IQ And Global Inequality: “The Most Important Contribution To Economic Understanding Since Adam Smith.”

by J. Philippe Rushton:
Winters Are Good For Your Genes]

IQ and Global Inequality,
 the new book by

Richard Lynn
and Tatu Vanhanen, is an elaboration
and extension of their IQ and the Wealth of Nations,
which was reviewed on VDARE.COM

by myself
and by

Steve Sailer.
In that book the authors presented
measured IQs for 81 countries and estimated IQs for the
remaining countries in the world—a total of 185. They
showed that these IQs correlated around 0.70 with per
capita income and rates of economic development. This
was predictable,

they argued
, because

intelligence is correlated with earnings among
Nations are aggregates of individuals,
so the same correlation could

plausibly be expected across nations.

This was a very
bold claim. The cause of national differences in wealth
is one of the major problems in economics. Hundreds of
books have been written on the subject and several
journals are devoted to it. The problem has also been
addressed by sociologists, historians, psychologists and
most recently by an evolutionary biologist,

Jared Diamond
. None of these have suggested that
national differences in intelligence might be a major
factor determining why some nations are so rich while
others are so poor.

Perhaps they
lacked the courage.

In my view, Lynn
and Vanhanen have made what is arguably the most
important contribution to economic understanding since

Adam Smith
showed that

free markets promote economic development
. They have
shown also that national IQs explain much of the
variation between nations in a wide range of


phenomena—not just income levels. 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

In advancing
their intelligence theory, Lynn and Vanhanen begin by
noting that economists usually regard it as axiomatic

all peoples of the world
have the same intelligence.
For instance, Richard Easterlin, then Kenan Professor of
Economics at the University of Pennsylvania, wrote in

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.”
Isn`t the Whole World Developed?

Journal of Economic
Vol. 41, No. 1]

As another, more
recent example, we meet the same claim in December 2000
by Eric Hanushek and Dennis Kimko in The American
Economic Review

“We assume that the international
level of average ability of students does not vary
across countries” [
Labor-Force Quality, and the Growth of Nations


This assumption
that the
average level of
intelligence is the
same in all nations is seriously wrong. Lynn and
Vanhanen have

national differences in average intelligence
. Some
countries in sub-Saharan Africa

appear to have average IQs of 67
. Some of the

“Asian Tiger”
nations of the

Pacific Rim
average out at 105. This is very

For perspective,
the reader might note that an IQ of 70 is the lower
limit for

primary school educability
, and an IQ of 105 the
lower limit for College-level (although of course these
can always be

“dumbed down”).

Lynn and
Vanhanen`s work got a mixed reception. Some were

; others were

vehemently hostile.
 Many preferred to ignore the

In IQ and
Global Inequality,
Lynn and Vanhanen build on their
previous work and extend it in six directions.

  • First, they
    have increased the number of countries for which
    they have calculated measured IQs from 81 to 113.
    They show that, in the new larger sample of 113
    countries, 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
    countries for which they were unable to provide
    measured IQs, i.e. from neighbouring countries 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 97 in

    . By the use of this method, they provide
    IQs for

    all 192 countries 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 the estimates of national IQs from the
    measured IQs of

    neighbouring countries
    . They show that there is
    a correlation of 0.91 between the estimated IQs for
    32 countries given in their first book and the
    measured IQs for the same countries given in
    their new book. This establishes their case that the
    estimated IQs were remarkably accurate.


  • Fourth, a
    number of critics attacked the reliability and
    validity of the national IQs. To address this
    question the new book presents results of 71
    countries for which two independent measures of IQ
    have been obtained and show that the correlation
    between these is 0.95, which is a very high
    reliability. To establish the validity of national
    IQs they present the results of national scores from
    tests of


    . These correlate with national IQs from
    0.79 to 0.89, which is a very high validity.


  • Fifth,
    IQ and Global Inequality
    examines the relation
    between national IQs and a variety of social
    phenomena. A path model in which genes and
    environment both contribute equally (0.50) to
    national IQs allows a determination of economic
    growth (0.71) from 1500 to 2000. These national
    differences in the rate of economic growth are
    almost entirely responsible for the contemporary
    differences in per capita income (0.98). The model
    also posits that national IQs are determinants of a
    number of social phenomena such as

    adult literacy
    (0.64), enrolment in tertiary
    education (0.75), life expectancy (0.77), and


    Of course, some of these phenomena have
    positive feedback relationships. For instance,
    countries whose populations have high IQs have high
    per capita incomes, which 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


As often happens
with important discoveries in science, the fact that
these national differences in intelligence must
inevitably determine

differences in economic development
seems obvious in

Indeed, it seems
astonishing that no-one had hitherto advanced this
simple thesis—even before the recent

Dark Age

Political Correctness
closed in.

J. Philippe Rushton

is a professor of
psychology at the University of Western Ontario, the
author of
 Race, Evolution, and Behavior: A Life History Perspective.