .88 standard deviation in the verbal portion of the test and from 1.27 to .92 standard deviation in the mathematics portion of the test.
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Comparable narrowing has also brought black and white achievement test scores closer, as presented in Appendix 5. Because the ethnic self-identification of SAT test takers contains some anomalies
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and because the SAT pool is unrepresentative of the general population, the numbers should be interpreted with caution. But even so, the SAT data indicate a narrowing gap. Black SAT test takers improved substantially more in scores than white SAT test takers, and neither the changes in the pool of test takers nor the well-advertised national decline in SAT scores was responsible, for reasons explained in the notes.
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E
XPLAINING THE
C
ONVERGENCE.
Let us assume that during the past two decades black and white cognitive ability as measured by IQ has in fact converged by an amount that is consistent with the convergence in educational aptitude measures such as the SAT or NAEP—a narrowing of approximately .15 to .25 standard deviation units, or the equivalent of two to three IQ points overall.
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Why have the scores converged? The answer calls for speculation.

We take for granted that individual variations in cognitive ability depend on both genes and environment (see Chapter 4). In a period as short as twenty years, environmental changes are likely to provide the main reason for the narrowing racial gap in scores.
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Real and important though the problems of the underclass are, and acknowledging that the underclass is disproportionately black, living conditions have improved for most African-Americans since the 1950s—socially, economically, and educationally.

Consider the schools that blacks attend, for example. Some schools in the inner cities are worse than they were thirty years ago, but proportionately few blacks live in these worst-of-the-worst areas.
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Throughout the South and in much of the rest of the country, many black children as recently as the 1950s attended ramshackle schools with undertrained teachers and meager teaching materials. Any comparison between the schools that most blacks attend now and the ones they attended in the 1950s favors contemporary schools. Assuming that
education affects cognitive capacity, the rising investment in education disproportionately benefits the cognitive levels at the lower end of the socioeconomic spectrum.

The argument can be repeated for public health. If nutrition, shelter, and health care affect intellectual development, then rising standards of living are disproportionately going to show up in rising scores for the economically disadvantaged rather than for the upper classes. For travel and its educational benefits, the argument also applies. Not so long ago, many less advantaged people spent their lives within a few miles of their birthplaces. Today, Americans of nearly all walks of life crowd the interstate roads and the airports. Finally, for that most contemporary form of vicarious travel—the popular media—the leveling is still more dramatic. The modern media can bring the world to everyone in ways that were once open only to the rich.

Because blacks are shifted toward the lower end of the socioeconomic range, such improvements benefit them, on average, more than whites. If the improvements affect cognitive development, the black-white gap should have contracted. Beyond this socioeconomic leveling, there might also have been a leveling due to diminishing racism. The legacy of historic racism may still be taking its toll on cognitive development, but we must allow the possibility that it has lessened, at least for new generations. This too might account for some narrowing of the blackwhite gap.

L
OOKING TO THE
F
UTURE.
The question that remains is whether black and white test scores will continue to converge. If all that separates blacks from whites are environmental differences and if fertility patterns for different socioeconomic groups are comparable, there is no reason why they shouldn’t. The process would be very slow, however. If it continues at the pace observed over the last twenty years, then we could expect black and white SAT scores to reach equality sometime in the middle of the twenty-first century, but linear extrapolations over such long periods are not worth much.
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If black fertility is loaded more heavily than white fertility toward low-IQ segments of the population, then at some point convergence may be expected to stop, and the gap could even begin to widen again. We take up the fertility issue in Chapter 15. A brief summary statement concerning fertility patterns is that the news is not good. For now, the test score data leave open the possibility that convergence has already
stalled. For most of the tests we mentioned, black scores stopped rising in the mid-1980s. On the NAEP, the B/W gap actually increased from 1986 to 1990 in all but one test group (the math test for 17-year-olds). On the SAT, black scores on both verbal and math parts were nearly flat for the five years ending in 1993, after substantial gains in the preceding decade. On the ACT, however, black scores continued to rise after 1986, albeit modestly.
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One explanation for the stalled convergence on the NAEP and SAT is that American education stopped improving for everyone, blacks included. This is consistent with the white experience on the SAT, where white scores have also been nearly flat since the mid-1980s. But the logic is suspect. Just because a group at a higher mean stops improving does not imply that a group with a lower mean should also stop improving. On the contrary, pessimists can develop a case that the convergence of black and white SAT scores in the last two decades is symptomatic of what happens when education slows down toward the speed of the slowest ship in the convoy. It may well be that education improves for students at the low end of the distribution but gets worse (or, more optimistically, improves less) for students at the top end.
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If that is the case, the gap between people at the low and high end of the distribution should narrow, but the narrowing will stop once the educational system completes its readjustment favoring less capable students.

The narrowing black-white gap on the SAT looks consistent with some such explanation.
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Seen from one perspective, there is good news all along the spectrum of test scores. From 1980 to 1993, the proportion of black test takers who scored in the 700s on the SAT-Verbal increased by 27 percent, for example.
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But such changes at the high end of the range of test scores mean little, because so small a proportion of all black students were involved.
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The real source of the black increase of twenty-three points in the average verbal test score from 1980 to 1993 was a rise in the scores at the low end of the range. More than half (51 percent) of the gain occurred because the proportion of black students scoring in the 200s dropped from 42 percent to 30 percent.
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In contrast, less than 1 percent (0.4 percent) of the gain occurred because of the change in the proportion of black students scoring in the 700s. For the math test, 22 percent of the gain from 1980 to 1993 was accounted for by a drop in students scoring in the 200s; 4 percent of it was accounted for by an increase in students scoring in the 700s.

Pessimists reading these data may think of an analogy with the increases
in height that follow from better nutrition: Better nutrition helps raise the height of children whose diets would otherwise have been inadequate, but it does not add anything to the height of those who have been receiving a good diet already.
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Optimists may use the opposite sort of nutritional analogy: the experience of trying to lose weight. Even a successful diet has its plateaus, when the weight stubbornly stops coming off for a while. A plateau is all that we are seeing in recent test data. Perhaps convergence will resume or even accelerate in the near future.

At the least, the optimists may say that it is too soon to pass judgment, and that seems the safest conclusion. As we reach the end of this discussion of convergence, we can imagine the responses of readers of varying persuasions. Many of you will be wondering why we have felt it necessary to qualify the good news. A smaller number of readers who specialize in mental testing may be wondering why we have given so much prominence to educational achievement trends and a scattering of IQ results that may be psychometrically ephemeral. The answer for everyone is that predicting the future on this issue is little more than guesswork at this point. We urge upon our readers a similar suspension of judgment.

This brings us to the flashpoint of intelligence as a public topic: the question of genetic differences between the races. Expert opinion, when it is expressed at all, diverges widely. In the 1980s, Mark Snyderman and Stanley Rothman, a psychologist and a political scientist, respectively, sent a questionnaire to a broad sample of 1,020 scholars, mostly academicians, whose specialties give them reason to be knowledgeable about IQ.
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Among the other questions, they asked, “Which of the following best characterizes your
opinion
of the heritability of the black-white difference in IQ?” (emphasis in the questionnaire item). The answers were divided as follows:

The difference is entirely due to environmental variation: 15 percent.

The difference is entirely due to genetic variation: 1 percent.

The difference is a product of both genetic and environmental variation: 45 percent.

The data are insufficient to support any reasonable opinion: 24 percent.

No response: 14 percent.

The responses reveal the degree of uncertainty within the scientific community about where the truth lies. We have considered leaving the genetics issue at that, on grounds that no useful purpose is served by talking about a subject that is so inflammatory, so painful, and so far from resolution. We could have cited any number of expert reassurances that genetic differences among ethnic groups are not worth worrying about. For example, a recently published textbook from which college students around the country are learning about intelligence states unequivocally that “there is no convincing direct or indirect evidence in favor of a genetic hypothesis of racial differences in IQ.”
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Stephen J. Gould, whose
Mismeasure of Man
so successfully cemented the received wisdom about IQ in the media, expresses this view as confidently and more eloquently. “Equality [of the races] is not given a priori,” he once wrote in his column for
Natural History
magazine. “It is neither an ethical principle (though equal treatment may be) nor a statement about norms of social action. It just worked out that way. A hundred different and plausible scenarios for human history would have yielded other results (and moral dilemmas) of enormous magnitude. They just didn’t happen.”
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He goes on to make three arguments. First, the very concept of race is illegitimate, given the extensiveness of interbreeding and the imprecise nature of most of the traits that people think of as being “racial.” Second, the division of races is recent, occurring only in the last tens or perhaps hundreds of thousands of years, limiting the amount of time that groups of humans could have taken separate evolutionary paths. Third, developments in genetics demonstrate that the genetic differences among human beings are minor. “We now know that our usual metaphor of superficiality—skin deep—is literally accurate,” Gould writes.
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He concludes: “Say it five times before breakfast tomorrow; more important, understand it as the center of a network of implication: ‘Human equality [i.e., equality among the races] is a contingent fact of history.’”
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Our difficulty with this position is not that Gould (or others who make similar arguments) is wrong about the blurred lines between the races, or about how long the races have been separated, or about the number of genes that are racially distinctive. All his facts can be true, and yet people who call themselves Japanese or Xhosa or Caucasians or
Maori can still differ intellectually for genetic reasons. We may call them “ethnic groups” instead of races if we wish—we too are more comfortable with
ethnic,
because of the blurred lines—but some ethnic groups nonetheless differ genetically for sure, otherwise they would not have differing skin colors or hair textures or muscle mass. They also differ intellectually on the average. The question remaining is whether the intellectual differences overlap the genetic differences to any extent.

Our reason for confronting the issue of genetic cognitive differences is not to quarrel with those who deny them. If the question of genetic differences in cognitive ability were something that only professors argued about among themselves, we would happily ignore it here. We cannot do so, first because in the public discussion of genes and intelligence, no burden of proof at all is placed on the innumerable public commentators who claim that racial differences in intelligence are purely environmental. This sometimes leads to a next statement: that the differences are therefore inauthentic and that public policy must be measured against the assumption that there are no genuine cognitive differences between the races.
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The assumption of genetic cognitive equality among the races has practical consequences that require us to confront the assumption directly.