Race Differences in Intelligence: An Evolutionary Analysis - Richard Lynn

In Race Differences in Intelligence : An Evolutionary Analysis, Richard Lynn (2006) assembles a massive contribution to the IQ-hereditarian thesis. He collected a bundle of data on IQ from different populations around the world. Unfortunately, there are several questions left unclear. For instance, why is the IQ of jews so high ? In ancient times Middle-East was more advanced than western countries, while this tendency has been now reversed : there may be an explanation that fits well with hereditarian hypothesis but Richard Lynn did not cover the issue in this book (miscegenation may have played a role, according to Richard D. Fuerle, see chapter 29 of Erectus Walks Amongst Us). Among other problems, there is a strong criticism from Wicherts about the IQ of Sub-saharan Africans, although Rushton and Jensen have replied to Wicherts. Also, the reliability of Lynn's data has been vindicated by Rindermann (2007, p. 770 & 772). Lynn also believes in Out of Africa, a popular but unconvincing theory. Nevertheless the book is worth reading. For a review, see Jason Malloy (2006).

CONTENT [Jump links below]

Chapter 2. The Meaning and Formation of Races
Chapter 4. Africans
Chapter 5. Bushmen and Pygmies
Chapter 6. South Asians and North Africans
Chapter 8. Australian Aborigines
Chapter 9. Pacific Islanders
Chapter 10. East Asians
Chapter 11. Arctic Peoples
Chapter 12. Native Americans
Chapter 13. Reliability and Validity of Race Differences in Intelligence
Chapter 16. Climate, Race, Brain Size, and Intelligence
Chapter 17. The Evolution of Race Differences in Intelligence

Chapter 2. The Meaning and Formation of Races

1. The Formation of Races, Varieties, and Breeds

It is a general principle of evolutionary biology that when populations of species become isolated from one another they evolve into two or more sub-species. These are generally termed varieties, strains, or breeds. In the case of humans these different varieties are called races. These different varieties evolve as a result of the four processes of founder effects, genetic drift, mutation, and adaptation. The founder effect is that when a population splits and one group migrates to a new location to form a new population, the group that migrates will not be genetically identical to the one left behind. Hence the two populations differ genetically. The genetic drift effect is that gene frequencies change over time to some extent as a matter of chance and this leads to differences between populations. Drift continues with time and leads to increasing differences between races. The mutation effect is that new alleles (alleles are alternative forms of genes) appear through chance in some populations and if they are advantageous for survival and reproduction will gradually spread through the population. An advantageous new allele may appear as a mutation in one race, but not in others. The adaptation effect is that when a population migrates to a new location some alleles will be advantageous that were not advantageous in the old location. Individuals possessing advantageous alleles in the new location have more surviving offspring, so their alleles will be selected for and will gradually spread though the population. New varieties of several species have evolved as adaptations when populations have migrated into arctic environments. Some of these, such as foxes, bears, and hares, have evolved white fur to give them camouflage so they are not so easily seen by predators or prey. In all these cases mutations for white fur have appeared and spread through the population because they have given the animals possessing them a selective advantage. Eventually the new advantageous alleles entirely replace the less advantageous alleles and are then said to have become "fixed."

In many cases it is uncertain why different strains have evolved different characteristics. For instance, the fur of the European squirrel is red while that of the North American squirrel is grey. Possibly one of these colors confers a selective advantage and appeared by chance in one of these populations through a genetic mutation.

2. Varieties in Non-human Species

It has long been recognized that most species have several varieties or what in humans are called races. Early in his career Charles Darwin noted the different varieties of turtles on the Galapagos Islands and it was this that set him thinking how these had evolved. Later in his book The Variation of Animals and Plants under Domestication (1868) he described the different varieties of a number of species such as pigeons, each of which have their own distinctive manner of flight, movement, and cooing.

There are a number of different varieties or races among the apes. There are four races of chimpanzee. These are the true chimpanzee (Pan satyrus verus) indigenous to West Africa between Guinea and Nigeria, the bald chimpanzee (Pan satyrus satyrus) of Cameroon and Gabon, the pygmy chimpanzee (Pan satyrus paniscus) of north central Zaire, and the Schweinfurth chimpanzee (Pan satyrus schweinfurthi) of northeast Zaire. These races differ in physical appearance, distribution of blood groups, and the cries they utter. Different races have evolved among animal species in accordance with the same principles as among humans. For instance, there are two races of gorilla. These are the mountain gorilla (Gorilla beringei) native to the mountains around lakes Edward and Kivu in eastern Zaire, Rwanda, and western Uganda, and the coast gorilla (Gorilla gorilla) of the forests of Cameroon and Gabon. The two races are geographically isolated from one another by about a thousand miles and have evolved differences in physical appearance and blood group. The mountain gorilla has a narrower skull, shorter arms, longer legs, thicker hair, and blood group A, while the coast gorilla has a broader skull, longer arms, shorter legs, thinner hair, and blood group B (Baker, 1974). Some of the differences between the two races have evolved as adaptations to their different environments. The mountain gorilla inhabits a colder and open environment while the coast gorilla inhabits a warmer and densely forested environment. The mountain gorilla has developed thicker hair than the coast gorilla as a protection against the cold. The coast gorilla has developed longer arms to swing from tree to tree. There is no obvious explanation for why the mountain gorilla has a narrower skull, longer legs, and blood group A. These differences may have arisen through founder effects, genetic drift, or chance mutations, or they may confer some unknown advantage.

There are also a number of varieties among domestic animals. These are normally called breeds and have been bred by humans to serve a variety of useful purposes. Frequently they have been bred for greater size or, in the case of cattle, milk yields. In some cases they have been bred to adapt better to certain environments. For instance, varieties of hardy sheep have been bred that flourish on mountains and differ from lowland sheep. Humans have bred as many as seventy-nine different breeds of dogs for a variety of abilities, such as retrievers for retrieving game, sheep dogs for rounding up sheep, rottweilers for guarding premises, cocker spaniels for house pets, and so on. These breeds differ in their general intelligence, their specific abilities, and the ease with which they can be socialized and made obedient (Coren, 1994).

4. Race Differences in Diseases

There are race differences in a number of diseases that have a genetic basis including cystic fibrosis, PKU (phenylketonuria), hypertension, stroke, diabetes, prostate cancer, breast cancer, obesity, myopia, and schizophrenia. These differences have arisen through the processes of founder effects, genetic drift, mutation, and adaptation. There is such an extensive body of research on these that it would take a book to summarize it. The differences are illustrated here by the gene frequencies of cystic fibrosis and PKU in Europeans, sub-Saharan Africans, and East Asians (Orientals) given by Bodmer and Cavalli-Sforza (1976). These are shown in Table 2.1. The figures represent the gene frequencies (percentage prevalence rates) in the population. It will be seen that the gene frequencies of cystic fibrosis in Europeans are four or five times higher than in sub-Saharan Africans and East Asians, while gene frequencies of PKU are slightly more than twice as high in Europeans than in the other two races. The lower half of the table shows that the gene frequencies of the two diseases are quite similar in different European populations as widely dispersed as Austria, Australia, Canada, England, and the United States.

Chapter 3. Europeans

2. Europeans outside Europe

The median of these IQs is 99, the same as that of Europeans in Europe. The results show that even in the quite poor countries of Latin America (Argentina, Brazil, Colombia, Mexico, and Uruguay), which have per capita incomes about one third of those in North America and Western Europe, the IQs of Europeans are only fractionally below those in affluent nations.

Chapter 4. Africans

1. Intelligence of Africans in Sub-Saharan Africa

... Rows 6, 7, 8, 9, and 10 give IQs of 64, 68, 62, 68, and 65 for Congo-Zaire. Row 11 gives an IQ of 59 for Equatorial Guinea. Row 12 gives an IQ of 80 for adults in Ghana. The IQ is exceptionally high for sub-Saharan Africa, possibly because the sample came from the capital city of Accra; the people in capital cities typically have higher IQs than those in the rest of the country, probably because there is a tendency for more intelligent individuals to migrate to the capital; IQs in London and Paris are higher than in the rest of Britain and France (Lynn, 1979, 1980). [...]

Row 22 gives an IQ of 82 for Madagascar. Although usually counted as part of sub-Saharan Africa, the population of the island includes a significant number of Southeast Asians originally from Indonesia who migrated to the island about the first century AD (Cole, 1965). The population also contains Africans and hybrids of the two races. [...]

Row 49 gives an IQ of 78 for a sample of secondary school students in Tanzania and is exceptionally high for African samples. The author of the study explains that the reason for this is that the sample was highly selected because “the number of places in secondary school is extremely limited and eligibility is determined by competitive examination” (Klingelhofer, 1967, p. 207).

2. University Students in Africa

... Row 2 gives an IQ of 84 for African and 103 for European university students calculated in relation to American adult norms given in Raven, Court, and Raven (1994). ... Row 5 gives results for the WAIS-R for students with an average age of 25 years at the African universities of Fort Hare, Zululand, the North, and the Medical University of South Africa. The Verbal IQ was 78 and the Performance IQ 73, showing once again that the Africans have low IQs in all major cognitive abilities and disconfirming the claim sometimes made that Africans are handicapped in language tasks.

... The IQs of 100 in row 6, 93 in row 11, and 99 in row 12 are higher than the others because they are for science and engineering students who were admitted to the universities on the basis of their performance in entrance tests of mathematics and physics, and these normally have higher reasoning ability than students in most other academic disciplines. ... The results also show that IQs of African students in South Africa are on average about 20 IQ points lower than those of European students, and that a considerable gap between the IQs of Africans and Europeans remains when they are matched for years of education, African university students have had ten to twelve years of formal education but apart from those studying math and physics, obtain IQs in the range of 72-84.

4. African Americans in the United States

... It has been shown in many studies that Africans do relatively well in rests of memory, so the size of the African-European difference reflects to some degree the extent to which memory tests are represented in the IQs. For instance, one of the higher IQs in the table is the 88 obtained in Kaufman's KAIT. This test contains seven subtests, of which one is a memory for faces test that requires the identification of the faces of famous people. On this subtest Africans obtained a mean IQ of 92.5.

Second, the African-American IQ of approximately 85 appears in children aged 3, as can be seen in rows 22 and 28. These results tell against the theory often advanced by environmentalists that poor education and racism are responsible for or contribute to the low IQ of Africans. Even among 2-year-olds Africans have an IQ of 92 (row 19). This is not so low as in the other studies because African infants mature earlier than Europeans up to the age of two years (Lynn, 1998d; Rushton, 2000). It is not until their third year that their IQs fall below that of Europeans and only in their fourth year that their IQ declines to reach their IQ of approximately 85, as shown in rows 22 and 28.

5. Africans in Britain

... Row 15 gives an IQ of 86 obtained by West Indian children at school in a town in the Midlands; Indians from the Indian sub-continent attending the same schools obtained an IQ of 96, showing once again that South Asians in the same environment as Africans obtain higher IQs.

... Second, the higher IQ of Africans in Britain is attributable to the better environment. This effect is shown in the study by Yule, Berger, Rutter, and Yule (1975) given in rows 7 and 8 showing IQs of 73 for those born in the West Indies and 82 for those born in Britain, suggesting that residence in Britain raises the IQs of Caribbean children by around 9 IQ points. This result is confirmed by the Mackintosh and Mascie-Taylor (1985) study shown in row 18, where the West Indian children from the Caribbean who had been in Britain for more than 4 years had an IQ of 89, while the IQ of a further group of 39 who had been in Britain for fewer than 4 years obtained an IQ of 83, suggesting that residence in Britain raises the IQs of Caribbean children by around 6 IQ points. ... Third, the IQ of 87 for a sample of West Indian 4-year-olds given in row 17 is virtually exactly the same as that obtained by older West Indian children at school and shows that the low IQs of West Indian children cannot be blamed on schools, prejudice of teachers, difficulties understanding teachers’ spoken English, and so on.

6. Africans in the Netherlands

... Row 2 gives an IQ of 84 for a sample of the children of first generation immigrants from Surinam and the Netherlands Antilles. Row 3 gives an IQ of 88 for a sample of the children of second-generation immigrants from Surinam and the Netherlands Antilles. These children have a four-IQ-point gain compared with the children of first generation immigrants shown in row 2. This confirms the studies in Britain showing that second generation immigrants obtain higher IQs than first generation.

8. Short-Term Memory and Perceptual Speed Abilities of Africans

... Short-term memory is typically measured by the Digit Span test, consisting of the ability to recall a series of numbers either in the order in which they are presented (forward Digit Span) or in reverse order (backward Digit Span). Perceptual Speed is typically measured by the Coding and Digit Symbol subtests in the Wechsler tests that require accurate and rapid scanning of visual information. These studies have shown that Africans have relatively strong short-term memory and perceptual speed abilities. The results are summarized in Table 4.7. Row 1 gives IQs of 75 and 76 for African 10-12-year-olds (n=1,123) compared with Europeans (n=1,489) obtained for non-verbal reasoning and for verbal ability measured by the Lorge-Thorndike test, a much higher IQ of 90 for short-term memory measured by Digit Span and a remarkable IQ of 102 for Perceptual Speed. The authors comment: "given a test that involves only speed but no appreciable cognitive factor, the Negro children perform as well as or better than the European children" (Jensen & Rohwer, 1970, p. 60). ... It will be seen that the African short-term memory IQ (79) and the per-ceptual speed IQ (69) are both higher than their Abstract Reasoning Ability (58) and their Verbal Reasoning Ability (63), confirming the American studies. [...]

Jensen (1998) has interpreted these and other results as showing that the African-European differences in intelligence are largely differences in Spearman's g. According to this theory, short-term memory and perceptual speed are weak measures of g, so Africans do relatively well on them. The theory has received considerable support, summarized by Rushton (2003), but has also attracted some criticism from Dolan and Hamaker (2001).

9. Musical Abilities

Musical abilities are measured by simple tests such as the identification of pitch change (identifying whether the pitch of one tone is higher or lower than that of another; in the initial items the difference between the tones is great but as the test progresses the tones become closer until it is extremely difficult to distinguish which is higher); memory (a tune is played twice and on the second playing one note is altered; the task is to identify the altered note); chord analysis (the identification of the number of notes in a chord); and rhythm (two pieces of music are played and the problem is to identify whether the rhythms are the same or different). The association between intelligence and musical ability has been shown in two studies carried out by Lynn, Wilson, and Gault (1986). In the first, a sample of 217 10-year-olds were given a number of tests of reasoning, vocabulary, visualization, and perceptual speed abilities together with four musical ability tests (pitch, memory, chords, and rhythm). All the tests were positively intercorrelated and loaded on the first principal component as a measure of general intelligence (g). The loadings of the four musical tests lay between 0.45 (cords) and 0.59 (rhythm). This shows that the musical tests are measures of g. In the second study 93 9-11-year-olds were given three tests of musical ability (pitch change, chord analysis, and memory) together with the Standard Progressive Matrices, a measure of g. The three musical tests were significantly correlated with the Progressive Matrices at 0.27, 0.40, and 0.37. This confirms that musical ability is associated with intelligence. Further evidence for this associa­tion has been provided by Carroll (1993).

... The general outcome of these studies is that African Americans perform less well than Europeans on tests of musical abilities of pitch discrimination, tone discrimination, and memory, but they perform about the same as Europeans on tests of rhythm.

11. Brain Size of Africans and Europeans

... Row 7 gives results for the United States for military personnel. These figures are adjusted for height and weight. The brain sizes of the Europeans are virtually identical to those found by Ho et al. given in row 4, but the brain size of the Africans is much greater, at 1,359 as compared with 1,267. The explanation for this is that the U.S. military screens applicants for intelligence and rejects those with IQs below 81 (Nyborg and Jensen, 2000). Flynn (1980) has estimated that military rejection rates for low IQ are 3.4 percent for Europeans and 30 percent for Africans, and that the result of this is that Africans in the military have an average IQ of 91.5. The effect of not accepting Africans with low IQs is to screen out many of those with low intelligence and small brains, making the African-European brain size difference much smaller than in other samples.

14.  Genetic and Environmental Explanations of the Low African IQ

... These egalitarians do not explain how hypothetical white racism could impair the IQs of black children reared by middle class white parents. There is no known or plausible mechanism by which supposed white racism could impair the IQs of blacks. Nor do they attempt to explain how it is that Africans throughout sub-Saharan Africa, who are not exposed to white racism, except in South Africa, have IQs of approximately 67.

Furthermore, if racism lowers intelligence, it is remarkable that Jews in the United States and Britain should have IQs of around 108, as shown in Lynn (2004), since Jews have been exposed to some degree of racism for many centuries.

... While the results of this study show that differences in family environment cannot explain the low black IQ, it remains possible that blacks provide an inferior prenatal environment as a result of poorer nutrition of pregnant black women or possibly of the greater use of cigarettes that might impair the growth of the fetal brain. These possibilities are rendered improbable by studies showing that the nutrition of American blacks throughout the twentieth century was not inferior to that of whites (see Chapter 13, Section 7). Another possibility is that black babies might suffer greater impairment of the brain because pregnant black women might smoke cigarettes more, since there is some evidence that smoking retards fetal growth, but this is rendered improbable by numerous studies showing that blacks smoke cigarettes less than whites.

15. Estimation of the Genotypic African IQ

... A further argument for believing that the IQ of African Americans is wholly genetically determined is that it has remained constant over a period of approximately 80 years despite the great improvements in the environment of African Americans relative to that of Europeans.

The conclusion that African Americans have a genotypic IQ of 85 does not mean that Africans in sub-Saharan Africa also have a genotypic IQ of 85. African Americans are not pure Africans but are a hybrid population with a significant amount of European ancestry. This has been estimated at 25 percent by Reed (1971) and by Chakraborty, Kamboh, Nwamko, and Ferrell (1992). We can estimate that pure Africans in Africa and in the United States have a genotypic IQ of 80 and that this IQ increases by 0.2 IQ points for every 1 percent of Caucasoid genes. Thus, the average African American will have an IQ of 85 (80 + 25 X 0.2 = 85), a figure confirmed by numerous studies summarized in Table 4.4. In the Southeastern states the percentage of European genes among African Americans is quite low. For instance in South Carolina it has been estimated at 6 percent (Workman, 1968) and in Georgia at 11 percent (Reed, 1969). These admixtures of European genes should raise their IQ by 1.2 and 2.2 IQ points, respectively, giving them an IQ of 81.2 and 82.2. This prediction has been confirmed by the study of 1,800 African Americans in five Southeastern states by Kennedy, Van der Reit, and White (1963), which found their IQ on the 1960 Stanford-Binet was 80.7.

African Americans with 50 percent European genes will have an IQ of 90 (80 + {50 by 0.2 = 10} = 90). This is about the mean IQ of African Americans in the Northern states, where the proportion of European ancestry approaches 50 percent.

Chapter 5. Bushmen and Pygmies

The Bushmen have a number of physical characteristics that distinguish them from Negroid Africans. They have peppercorn hair that grows in spirals with open spaces between tufts, whereas most Africans have helical woolly hair that forms a tight mat. It is believed that the peppercorn hair of the Bushmen evolved as an adaptation in hot and damp forests in which they lived for many millennia because it affords protection from strong sunlight but at the same time the open spaces between the tufts allow sweat to evaporate. Pygmies who have remained in tropical rain forests have the same peppercorn hair. The mat woolly hair of Negroid Africans is a more advantageous adaptation in dry hot environments because it gives greater protection from strong sunlight and reduces sweating. The skin color of the Bushmen is yellowish brown, while that of Negroid Africans is black or dark. Some of the Bushmen have an epicanthic fold on the upper eyelid, similar to but less pronounced than that of East Asians and Arctic Peoples. The advantage of the epicanthic fold for Bushmen is probably that it reduces the dazzling effect of glare from strong sunlight reflected from the desert, as it does the glare from snow for the East Asians and Arctic Peoples. This characteristic must have arisen independently through convergent evolution.

3. Pygmies

... Most of the Pygmies have remained hunter-gatherers. Typically they live in small groups of around 30 and move from place to place. They have made no progress in the domestication of either animals or plants. In the early twenty-first century the Pygmies in the Congo were described by Cheung (2003) as living "deep in the forests, eking out an existence by hunting and gathering food."

Only one study has been made of the intelligence of Pygmies. This was carried out by Woodworth (1910) using the Sequin Form Board test, which consists of a set of blocks of various shapes that have to be fitted into the appropriate holes. He found that Pygmies performed much worse than other peoples including Eskimos, Native Americans, and Filipinos but he did not quantify their abilities. Judging from their life-style, their intelligence appears to be lower than that of Negroid Africans. Most of them still retain a primitive hunter-gatherer existence while many of the Negroid Africans became farmers during the last few hundred years. In the twentieth century a number of Pygmies worked for Negroid African farmers and these "are always the lower caste, being the farmers' hereditary servants," according to Cavalli-Sforza, Menozzi, and Piazza (1994, p. 178). The term "hereditary servants" appears to be a euphemism for slaves. The enslavement of Pygmies by Negroid Africans is consistent with the general principle that the more intelligent races typically defeat and enslave the less intelligent, just as Europeans and South Asians have frequently enslaved Africans but not vice versa.

Chapter 6. South Asians and North Africans

1. Intelligence of Indigenous South Asians and North Africans

... The median IQ of 90 derived from the three studies for Turkey is higher than that in the remainder of South Asia and North Africa. The most likely explanation for this is that Turkey has straddled Europe and Asia for many centuries and the geographical proximity of Turkey and southeast Europe will have brought about a mixing of Turkish and European genes to produce a European-South Asian cline or genetically hybrid mixed population, with the result that contemporary Turks and Greeks are genetically quite similar, as shown by Cavalli-Sforza, Menozzi, and Piazza (1994) and noted in Chapter 3.

4. Indians in Africa, Fiji, Malaysia, and Mauritius

The median IQ of Indians in South Africa derived from the five studies is 86. This is a little higher than the median IQ of 82 of Indians in India and a little lower than the IQ of approximately 89 of Indians born in Britain. Possibly a reason for these differences is that standards of living are lowest in India, higher in South Africa, and highest in Britain, and these have had some effect on intelligence levels. There may also have been differences in the intelligence of the migrants from whom the Indians in South Africa and Britain are descended. The ancestors of the Indians in South Africa were largely recruited to work in the sugar and tobacco plantations and may not have had such high IQs as those who migrated to Britain in the second half of the twentieth century.

Row 6 gives an IQ of 91 for Indians in Tanzania. The sample consisted of secondary school students who had to pass an entrance examination for entry to their schools and the IQ is therefore somewhat inflated. The IQ of this sample is probably about 8 IQ points higher than that of the general population of Indians in Tanzania, which can therefore be estimated at approximately 83, closely similar to the IQ of 82 of Indians in India given in Table 6.1. In the same study Africans at the same selective schools obtained an IQ of 78. This difference confirms a number of studies in South Africa and Britain showing that when Indians and Africans are in the same environment, Indians obtain substantially higher IQs than Africans.

5. High School and University Students

Rows 9 and 10 give IQs of 98 and 102 for engineering students at the University of the Witwatersrand in South Africa. In this study European students in the same faculty obtained IQs of 106 and 113, and black African students IQs of 93 and 99. Row 11 gives an IQ of 106 for a further sample of engineering students at the University of the Witwatersrand in South Africa. In this study European students in the same faculty obtained an IQ of 116, and black African students an IQ of 101.

9. Intelligence in Israel

A second problem concerning the intelligence of Jews is that all Jews were originally from the same stock, so why is the intelligence of Ashkenazim Jews approximately 12 IQ points higher than that of Oriental Jews? There are probably two answers to this question. The first is that despite strict Jewish prohibitions on exogamy, there has always been some inter-marriage and inter-mating between Jews and non-Jews living in the same localities. Even a small amount of exogamy over many generations is sufficient to introduce significant proportions of non-Jewish genes into the Jewish gene pool. The effects of this are visible in European Jews, a number of whom have fair hair and blue eyes. The result of this will have been that Ashkenazim Jews in Europe will have absorbed a significant proportion of the genes for higher intelligence possessed by the Europeans, while the Oriental Jews in the Near East and North Africa will have absorbed a significant proportion of the genes for lower intelligence from the South Asians and North Africans. The second factor that has probably operated to increase the intelligence of Ashkenazim Jews in Europe and the United States as compared with Oriental Jews is that the Ashkenazim Jews have been more subject to persecution. Jews were less persecuted over the course of many centuries in Southwest Asia and North Africa. Oriental Jews experienced some persecution sufficient to raise their IQ of 91, as compared with 84 among other South Asians and North Africans, but not so much as that experienced by Ashkenazim Jews in Europe.

Chapter 8. Australian Aborigines

4. Spatial Memory

A remarkable study by Kearins (1981) found that Aboriginal children had much stronger spatial memory than Europeans. In this study 132 Aboriginal children aged 7-16 and the same number of white Australian children were given various tests of spatial memory. The general format of the tests was that 20 objects were laid out and the child was asked to look at them for 30 seconds and try to remember their position. The objects were then removed and the child was asked to re-assemble them in the same positions. In all the tasks Aboriginal children performed better than whites. Their overall advantage is represented by a Spatial Memory IQ of 119. Kearins argued that the most probable explanation for this high spatial memory ability is that it evolved in the Aborigines because the deserts of central Australia have few landmarks and the nomadic Aboriginal peoples needed to note and remember the location of such landmarks as exist to construct mental spatial maps of their environments to find their way home after going out on hunting expeditions. In support of this argument, she tested a sample of Aborigines living in a town whose families had been living in the town for several generations. This group performed just as well on spatial memory as those from the desert. She argued that this indicated that the environment is not responsible for the high spatial memory ability of the Aborigines and supported her view that it has an evolved genetic basis.

Kearins's results have, however, been challenged. Drinkwater (1976) compared 22 Aboriginal and 22 white 12-year-olds on similar tasks and found the two groups performed at the same level, but his Aborigines came from a coastal area where the strong spatial memory required according to Kearins's theory would not have been necessary and would not have evolved. Nevertheless, considering the low general intelligence of Aboriginals, it is remarkable that they should have performed as well as whites on spatial memory. Harris (1977) in an unpublished Ph.D. thesis found that desert Aborigines performed worse than whites on this task. Knapp and Seagrim (1981) also found that desert Aborigines performed worse than whites, but unfortunately they did not present the data in such a way that the magnitude of the white advantage can be calculated. Despite these negative results Kearins's findings on the Aboriginal spatial memory remain impressive and deserve further research by Australian psychologists. The strong spatial memory of the Aborigines, if it can be confirmed, has a parallel in the strong visual memory of the Eskimos reported by Kleinfeld (1971) and explained as an adaptation to living in the frozen tundra, which contains few landmarks and is similar in this regard to the deserts of Australia (see Chapter 11).

6. Genotypic Intelligence of Australian Aborigines

First, the most satisfactory method for assessing the extent to which genetic factors are involved in the low intelligence of the Aborigines would be a cross-racial adoption study in which Aboriginal infants are adopted by white families. Environmental theory predicts they will have the same aver age IQ as whites, while genetic theory predicts their IQ will remain the same as that of Aborigines. If their average IQ is intermediate between that of Aborigines and whites it can be inferred that both genetic and environmental factors are involved. The only study of this kind that has been carried out is by Dasen, de Lacey, and Seagrim (1973) and concerned 35 Aboriginal children adopted by white couples in and around Adelaide. Seventeen of these children were half Aborigine and the remainder were 7 full-blooded, 2 three-quarter, 4 one-quarter, one one-eighth and 4 unknown. On average they were about half Aborigine. The average age of adoption was 18 months. Between the ages of 5 and 13 years they were given six tests, of which four were Piagetian, one was the Nixon test of "reclassification," and the other was the Peabody Picture Vocabulary Test. The results are given for the adopted Aborigines, and for comparison groups of Europeans and full-blooded Aborigines in central Australia. None of the test results can be accurately quantified because they are given in graph format. It can be discerned from these that on two of the Piagetian tests (conservation of quantity and weight) the Aborigines performed about mid-way between Europeans and full-blooded Aborigines. As the adopted Aborigines were half-blooded, this is where they would be expected to fall and the results suggest that the adoptive experience had no advantageous effect. On the third test (conservation of horizontality) the adopted Aborigines performed somewhat below the European comparison group but substantially better than the full-blooded Aborigines. On the fourth, fifth, and sixth tests, described as measures of "sedation of lengths," "reclassification" (neither of these terms is explained), and the PPVT, the Aborigines performed about the same as the European comparison group. Thus, while the performance of these adopted part-Aboriginal children varied on the different tests, on the tests considered as a whole they scored below European children. This is consistent with the authors' observation that "the majority of the children were reported, by their parents, to be below average in school work; most were reported to experience particular difficulty in mathematics" (p. 98). While these adopted part-Aborigines performed at a lower level than Europeans they seem to have performed somewhat better than part-Aborigines reared by their biological parents. The results therefore suggest that both genetic and environmental factors are responsible for the low intelligence of Aborigines. It should be noted that the average age of the children when they were tested was about 8 years and that the American study by Weinberg, Scarr, and Waldman (1992) of black children adopted by white parents found that at the age of 7 years they had an average IQ of 95 but by the age of 17 this had deteriorated to 89, showing young black children secure IQ gains from adoption but these fade by late adolescence (see Chapter 4). [...]

Third, all the Aboriginal children in the studies listed in Tables 8.1 and 8.2 attended schools and in three of the studies (rows 6, 7, and 9 in Table 8.l) the Aboriginal children attended schools with white children, so their low IQs cannot be attributed to lack of opportunity to acquire the mental skills tested in intelligence tests or to radically different environments. [...]

Sixth, there is no tendency for the IQs of Aborigines to increase over the period of approximately half a century from the first two studies carried out around 1930 that produced IQs of 66 and 59, and the last two studies carried in the 1980s and 1990s that produced IQs of 60 and 61 (see Table 8.1), despite improvements in the environmental conditions of Aborigines arising from increased welfare and medical attention.

Seventh, if the intelligence of some Aborigines is impaired by adverse environmental conditions the most probable factor is likely to be poor nutrition. The prevalence of malnutrition among Aborigines has been investigated in two studies. In the first, Edwards (1970) in a study of 82 preschool Aboriginal children in New South Wales found that 31 percent were malnourished and in a subsequent study of 281 Aboriginal children that 21 percent were malnourished (Edwards and Craddock, 1973). Malnourishment in infancy has an adverse effect on intelligence, but these two studies taken together found that only approximately 25 percent of Aborigines are affected. Edwards and Craddock (1973) administered an intelligence test to 29 malnourished and 29 well-nourished Aboriginal children aged 6 to 10 years and found that the malnourished children had a mean IQ 8 IQ points lower than the well nourished. As approximately 25 percent of Aborigines are malnourished, the effect of malnutrition on the total Aboriginal population would be to reduce the IQ by about 2 IQ points. This suggests that inadequate nutrition has only a negligible effect on the low IQ of Aborigines.

Chapter 9. Pacific Islanders

2. Other Pacific Islanders

... The median IQ of the Pacific Islanders other than New Zealand Maoris is 85 and is therefore slightly lower than the median of 90 of the Maoris. The explanation for the higher intelligence of the Maoris is that many of them interbred with Europeans and that they enjoy higher living standards and health care than other Pacific Islanders.

5.  Environmental and Genetic Determinants of the Intelligence of Pacific Islanders

... The Maoris in New Zealand and the Hawaiians in Hawaii have approximately the same environment as Europeans in so far as they enjoy the environmental advantages of living in affluent European societies with high standards of nutrition, education, and welfare. The IQ of 90 of the Maoris is higher than the 85 of the other Pacific Islanders, suggesting a beneficial effect of living in an affluent European environment, but it remains well below the IQ of Europeans. The average IQ of the four studies of the native Hawaiians is 84, virtually the same as the 85 of other Pacific Islanders, suggesting that the affluent environment of Hawaii does not improve their intelligence. The brain size of the Pacific Islanders is about 4 percent smaller than that of Europeans and probably has some genetic basis, contributing to the intelligence difference.

Chapter 10. East Asians

2. East Asians in the United States

The median IQ of the nine studies in the first half of the twentieth century is 101 and is a little lower than the median of 104 of the nine studies obtained from 1980 onwards, when it is almost exactly the same as the 105 of indigenous East Asians. There are three possible explanations for the increase in the intelligence of East Asians in the United States during the twentieth century. The first is that many of those in the early studies spoke Chinese or Japanese as their first language and would have been handicapped on tests in English. Second, there may have been a tendency for the East Asians who migrated to the United States to have been a little below the average intelligence of those who remained in East Asia. The Chinese and Japanese who emigrated to the United States in the second half of the nineteenth century were largely peasants who came to do unskilled work on the construction of the railways and other building work. This would probably not seem an attractive option for the more intelligent who would generally have been doing sufficiently well in their own countries. Once these early migrants had settled in the United States their children would have shown some regression upwards towards the East Asian mean of 105.

10. Environmental and Genetic Explanations of the East Asian IQ

In Table 10.3 we see that East Asians consistently obtain slightly higher average IQs than Europeans in similar environments. In Brazil, the IQ of 99 of ethnic Japanese is 4 IQ points higher than that of Europeans (see Table 3.2), although the Japanese were brought in to work as agricultural laborers after the abolition of slavery in 1888 and are unlikely to have had higher IQs than the general population in Japan. In Britain, East Asians obtained an IQ of 107, and in the Netherlands an IQ of 102. In Malaysia, they obtain an IQ of 99, 10 IQ points higher than that of the indigenous Malays.

Third, environmentalists do not offer any explanation for the consis­tently high IQ of East Asians, and it is doubtful whether any credible environmental explanation can be found. Intelligence is affected by living standards, but the living standards of a number of East Asians have been lower than those of Europeans. The East Asians of Japan, Hong Kong, and Singapore enjoy comparable living standards to those of Europeans in northern and western Europe, the United States, Canada, Australia, and New Zealand, but the living standards of those in China, South Korea, and Taiwan have been much lower, yet their IQs are about 5 IQ points higher than those of Europeans. [...]

Fifth, the faster reaction times of East Asian children shown in Table 10.6 indicate that they have a more efficient neurological processing system that makes a significant contribution to their higher IQs, and again this superiority in reaction times cannot be plausibly explained environmentally.

Chapter 11. Arctic Peoples

2. Visual Memory

It is likely that the strong visual memory of Inuit has a genetic basis. It has been found by Osborne and Gregor (1966) that visual memory has a high heritability. Even 9-year-old Inuit children had significantly better visual memory than Europeans, and it seems unlikely that children of this young age would have acquired this strong ability through training, even if this is possible. The most probable explanation for the strong visual memory of Inuit children is that this ability developed genetically through natural selection because of the need for Arctic Peoples to remember fine details of the landscape in order to find their way home after going out on long hunting expeditions. The landscape of the frozen tundra provides few distinctive cues, so hunters would need to note and remember such few features as do exist. The strong visual memory of the Inuit is also present in the East Asians (IQ 107) (Chapter 10, Section 7) and Native Americans, for whom Lombardi (1970) found an IQ of 104, very close to the IQ of 106 found by Kleinfeld for Inuit. Possibly the ancestral population of northeast Asia evolved strong visual memory before they diverged into the East Asians, Native Americans, and Arctic Peoples.

Chapter 12. Native Americans

9. Genotypic Intelligence of Native Americans

The low intelligence of Native Americans is most reasonably attributable to both genetic and environmental factors. There are four lines of evidence pointing to some genetic determination. First, only between 20 and 30 percent of Native Americans in South and Central America have nutritional deficiencies that could explain their low IQs. Second, the intelligence of Native Americans in the United States and Canada has shown no improvement relative to that of Europeans since the 1920s, despite great improvements in their living standards and environments. Third, the intelligence of Native American-European hybrids is related to the amount of European ancestry, shown in Section 5. Fourth, Hispanics are largely Native American-European hybrids, and their intelligence is intermediate between the two parent races. Fifth, a study by Cundick, Gottfredson, and Willson (1974) showed that 84 Native American children placed in white middle-class foster homes for a period of six years made no gains in intelligence. This shows that the various environmental advantages associated with being reared in a white middle class family have no beneficial effect on the intelligence of Native Americans and suggests that their IQ is to some degree genetically determined.

Chapter 13. Reliability and Validity of Race Differences in Intelligence

1. Summary of Race Differences in Intelligence

... Row 16 gives an IQ of 87 for indigenous Southeast Asians derived from 11 samples in 6 counties. Row 17 gives an IQ of 93 for Southeast Asians in the United States and the Netherlands. The reason that this is higher than in Southeast Asia is probably that there has been some selective migration and that living standards are higher.

5. Validity of Racial IQ Data: Per Capita Income and Economic Growth

The validity of race differences in IQs has been examined by extending this law to races. In Lynn and Vanhanen (2002) we have estimated IQs for all the 185 nations in the world with populations over 50,000. These national IQs are determined by the racial composition of the populations, as shown in the last section. We found that the national IQs are correlated at 0.62 with real GDP (Gross Domestic Product) per capita in 1998 and at 0.63 with GNP (Gross National Product) per capita in 1998. This shows that national IQs explain 38 percent and 32 percent, respectively, of the variance in per capita GDP and GNP. The correlations are not huge because national per capita incomes are significantly determined by other factors, of which the most important are the possession of natural resources and the presence of a market economy. Thus, for instance, the real GDP per capita in 1998 in Qatar (IQ=78) was $20,987, about the same as that in Britain ($20,336), and much higher than that in countries in south Asia with about the same IQ but no natural resources, such as India (IQ=82, GDP=$2,077) and Jordan (IQ=84, GDP=$3,347). The reason for the high GDP in Qatar lies in the possession of oil, which is not possessed by India or Jordan. The second major factor determining national incomes is the presence of a market economy. Thus, the countries of Eastern Europe have about the same IQs as those of Western Europe but they have much lower per capita incomes (e.g., Russia $6,460 and Poland $7,619), as compared with Britain ($20,336) and France ($20,846). Similarly, the per capita income in China ($3,105 in 1998) is much lower than in Hong Kong ($20,763) and Singapore ($24,210), although the people are all or mainly Chinese and have closely similar IQs (China, 103; Hong Kong, 107; Singapore, 103). The reason for this is that economic development in China has been retarded by the communist economy while that in Hong Kong and Singapore has been facilitated by market economies. In the countries taken together, the extent to which they have market economies measured by the index of economic freedom is correlated at 0.71 with real GDP per capita (1998), slightly higher than the correlation of IQ with real GDP per capita in 1998 (0.62), showing both economic freedom and IQs contribute substantially to national wealth. Economic freedom was correlated at 0.64 with real GNP per capita in 1998, as compared to the correlation of 0.63 between national IQs and GNP per capita.

There are also significant associations between national IQs and the rate of economic growth during the twentieth century. Thus, the correlation of national IQ and growth of GDP from 1950 to 1990 is 0.51. This shows that the countries with higher IQs are becoming more affluent and the gap between rich high IQ countries and poor low IQ countries is increasing. This is as would be expected because economic growth is driven by new high technology products such as computers, mobile phones, pharmaceuticals, aircraft, weapons, automobiles, and so forth, which can only be designed by peoples with high IQs. Nations with low IQs earn their living principally by the export of agricultural products, raw materials, and minerals for which there is less demand and prices are lower, so their economic growth rates and per capita incomes remain low.

Chapter 16. Climate, Race, Brain Size, and Intelligence

2. Cognitive Demands in Northern Latitudes

The selection pressure for enhanced intelligence acting on the peoples who migrated from tropical and sub-tropical equatorial Africa into North Africa, Asia, Europe, and America was the problem of survival during the winter and spring in temperate and cold climates. This was a new and more cognitively demanding environment because of the need to hunt large animals for food and to keep warm, which required the building of shelters and making fires and clothing. In addition, Miller (2005) has proposed that in temperate and cold climates females became dependent on males for provisioning them with food because they were unable to hunt, whereas in the tropics women were able to gather plant foods for themselves. For this women would have required higher intelligence to select as mates the men who would provision them. For all these reasons temperate and cold climates would have exerted selection pressure for higher intelligence. The colder the winters the stronger this selection pressure would have been and the higher the intelligence that evolved. This explains the broad association between latitude or, more precisely, the coldness of winter temperatures and the intelligence of the races.

The theory that race differences in intelligence evolved because the peo ples who migrated out of Africa into the temperate and cold climates of Asia and Europe entered a more cognitively demanding niche that required greater intelligence is a further instance of the general principle that had operated in the evolution of greater intelligence in mammals when they colonized the nocturnal niche, birds when they colonized the air, monkeys and apes when they became co-operating social animals, and hominids when they adapted to the open savannah. The new niche of the temperate and cold environments colonized by the races that migrated out of Africa demanded an adaptation from an herbivorous to a largely carnivorous life style. The primates from whom humans evolved had lived for a period of approximately 60 million years as herbivores in the tropical and sub-tropical environment of equatorial Africa, in which plant foods are available throughout the year. The hominids that evolved in equatorial East Africa remained largely herbivorous. In contemporary times hunter-gatherer peoples in tropical and subtropical latitudes continue to subsist largely on plant foods, of which numerous species are available throughout the year (Lee, 1968; Tooby and de Vore, 1989).

Because primates are adapted as herbivores in tropical and sub-tropical environments they have found it difficult to survive in temperate environments in which plant foods are not available for a number of months in the winter and spring. An early instance of primates encountering the problem of survival during the winter and spring in temperate environments occurred during the mid-Miocene between 16 and 14 million years ago. This was a warm period in which much of Eurasia became subtropical. Two species of apes, Pliopithecus and Dryopithecus, migrated from Africa into Eurasia and flourished there. At the end of this period, about 14 million years ago, Eurasia became colder and the climate became temperate. In Europe and in most of Asia these apes were unable to survive during the winters and became extinct. The only part of Asia where these early apes were able to survive was in the tropical southeast and the Indonesian archipelago, where they evolved into the orangutans and gibbons (Pickford, 1986).

7. Sex Differences in Intelligence and Brain Size

... This advantage is wholly explicable by the larger male brain, as would be expected because males and females experience the same environment and therefore environmental factors cannot account for the male-female difference. The explanation in evolutionary terms for the greater average intelligence of men is probably that in most social species males compete with one another to obtain female mates and in the evolution of the hominids intelligence came to play a significant role in success in this competition. Females do not compete for male mates to anything like the same extent. This would have exerted stronger selection pressure for enhanced intelligence in men than in women.

8. Genetical Processes in the Evolution of Race Differences in IQ

... The early humans that migrated out of Africa and spread throughout the world would have carried all the alleles for high and low intelligence with them, but those who colonized Asia and Europe were exposed to the cognitively demanding problems of survival during cold winters. Many of those carrying the alleles for low intelligence would have been unable to survive during the cold winters and the less intelligent individuals and tribes would have died out, leaving as survivors the more intelligent. This process would have reduced and possibly eliminated the alleles for low intelligence, leaving a higher proportion of the alleles for high intelligence. The more severe the winter temperatures, the greater the selection pressure for the elimination of low IQ individuals carrying low IQ alleles. This process explains the broad association between coldest winter temperatures and IQs and brain size shown in Table 16.2.

A parallel genetical process must have been involved in the evolution of race differences in skin color. The first humans who evolved in tropical equatorial Africa must have had black or very dark skins, as these peoples do today, because of the adaptive advantage of dark skin in strong sunlight. When some of these early peoples migrated into North Africa, Asia, and Europe, alleles for paler skins must have appeared as mutations. Individuals with these mutations would have had a selective advantage because they could synthesize vitamin D from sunlight, while at the same time they did not suffer the disadvantage of contracting skin cancer from the excessively strong sunlight of the tropics. Hence, individuals with paler skins left more surviving offspring, with the result that the alleles for paler skins spread through the population and eventually replaced the alleles for dark skin. This process produced the same broad gradient for skin color as evolved for intelligence, with the Arctic peoples, East Asians, and Europeans having evolved the palest skins, the South Asians and North Africans, Native Americans, Southeast Asians, and Pacific Islanders having evolved somewhat paler skins, while the Africans, Bushmen, and Australian Aborigines exposed to the strongest sunlight retained the darkest skins.

A second genetical process has been proposed by Miller (1996, 2005), in which several new alleles for high intelligence appeared as mutations in some races but did not appear in others, and these were never transmitted to some other races. This assumption is necessary to explain some of the anomalies in the general relationship between severe winters and the race differences in intelligence. The general principles are that new mutant alleles for high intelligence would be most likely to appear in large populations and in populations that are subjected to stress. New mutant alleles for high intelligence would be most likely to appear in large populations because a mutation is a chance genetic event and hence is more likely to occur in races with large populations. In addition, populations subjected to stress, including extreme temperatures, also experience more mutations (Plomin, DeFries, and McClearn, 1990, p. 91). The effect of these two principles is that mutations for higher intelligence would have been more likely to occur and can be assumed to have occurred more frequently in the South Asians, who had large populations and were subjected to cold stress, and particularly in the East Asians and Europeans, who had large populations and were subjected to extreme cold stress, than in the Africans, who had a large population but were not subjected to extreme cold stress, and in the Australian Aborigines and Bushmen, who had small populations and were not subjected to extreme cold stress. The Arctic Peoples were subject to extreme cold stress but comprised very small populations, so they would be unlikely to have had mutations for higher intelligence. [...]

Once a new mutant allele for higher intelligence had appeared it would confer a selection advantage and would have spread throughout the group of around 50 to 80 individuals in which people lived during the hunter-gatherer stage of human evolution. It would then have spread fairly rapidly to adjacent groups because hunter-peoples typically have alliances with neighboring groups with which they exchange mating partners, and it is reasonable to assume that this custom was present for many thousands of years during the evolution of the races. These alliances of groups are known as demes, and a new mutant allele for higher intelligence and which conferred a selection advantage would have spread fairly rapidly through a deme.

Chapter 17. The Evolution of Race Differences in Intelligence

1. Africans

The ready availability of plant foods, insects, and eggs throughout the year meant that the evolving African peoples in tropical and sub-tropical Africa did not have to hunt animals to obtain meat. A conference of anthropologists was convened in 1966 to debate the Man the Hunter thesis of the importance of hunting for contemporary hunter-gatherers, at which "the consensus of opinion was that meat is of relatively little nutritional importance in the diets of modern tropical foragers" (Stanford and Bunn, 2001, p. 4). In 1999 a similar conference took place at which there was "a consensus that hominid diets were primarily plant based, as they are among modern tropical foragers" (Stanford and Bunn, 2001, p. 356). Hence the Africans had no need to develop the intelligence, skills, tools, and weapons needed for hunting large mammals. Furthermore, the temperature of equatorial Africa varies annually between approximately 32°C. in the hottest month and 17°C. in the coldest, so the African peoples did not encounter the cog­nitively demanding requirements of having to make needles and thread for making clothes and tents, to make fires and keep them alight, or to prepare and store food for future consumption. It was relatively easy to keep babies, infants, and young children alive because there was no need to provide them with clothing and from quite a young age they were capable of going out and foraging for food by themselves.

Nevertheless, the brain size of the Africans increased during the last 200,000 or so years from approximately 1,186 to 1,276cc, and it can be reasonably assumed that this entailed an increase in their intelligence to its contemporary value of 67. This increase occurred because of continual directional selection for intelligence, i.e., the more intelligent individuals had more surviving offspring. The genetical processes will have consisted of the increase in the frequencies of the alleles for higher IQs and probably of some mutations for higher intelligence.

2. Bushmen

... It has been reported by Stahl (1984) that Bushmen eat around 90 different plant foods and these constitute 70-85 percent of their diet. Hence, they were not exposed to the cognitive demands of survival in a cold temperate environment.

3. South Asians and North Africans

... The major source of food, therefore, became large mammals such as antelope, deer, horses, and boars that people had to hunt to secure food supplies. ... Hunting in open grasslands is more difficult than in the woodlands of the tropics and sub-tropics, where there is plenty of cover for hunters to hide in. The humans that evolved in equatorial Africa were largely herbivorous and were not adapted for hunting large mammals, so this would have presented new cognitive problems for them. Large herbivores can run fast and are virtually impossible to catch simply by chasing after them. The only way of killing these animals was to make use of natural traps into which the animals could be driven and then killed. [...]

Peoples in cold environments need more tools of different kinds and greater complexity than peoples in tropical and sub-tropical environments. This has been shown by Torrence (1983), who has demonstrated an association between latitude and the number and complexity of tools used by contemporary hunter-gatherers. He found that hunter-gatherer peoples in tropical and subtropical latitudes such as the Amazon basin and New Guinea typically have between 10 and 20 different tools, whereas those in the colder northern latitudes of Siberia, Alaska, and Greenland have between 25 and 60 different tools. In addition, peoples in cold northern environments make more complex tools, involving the assembly of components, such as hafting a sharp piece of stone or bone onto the end of a spear and fixing a stone axe head onto a timber shaft. [...]

In very cold environments the problem of storing food for future consumption could be solved for part of the year by building icehouses, which served as freezers for preserving the carcasses. Another solution was to cut the flesh into thin slices and dry them. If this is done properly the pieces will remain edible for a considerable time, but if not they become toxic. Some of the less intelligent, unable to do this properly, would have died from food poisoning. This would have been another of the many selection pressures acting to increase the intelligence of the peoples colonizing the niche of the temperate and cold environments. [...]

The most probable scenario is that the intelligence of North Africans and South Asians increased during both of the two ice ages, the first of which lasted between approximately 70,000 and 50,000 years ago and the second of which lasted between approximately 28,000 and 10,000 years ago.

4. Southeast Asians

... However, their IQ of 87 is fractionally higher than that of the North Africans and South Asians (84), from whom they mostly evolved. The most probable explanation is that there is some East Asian admixture in the Southeast Asians from East Asians who have migrated south and interbred with indigenous populations. There has been substantial migration of East Asians into Southeast Asia.

7. Europeans

... In the last ice age, which lasted from around 28,000 to 10,000 years ago, the winters were significantly colder than those in South Asia with the coldest winter month falling to about -5°C. The terrain in Europe became similar to that of present-day Alaska and Siberia.

... However, despite their high IQ they were not able to develop early civilizations like those built by the South Asians and North Africans because Europe was still cold, was covered with forest, and had heavy soils that were difficult to plough unlike the light soils on which the early civilizations were built, and there were no river flood plains to provide annual highly fertile alluvial deposits from which agricultural surpluses could be obtained to support an urban civilization and an intellectual class (Landes, 1998). [...]

The lower IQs in the range 90 to 94 in Southeast Europe are probably attributable to some gene flow between South Asians and Europeans across the Dardanelles and Aegean, producing a cline of South Asian and European hybrids in the Balkans with IQs intermediate between those of Europeans (99) and South Asians (84).

8. East Asians

... The winters to which they were exposed were much more severe than in South Asia and somewhat more severe than in Europe, with coldest winter temperatures falling to about -12°C during the main Wiirm glaciation. ... It was in response to the cold winters that the East Asians evolved the cold adaptations of the flattened nose to prevent frost bite, the short legs and thick trunk to conserve heat, the subcutaneous layer of fat that gives the skin a yellowish appearance, the sparse facial hair in men (because profuse beards would freeze and produce frost bite), and the epicanthic eye-fold to mitigate the effect of dazzle of reflected light from snow and ice.

9. Arctic Peoples

... The Arctic Peoples did, however, evolve a larger brain size, approximately the same as that of the East Asians, so it is curious that they do not have the same intelligence. A possible explanation for this is that the Arctic Peoples have evolved strong visual memory that would have been needed when they went out on long hunting expeditions and needed to remember landmarks in order to get home in largely featureless environments of snow and ice. An increase of this ability would have required an increase in brain size but is not measured in intelligence tests.