Race and intelligence

There is no scientific consensus as to the relationship between race and intelligence. Indeed, there is no scientific consensus to support the notion of race as a valid or useful biological construct, and although the notion of intelligence has more acceptance, it too is fraught with difficulties of definition and usage, and is seriously challenged as a scientific construct.

Leaving the unresolved question of "just what do we mean by intelligence?" aside, and defining it - unsatisfactorally - for the time being simply as "mental ability", there is no room to doubt that an individual's intelligence is significantly influenced by genetic factors. (See nature versus nurture for more on this.)

Its important to remember that human beings are proven to be virtually indistinct from each other. Mitochondrial dna evidence, carrying markers in the male Y chromosome, have shown all people to be related to a small African population of only 5 to 10 thousand, around 75 thousand years ago. What this means, is that there is so little in terms of differences between "races" that as to make the concept of race, itself, scientifically invalid. Many still fail to understand this basic fact, and thus, obsolete, "old science" concepts of race still hold virtue in current discourse.

Within nature versus nurture research, however, science sometimes shows anomalies, which some misinterpret to mean a causal relationship between genes and later qualitative quantities of human development.

The existing evidence on the relationship between intelligence and heredity, and intelligence and racial groups (which is not necessarilly the same topic) can be interpreted both ways. In the past most race-based claims about intelligence were incorrect and unscientific; many of the earlier claims were inspired not by science but rather by racism. For this reason the topic remains very controversial, and for some, taboo.

In early US IQ testing, Americans of African descent people were assigned significantly lower average scores (mean of 85) than "white" people (mean of 100), with "Hispanics" somewhere in between. These studies were later rejected as badly flawed for a number of reasons, notably because they did not control for the relationship between IQ and education level or income. Since higher intelligence certainly is a product of better education and higher income - and indeed it is in part defined as the ability to have an educatiopn and earn income - the lack of a correction for these factors made the earlier studies scientifically useless. However, some later studies in the same tradition have attempted to make corrections for the lack of control; certain of these make the measured IQ gap only slightly smaller; provided one ignores the vast conceptual problems posed by IQ testing and simply examines the detailed methodological isues, these studies suggest that a significant gap does exist, but, curiously, find no significant IQ gap between "white", "Jewish" and "Asian" people.

These studies have received an extremely skeptical reception in the scientific community, partly because of methodological problems in studies in the early 20th century which purported to show large IQ deficits in Irish and southern European immigrants to the United States.

Much of the controversial research has been summarized, in great detail, in The Bell Curve, published in 1994 by Richard J. Herrnstein and Charles Murray. It immediately attracted much media attention, and was denounced by some as thinly veiled racism. The authors were once publicly denounced as Nazis.

In response to the debate, a public statement circulated by 52 internationally known scholars was published in The Wall Street Journal, 12/3/94, which summarized what they considered to be the mainstream views on race and IQ.

Since then, many scientists have disputed the evidence presented in The Bell Curve, and have found what they see as serious methodological flaws. A critique of the book can be found in the revised and expanded edition of The Mismeasure of Man, by Stephen Jay Gould (1996, W. W. Norton and Co., ISBN: 0393039722.)

The book The Bell Curve Debate : History, Documents, Opinions, edited by Russell Jacoby and Naomi Glauberman, offers a range of responses to the book and these issues.

Anthropologists have argued that intelligence is a cultural category; some cultures emphasize speed and competition more than others, for example. Tests based on word skills cannot accurately measure learning ability. And most IQ tests ask people to solve problems most often encountered in middle class settings. Low IQ scores are often the result of the subject speaking a different language or dialect than the test questions, or being given the test by someone from another ethnic group, or simply being tired, malnourished, or ill. IQ tests do not measure mental ability, they do measure enculturation. During WWI African-Americans from the north tested higher than those from the south. This is simply because African-Americans in the north had received more formal education (see Race: Science and Politics, written by Ruth Benedict in 1940). Thousands of ethnographic studies indicate that innate capacities for cultural evolution are equal among all human populations. See the American Anthropological Association's Statement on Race and Intelligence [[1]]

Assuming that this gap in IQ (and SAT scores) is real, even when corrected for social and financial differences, it is not clear what the origins of this gap are. Part of this gap may well be genetic; there is no a priori reason to believe that every ethnic group or race has precisely the same genes in all areas of neural development; a small amount of random variation early on may have later crystallized into such differences at later times. Also there might have been smaller evolutionary pressure towards greater intelligence in some environments. However, the possibility that any differences are genetic do not explain why minorities in some societies show similar deficits in IQ even where they are genetically identical to the majority population (such as Catholics in Northern Ireland, or Burakumin in Japan).

Scientists have firmly established that most genetic variations in individuals are only a part of the picture of how an individual develops. The environment that a person is brought up in is equally important. Further, there are painful social factors involved, such as the high rate of drinking, smoking, and illicit drug use during pregnancy of inner-city teenagers. These activities are known to cause measurable mental damage to children born to parents engaging in such activities. Thus, as cities and states work to reduce the amount of smoking, alcoholism and illicit drug use, this may significantly reduce much or all of the IQ and SAT score gaps that are currently being measured. In this case, the gap would be a symptom of a wider social problem, and not a statement about race at all.

In recent years there have been a few theories as to why Ashkenazi Jews seem to have higher intelligence and success than people in many other ethnic groups. One theory by Gregory Cochran, based on studies of genetic disease of the brain peculiar to Ashkenazi Jews, proposes that recessive forms of certain mutations have an adaptive function that results in higher intelligence. A discussion and critique of this theory is presented on the following page:

Overclocking: A theory on genetic disease, intelligence and Ashkenazi Jews

A recent paper in the Psychological Review, "Heritability Estimates Versus Large Environmental Effects: The IQ Paradox Resolved" by William T. Dickens of The Brookings Institution and James R. Flynn presents a mechanism by which environmental effects on IQ may be magnified by feedback effects. This may provide a resolution of the contradiction between the viewpoint of The Bell Curve's authors and the repeatedly observed 'nurture' effects observed by others.