Richard Lynn and Tatu Vanhanen IQ and Global Inequality.
(2006).
Atlanta, Georgia: Washington Summit Publishers (PO Box 3514, Augusta,
GA 30914)
PB ISBN: 1-59368-024-4; HB ISBN: 1-59368-025-2.
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Reviewed by J.Philippe Rushton in Personality and Individual Differences,
2006, 41, 983-5
This new book by Richard Lynn and Tatu Vanhanen is an elaboration of
their IQ and the Wealth of Nations (2002). In their previous
book they presented measured IQs for 81 nations and estimated IQs for
all the remaining nations in the world. They showed that these IQs are
highly correlated with per capita income and rates of economic development.
They argued that this could be predicted, since intelligence is correlated
with earnings among individuals. Nations are aggregates of individuals
so the same correlation would be expected across nations. They claimed
to have shown that this is indeed the case and that the correlations
between per capita income and rates of economic development are around
0.7.
This was a very bold claim. The causes of national differences
in wealth are one of the major problems in economics on which
hundreds of books have been written and to which several journals are
devoted. The problem has also been addressed by sociologists (Max Weber),
historians (David Landes), psychologists (David McClelland) and physiologists
(Jared Diamond). None of these have suggested – dared to suggest? – that
national differences in intelligence might be a major factor determining
why some nations are so rich while others are so poor .
In advancing their intelligence theory, Lynn and Vanhanen begin
by noting that economists regard it as axiomatic that all peoples of the world
have the same intelligence. For instance, Richard Easterlin, the Kenan Professor
of Economics at University of Pennsylvania, has written that "I
think we can safely dismiss the view that the failure of modern technological
knowledge to spread rapidly was due to significant differences among nations
in the native intelligence of their populations. To
my knowledge there are no studies that definitively establish differences,
say, in basic IQ among the peoples of the world." (1981, p.5).
More recently, two other economists, Eric Hanushek of the Hoover Institution
and Dennis Kimbo of the American National Bureau of Economic Research reiterated
this position: "we assume that the international level of average ability
of students does not vary across countries" (Hanushek and Dennis Kimbo,
2000, p. 1191).
Lynn and Vanhanen have examined the assumption
of economists that the average level of intelligence is the same in
all nations and shown that it is seriously wrong. To the contrary, there are
huge national differences in intelligence that range between an average of
67 in sub-Saharan Africa to 105 in the “Asian tiger” economies
of the Pacific Rim. Like many important discoveries in science, it seems obvious
in retrospect that these national differences in intelligence must inevitably
determine differences in economic development. Indeed, it seems astonishing
that no-one had hitherto advanced this simple thesis. Nevertheless, it was
only to be expected that their work would get a mixed reception and that while
some would be convinced others would be vehemently hostile. Thus, for Edward
Miller, professor of economics at the University of New Orleans, “the
theory helps significantly to explain why some countries are rich and some
poor” (2002, p.522). But for Astrid Ervik of the University of Cambridge, "the
authors fail to present convincing evidence and appear to jump to conclusions" (2003,
p.406).
Lynn and Vanhanen’s new book builds
on their previous work and extends it in six directions. First, they have increased
the number of nations for which they have calculated measured IQs from 81 to
113. They show that in the new larger sample of 113 nations the correlation
between IQ and per capita income for 2002 is 0.68, virtually identical to the
correlation reported in their earlier book.
Second, they use the same method for estimating the IQs of nations for
which they were unable to provide measured IQs, i.e. from neighbouring nations
with culturally and racially similar populations (e.g. the IQ of Latvia is
estimated at 98 from the measured IQs of 99 in Estonia and 97in Russia). By
the use of this method they provide IQs for all 192 nations in the world. For
these the correlation between IQ and per capita income for 2002 is 0.60.
Third, they address the argument made by several critics of the
invalidity of their estimates of national IQs from the measured IQs of neighbouring
nations. They show that there is a correlation of .91 between their estimated
IQs for 32 nations given in their first book and the measured IQs given in
their new book. This establishes their case that their estimated IQs were remarkably
accurate.
Fourth, a number of critics attacked the reliability and validity
of their national IQs. For Barnett and Williams (2004), their national IQs
are “virtually meaningless”. To address the issue of the reliability
of national IQs they present results of 71 nations for which two independent
measures of IQ have been obtained and show that the correlation between these
is 0.95. This shows that their IQs have very high reliability. To establish
the validity of national IQs they present the results of a number of studies
of national scores of school students in tests of mathematics and science.
They show that the correlations of these with national IQs range between 0.79
and 0.89. This establishes that their IQs have very high validity as measures
of national differences in cognitive ability.
Fifth, the present book breaks new ground by examining the relation
between national IQs and a variety of social phenomena. They present a path
model in which genes and environment contribute equally to national IQs, which
are determinants of economic growth from 1500 to 2000 (.71). National differences
in historical rates of economic growth are almost entirely responsible for
contemporary differences in per capita income (0.98). The model also posits
that national IQs are determinants of a number of social phenomena including
adult literacy (0.64), enrolment in tertiary education (0.75), life expectancy
(0.77), and democratisation (0.57).
They propose that some of these phenomena have reciprocal causal
or positive feedback relationships. For instance, nations whose populations
have high IQs have high per capita incomes, and these enable them to provide
high quality nutrition, education and health care for their children, and these
enhance their children’s intelligence. This is the principle of genotype-environment
correlation applied to national populations.
Six, Lynn and Vanhanen address the question of the causes of national
differences in intelligence. They conclude that this lies in the racial composition
of the populations. They were led to this conclusion from the observation that
national IQs are predictable from the racial composition of the populations.
Thus, the six East Asian nations (China, Japan, South Korea, Taiwan, Hong Kong
and Singapore) all have IQs in the range between 105 and 108. The 29 European
nations all have IQs in the range between 92 and 102, while the 19 nations
of sub-Saharan Africa all have IQs in the range between 59 and 73. They show
that there is remarkable consistency in the IQs of nations when these are classified
into racial clusters.
In their new book Lynn and Vanhanen have convincingly refuted those
critics who asserted that their national IQs lack reliability and validity.
For economics, they have made what is arguably the most important contribution
to economic understanding since Adam Smith showed that free markets promote
economic development. They have also shown that national IQs explain much of
the variation between nations in a wide range of economic and social phenomena.
Their book extends the explanatory power of the concept of intelligence in
a way that makes a major contribution to the integration of psychology with
the other social sciences.
References
Barnett, S.M. and Williams, W. (2004). IQ and the Wealth of Nations: Review.
Contemporary Psychology, 49, 389-396.
Easterlin, R. A. (1981). Why isn't the whole world developed? Journal
of
Economic History, 41, 1-18.
Ervik, A.O. (2003). Review of IQ and the Wealth of Nations. The
Economic
Journal, 113, F406-408.
Hanushek, E.A. and Kimko, D.D. (2000). Schooling, labor force quality,
and the growth of nations. American Economic Review, 90, 1184-1208.
Lynn, R. and Vanhanen, T. (2002). IQ and the Wealth of Nations.
Westport, CT: Praeger.
Miller, E. M. (2002). Differential intelligence and national income. Journal
of Social,
Political and Economic Studies, 27, 513-522.
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