Race Differences in Intelligence (book) - Overview

Overview

As with Lynn's and Tatu Vanhanen's 2006 book IQ and Global Inequality, the book was published by Washington Summit Publishers. It was followed in 2008 by The Global Bell Curve. Lynn's survey is an expansion by nearly four times of the data collected in his 2002 book IQ and the Wealth of Nations with Tatu Vanhanen, which dealt with the relationship between IQ and economic development.

The book claims to represent the largest collection and review of the global Intelligence Quotient (IQ) data, surveying 620 published studies from around the world, with a total of 813,778 tested individuals. Lynn's meta-analysis lists East Asians (IQ 105), Europeans (100), Inuit (91), South East Asians (87), Native Americans (87), Pacific Islanders (85), South Asians and North Africans (84), Indians (82), non-bushmen Sub-Saharan Africans (67), Australian Aborigines (62), Bushmen and Pygmies (54). The average human IQ of the world is estimated to be 90.

Lynn defines races as the genetic clusters or ancestral population groups identified in previous genetic cluster analysis by Luigi Cavalli-Sforza and his colleagues in their 1994 book The History and Geography of Human Genes. Many current ethnic groups would be mixtures of these races. See also the Race and genetics article.

The book defends the reliability and validity of the measures. When taken as national averages, the data available, particularly regarding the developing world, is uncertain due to limited sampling, year of testing, and varying type of cognitive ability test used. Lynn argues that, though additional evidence may be required to confirm some of the racial IQ estimates, the surveyed studies have high reliability in the sense that different studies give 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. He also argues that they have high validity in the sense that they correlate highly with performance in international studies of achievement in mathematics and science and with national economic development.

Broadly speaking, Lynn estimates that about half of the IQ deficit of third world races can be explained by inadequate nutrition, while the other half is racially genetic. For example Lynn argues that while Africans living in Africa average IQ 67, African Americans living in the Southern United States (where European admixture is very low) average IQ 80. Lynn believes the latter figure represents their genotypic intelligence, while the IQs in Africa are stunted by malnutrition.

Ashkenazi Jews who Lynn classifies as West Asian/European hybrids, average 108-115 in the U.S. and Britain. Israel has an average IQ of only about 95. Lynn explains this by breaking down the Israeli population into three components: 40 percent Ashkenazi Jews (European Jewish) with an average IQ of 103; 40 percent Sephardi Jews (Oriental Jewish) with an average IQ of 91; and 20 percent Arab with an average IQ of 86. Lynn suggests these differences could have arisen from selective migration (more intelligent Jews emigrated to Britain and the USA), intermarriage with neighboring populations with different average IQs, selective survival through persecution (European Jews were the most persecuted), and the presence 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. See also the article on Ashkenazi intelligence.

Lynn argues that as early humans migrated out of Africa there was the cognitively demanding problem of cold winters with no plant food. These problems became much greater in the last ice age that began about 28,000 years ago and lasted until about 11,000 years ago. This required greater intelligence than was needed in tropical and semi-tropical equatorial Africa where plant foods are plentiful throughout the year and regulating temperature is easier. However, he writes that the Inuit, who lives in the coldest climate, do not have the highest average IQ. He explains this by a larger population density increasing the number of beneficial mutations and increasing interactions between groups of people which increases the speed by which advantageous genes can spread.