thegenepoolofthehumansspeciescannotbechangingasrapidlyasIQscores
are rising. Indeed, there is no evidence that people who score higher on IQ tests
are reproducing at greater rates. If anything, the evidence suggests that people
who score high on intelligence tests have lower fertility rates, at least within the
last century (Van Court & Bean, 1985).
In general, then, the research is consistent with the notion that environmental
factors can have a large effect on the development of intellectual competency,
even as measured by conventional IQ tests. The fact that people inherit genes
that somehow influence intelligence, however measured, does not mean that
intelligence is immutable.
Ethnic Differences in IQ Performance
Another unfortunate implication sometimes drawn from the hereditarian theory
of intelligence is based on the finding that people from minority groups, such
as Native Americans and African Americans, tend to score lower on IQ tests
than people from majority groups such as European Americans (Herrnstein &
Murray, 1994; Neisser et al., 1996). Yet IQ tests predict academic performance
among minority people, suggesting that the tests are not unreasonable mea-
sures of intelligence in minority populations (Scarr-Salapatek, 1971; Oakland,
1983). The unfortunate implication sometimes drawn from these findings is that
European people possess a genetically determined intellectual potential that
exceeds that possessed by peoples from other parts of the world (Jensen, 1969).
Some hereditarians claim that Asian people possess the most favorable genes
for intellectual potential (Rushton, 1988, 1991). Such claims have historically
been used to justify racial segregation and racist social and economic policies.
They have also been used to discourage the spending of economic resources on
the education of people from minority cultures.
Again, the implication that ethnic differences in performance on IQ tests
are genetic need not be drawn from a hereditarian theory of intelligence. It is
perfectly consistent with the hereditarian view that individual differences in
intelligence are primarily due to genes but ethnic differences in measured in-
telligence are primarily due to environmental factors. I think that the consensus
position is that ethnic differences in IQ performance reflect differences in cul-
tural environments. Specifically, the cultural environment of the typical Euro-
pean (and in some cases, Asian) is more conducive to learning the skills that
enable a person to do well on IQ tests than is the cultural environment of the
typical African American or Hispanic American or Native American.
Evidence against a Genetic Basis for Ethnic IQ Differences Several lines of evidence
support the claim that ethnic differences in IQ performance are a consequence
of environmental and cultural factors and not a matter of genetic differences.
First of all, when children from a minority group that typically scores lower
on IQ tests are raised in the same environment as children from the majority
culture, the IQ scores of those minority children are similar to the IQ scores of
the majority children. Scarr and Weinberg (1976, 1983) examined the IQ scores
of African-American children born of mostly lower income parents but adopted
by European-American families from mostly the middle and upper middle
economic brackets. The IQ scores of the adopted African Americans averaged
Individual Differences in Cognition 799