Four years ago, via VDARE.com, I was able to give the first significant publicity to IQ and the Wealth of Nations, the luminous book on IQ and the diverging economic performance of different countries co-authored by Richard Lynn with Tatu Vanhanen. Now Professor Lynn has followed up with another important book, Race Differences in Intelligence: An Evolutionary Analysis.

Its central finding: the world average IQ is no more than 90, equivalent to the mental age of a white 14-year-old. (Standardized IQ tests are normed to 100, the mental age of the average white 16-year-old.) Lynn also draws attention to the fact that a north-south IQ continuum has evolved, apparently through selection for survival in cold winters. (See the New IQ Map of the World.)

These findings in Lynn's latest book have profound geopolitical significance. They imply it may simply not be possible to transmit Western-style democratic and economic systems to the populations of Latin America and Moslem North Africa and the Middle East, let alone sub-Saharan Africa. They mean that the world's long-term problems will stem from its populations' capabilities—much deeper and more intractable than any "Clash of Civilizations"-style competition between different political concepts.

The implications for immigration are obvious: it can have fundamental, and permanent, consequences.

For Lynn, Race Differences In Intelligence represents the culmination of more than a quarter of a century's work on intelligence. It was in 1977 that he first ventured into this field—some would say minefield—with the publication of two papers on IQ in Japan and Singapore. Both showed that the East Asians obtained higher averages than White Europeans in the United States and Britain. These initial studies were disputed, but the present book lists 60 studies of the IQs of indigenous East Asians, all of which confirm the original contention. IQ and the Wealth of Nations showed that variation in IQ largely explains the problem of why some countries are rich and others poor. More recently, Lynn has helped overturn the century-long consensus that there is no average sex difference in intelligence by showing that men average 4 to 5 IQ points higher than women. (E.g. Lynn & Irwing, 2004, "Sex Differences on the Progressive Matrices: a meta-analysis," Intelligence, 32, 481-498. [pay archive] This finding is controversial even by the standards of the IQ debate—I hope to write about it soon in VDARE.COM.)

Most studies of race differences in intelligence have been local in focus. In the United States they have been largely concerned with the IQs of Whites, Blacks, Hispanics, East Asians and Native American Indians. In Australia they have been concerned with the low IQ of the Aborigines, and in New Zealand with the low IQ of the Maoris. Although a few theorists have taken a global perspective and posited genetic and evolutionary explanations for the three macro-races of East Asians, Europeans and Africans, most have typically explained the local differences by environmental and cultural factors such as poverty and racism.

Lynn's book extends the global perspective well beyond the three-macro races. He reviews more than 500 published IQ studies worldwide from the beginning of the twentieth century up to the present, devoting a chapter to each of the ten "genetic clusters," or population groups, as identified by Luigi Cavalli-Sforza and his colleagues in their mammoth 1994 book, The History and Geography of Human Genes.

Lynn regards these genetic clusters as "races." He concludes that the East Asians—Chinese, Japanese and Koreans—have the highest mean IQ at 105. Europeans follow with an IQ of 100. Some ways below these are the Inuit or Eskimos (IQ 91), South East Asians (IQ 87), Native American Indians (IQ 87), Pacific Islanders (IQ 85), South Asians and North Africans (IQ 84). Well below these come the sub-Saharan Africans (IQ 67) followed by the Australian Aborigines (IQ 62).

The lowest scoring are the Bushmen of the Kalahari Desert together with the Pygmies of the Congo rain forests (IQ 54).

After the ten chapters setting out the evidence for the average IQ of each of these ten races, there follows a chapter on the reliability and validity of the measures. These show that, although additional evidence may be required to confirm some of the racial IQ estimates, many have very high reliability in the sense that different studies give closely similar results. For instance, East Asians invariably obtain high IQs, not only in their own native homelands but also in Singapore, Malaysia, Hawaii, and North America.

To establish the validity of the racial IQs, Lynn shows that they correlate highly with performance in international studies of achievement in mathematics and science. And racial IQs also correlate with national economic development. This means they can help to explain why some countries are rich and others poor.

Lynn suggests further that IQ differences explain how quickly populations made the Neolithic transition from hunter-gatherer to settled agriculture, to building early city states, and later the development of mature civilizations.

Lynn concludes that the causes of race differences in intelligence are 50 percent genetic and 50 percent environmental. This estimate is in line with those of other recent reviews. (Arthur Jensen and I also took it as our starting point in our 2005 survey [pdf] of IQ and race difference literature published in Psychology, Public Policy, and Law.) Lynn argues that the consistency of the racial IQs in so many different places differing widely in circumstance can only be explained by powerful genetic factors.

Lynn also applies a general principle from evolutionary biology to previous analyses that found a substantial genetic contribution to the differences in intelligence between East Asians, Whites, and Blacks. He argues that wherever subspecies adapt to novel environments, they invariably develop differences in all characteristics for which there is genetic variation—such as skin colour, hair texture, musculo-skeletal traits and susceptibility and resistance to various diseases. Lynn asserts that intelligence cannot be an exception.

Lynn works out the genetic contribution in most detail for people of African descent. He argues that Blacks in the United States appear to have experienced broadly the same environment as Whites in regard to the environmental determinants of intelligence, such as nutrition, because Blacks and Whites have had the same average height since World War I. He presents evidence that Blacks in the southern states have very little White ancestry and have an average IQ of about 80, and he proposes this be adopted as the genotypic IQ of Africans. Consequently, because the average IQ for Blacks in sub-Saharan Africa is about 67, he takes this 13-point difference as the amount due to the adverse environmental conditions, principally poor nutrition, and health, found on that continent.

Lynn's last three chapters are concerned with the book's subtitle—An Evolutionary Analysis. They discuss how race differences in intelligence have evolved.

Lynn begins by putting the problem in context by summarizing Harry Jerison's (1973) classic study, The Evolution of the Brain and Intelligence. This showed that during the course of evolution, species have evolved greater intelligence in order to survive in more cognitively demanding environments. The same principle, Lynn argues, explains the evolution of race differences in human intelligence.

As early humans migrated out of Africa they encountered the cognitively demanding problem of having to survive cold winters where there were no plant foods and they had to hunt, sometimes big game. They also had to solve the problem of keeping warm. This required greater intelligence than was needed in tropical and semi-tropical equatorial Africa where plant foods are plentiful throughout the year. Lynn shows that race differences in brain size and intelligence are both closely associated with low winter temperatures in the regions they inhabit. He gives a figure of 1,282 cc for the average brain size of sub-Saharan Africans, as compared with 1,367 cc for Europeans and 1,416 cc for East Asians.

Since I have argued many of the same positions as Lynn in my book Race, Evolution, and Behavior, I will add that Lynn's brain size data are backed by a great deal of independent, converging evidence, including that from brain weights at autopsy, endocranial volume, and external head size measures. (My book provides many details of individual studies.) Moreover, magnetic resonance imaging studies make clear that the relation between brain size and intelligence is highly reliable. Lynn is on very safe ground in his statements here.

From time to time Lynn notes anomalies in his theory that require explanations. One of these is that Europeans made most of the great intellectual discoveries, while the East Asians, despite having a higher IQ, made relatively few—a paradox extensively documented by Charles Murray in his 2003 book, Human Accomplishment. Lynn proposes an explanation for this: it may be that East Asians are more conformist than Europeans and this inhibits creative achievement. (In Race, Evolution, and Behavior, I presented evidence that this personality trait has genetic roots.)

Another anomaly: the average IQ of Israel is only about 95—substantially higher than the median IQ of 85 found elsewhere in the region, but much lower than the average IQ of Jews outside of Israel, estimated at between 108 and 115.

Lynn breaks the Israeli IQ into three components: 40 percent Ashkenazim (European Jewish) with a mean IQ of 103; 40 percent Sephardim (Oriental Jewish) with a mean IQ of 91; and 20 percent Arab with a mean IQ of 86, which is virtually the same as that of Arabs elsewhere. Lynn suggests these differences could have arisen from selective migration (more intelligent Jews emigrated to Britain and the USA), intermarriage with different IQ populations (those in Europe versus those in North Africa), selective survival through persecution (European Jews were the most persecuted), and the inclusion of ethnic non-Jews among the Ashkenazim in Israel as a result of the immigration of people from the former Soviet Bloc countries who posed as Jews.

Lynn also notes some anomalies in the cold winter theory of intelligence. The most striking: the Inuit, exposed to the coldest winter temperatures, have a brain size equal to East Asians, and yet have an average IQ of only 91. To explain this anomaly, Lynn proposes that additional genetic processes are important—such as population size. The larger the network of co-operating and competing population groups ("demes"), the faster any mutations for advantageous alleles can spread. So large landmass groups like East Asians and Europeans average higher IQs than isolated hunter-gatherer groups like the Inuit.

The discussion of race and intelligence is being actively repressed on campuses as I write these words. But intellectually, the battle is over: Race realism has won. Race Differences in Intelligence is a symbol and a symptom of that victory. It may be Richard Lynn's crowning achievement.

J. Philippe Rushton [email him] is a professor of psychology at the University of Western Ontario, the author of Race, Evolution, and Behavior: A Life History Perspective. This article is adapted from Personality and Individual Differences, March 2006 (PDF)]