Comment by:
By #J. P. Rushton "Prof"32;# (University of Western Ontario) - See all my reviews 32;
The book's central finding: the world average IQ is no more than 90, and declines from north to south. An IQ of 90 is equivalent to the mental age of a White14-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.
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.
Lynn's book 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's last three chapters are concerned with the book's subtitle-An Evolutionary Analysis. They discuss how race differences in intelligence have evolved.
Lynn argues that 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, 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.