Africans have slower reaction times. Professor Richard Lynn gives evidence for this in his recently published book Race Differences in IQ.

Publication date: 6 February, 2006

Richard Lynn. Race Differences in Intelligence: An Evolutionary Analysis (2006).
Atlanta, Georgia: Washington Summit Books (PO Box 3514, Augusta, GA 30914) ISBN 1-59368-020-1 pp. 318., US$37.95 (HB), $20.95 (PB) (add $6 for overseas orders). 

A review by Prof.J.P.Rushton to be published in March in Personality and Individual Differences describes the book and is given below.

Lynn?s book represents the culmination of more than a quarter of a century?s work on race differences in intelligence. It was in 1977 that he first ventured into this field ? some would say minefield ? with the publication of two papers on the IQ in Japan and Singapore. Both showed that the East Asians obtained higher means than white Europeans in the United States and Britain. These initial studies were criticised, but the present book lists 60 studies of the IQs of indigenous East Asians all of which confirm the original claim. 
  Hitherto studies of race differences in intelligence have been largely conducted and discussed in local contexts. In the United Sates they have been largely concerned with the IQs of whites, blacks, Hispanics, 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. These differences have typically been explained by racism and discrimination of Europeans against minorities the legacy of slavery, although a number of writers have posited a significant genetic factor (Jensen, 1998; Rushton and Jensen, 2005). Lynn?s book differs in taking a global perspective and consists of a review more than 500 studies published world wide from the beginning of the twentieth century up to the present. He devotes a chapter to each of ten races, differentiated by Cavalli-Sforza, Menozzi and Piazza (1994) into ?genetic clusters?, which he regards as a transparent euphemism for races.
  His conclusions are that the East Asians (Chinese, Japanese and Koreans) have the highest mean IQ at 105. These are followed by the Europeans (IQ 100). Some way below these are the Inuit (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 least intelligent races 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 each of the ten races there follows a chapter on the reliability and validity of the measures. These show that the studies have high reliability in the sense that different studies of racial IQs give closely similar results. For instance, East Asians invariably obtain high IQs, not only in their own native homelands but in Singapore, Malaysia, Hawaii and North America. To establish the validity of the racial IQs he shows that they have high correlations with performance in the international studies of achievement in mathematics and science. Racial IQs also have high correlations with national economic development, providing a major contribution to the problem of why the peoples of some nations are rich and others poor. He argues further that the IQ differences between the races explain the differences in achievement in making the Neolithic transition from hunter-gathering to settled agriculture, the building of early civilizations, and the development of mature civilizations during the last two thousand years.

Lynn tackles the problem of the environmental and genetic determinants of race differences in intelligence and concludes that these contribute about equally to the phenotypic differences. He argues that the consistency of racial IQs in many different locations can only be explained by powerful genetic factors. He works out the genetic contribution in most detail for the sub-Saharan Africans. His argument is that sub-Saharan Africans in the United States experience the same environment as whites, as regards determinants of intelligence. He argues that they have as good nutrition as whites, as shown by their having the same average height in studies going back to World War 1, and they have approximately the same education as whites. He presents evidence that blacks in the southern states have very little white ancestry and have an IQ of about 80, and that proposes that this can be adopted as the genotypic IQ of blacks, i.e. the IQ that blacks attain when they are reared in the same environment as whites. The IQ of blacks in sub-Saharan Africa is a good deal lower at 67. Hence, the adverse environment in sub-Saharan Africa, which he regards as consisting principally of poor nutrition and health, contributes about 13 IQ points to the low IQ in sub-Saharan Africa. Lynn?s estimate is not too different from that advanced in 1969 by Jensen to the effect that about two thirds of the low IQ of blacks in the United States is attributable to genetic factors, and the more recent estimate of Rushton and Jensen (2005) that the figure is around 80 percent. Lynn has (unsurprisingly for those familiar with his work) put a bit more weight on the genetic factor.
  The last three chapters are concerned with the book?s subtitle (An Evolutionary Analysis) and discusses how race differences in intelligence have evolved. He begins by putting the problem in context by summarizing Jerison?s (1973) classic study showing that during the course of evolution species have evolved greater intelligence in order to survive in more cognitively demanding environments. For instance, in one of the most dramatic of these developments, early mammals evolved larger brains and greater intelligence to survive in the nocturnal environment, for which they needed to evolve larger auditory and olfactory analysing centres in the brain.
  The same principle, Lynn argues, explains the evolution of race differences in intelligence in humans. He elaborates the argument he has advanced over the last fifteen years that the race differences in intelligence have evolved as adaptations to colder environments as early humans migrated out of Africa. In North Africa and South Asia, and even more in Europe and Northeast Asia, these early humans encountered the problems of having to survive during cold winters when there were no plant foods and they had to hunt big game to survive. They also had to solve the problems of keeping warm. These required greater intelligence than was needed in tropical and semi-tropical equatorial Africa where plant foods are plentiful throughout the year. He shows that race differences in brain size and intelligence are both closely associated with low winter temperatures in the regions they inhabit. For instance, he gives a figure of 1282 cc for the average brain size of sub-Saharan Africans, as compared with 1367 cc for Europeans and 1416 cc for Orientals. His analysis relating race differences in intelligence to exposure to low winter temperatures has recently been independently corroborated by Templer and Arikawa (2005). 
  From time to time Lynn notes anomalies in his theory that require explanations. One of these is that the Europeans have made most of the great intellectual advances and discoveries, while the East Asians, despite having a higher IQ have made relatively few (as extensively documented by Murray, 2003). Lynn proposes the explanation for this may be that the East Asians are more conformist that Europeans and this inhibits creative achievement. He also notes one or two anomalies in his cold winter theory of race differences in intelligence. The most striking of these is that the Inuit have been exposed to the coldest winter temperatures and have evolved large brains, the same average size as that of the East Asians. Yet their IQ is only 91, and this is the IQ obtained by those who attend the same schools as Europeans. To explain this anomaly he proposed that two genetic processes must be assumed to explain the evolution of race differences in intelligence. The first of these is that differences in the frequencies of the alleles for high and low intelligence have evolved between races such that the alleles for high intelligence are more common in the races with the higher IQs and less common in the races with the lower IQs. 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.

He now suggests that there must have been a second genetical process that several new alleles for high intelligence must have appeared as mutations in some races but did not appear in others, and once these had appeared they were never transmitted to other races. These new mutant alleles for high intelligence would have been most likely to appear in large populations because a mutation is a chance genetic event and hence would have been more likely to occur in races with large populations than in those with small. The Inuit comprised only very small populations numbering today around 55,000, so they would be unlikely have had mutations for higher intelligence that have to be assumed in the East Asians and Europeans. Once a new mutant allele for higher intelligence had appeared in the East Asians and Europeans it would have conferred 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. From time to time matings would take place between demes and by this means new mutant alleles for higher intelligence would spread from one deme to another and eventually throughout an entire race.
  However, this would take some considerable time, and Lynn proposes that in 25,000 years, consisting of approximately 1,000 generations, an advantageous allele would be transmitted about 800 miles. Hence, an advantageous allele occurring as a mutant in the region of, say, Beijing, 25,000 years ago would not yet have spread outside China and would take another 50,000 years or so to reach the Inuit peoples of far North East Asia and even longer to cross the Bering Straits into Alaska. In addition, there are geographical barriers of high mountains between the East Asians and the Inuit that would have imposed a further impediment for the new alleles for higher intelligence being transmitted from East Asia northwards. He extends this explanation to the low IQs of the Australian Aborigines and Bushmen. These have only been small populations, so the chance of mutations of high IQ alleles in them would have been low.
  To the arguments presented by Jensen (1998) for a substantial genetic determination of the difference in intelligence between blacks and whites in the United States, Lynn adds a more general one. He advances the general principle of evolutionary biology that wherever subspecies, strains or races have evolved in different environments they invariably develop differences in all characteristics for which there is genetic variation as a result of mutations occurring in some subspecies and of adaptations to different environments, and asserts that intelligence cannot be an exception. He concludes witheringly that
?The position of environmentalists that over the course of some 100,000 years peoples separated by geographical barriers in different parts of the world evolved into ten different races with pronounced genetic differences in morphology, blood groups and the incidence of genetic diseases, and yet have identical genotypes for intelligence, is so improbable that those who advance it must either be totally ignorant of the basic principles of evolutionary biology or else have a political agenda to deny the importance of race. Or both ?. So much for the assertion of the American Psychological Association?s task force under the chairmanship of Ulrich Neisser set up to produce a consensus statement on what is known about intelligence that concluded that there is no persuasive evidence for genetic race differences (Neisser et al., 1998). With the publication of Lynn?s book it will never again be possible to make this assertion and retain any credibility.
  Over the years Lynn has made a number of important contributions to the field of intelligence. He has written the standard works on the dysgenic processes that have been taking place almost worldwide for the last century and on how these could be addressed (Lynn, 1996, 2001). He has shown that the problem of why some nations are rich and others poor is largely explained by the intelligence of the populations (Lynn and Vanhanen, 2002). He has overturned the century long consensus that there is no sex difference in intelligence by showing that men have a higher average IQ than women by approximately 5 IQ points (Lynn and Irwing, 2004). But I would guess that the present book documenting global race differences in intelligence and analysing how these have evolved will come to be seen as his crowning achievement. 

  References

Cavalli-Sforza, L.L., Menozzi, P. and Piazza, A. (1994) The History and Geography of Human Genes.  Princeton, NJ: Princeton University Press.
Jensen, A .R. (1998) The g Factor. Westport,CT: Praeger.
Jerison, H. (1973) Evolution of the brain and intelligence. New York: Academic Press.

Lynn, R. (1996)  Dysgenics: Genetic Deterioration in Modern Populations
Westport,CT: Praeger.
Lynn, R. (2001) Eugenics: A Reassessment. Westport, CT: Praeger.
Lynn, R. and Irwing, P. (2004) Sex differences on the Progressive Matrices: a meta-analysis. Intelligence, 32, 481-498.

Lynn, R. and Vanhanen, T. (2002) IQ and the Wealth of Nations. Westport, CT: Praeger.

Murray, C. (2003) Human Accomplishment. New York: Harper Collins.
Neisser, U.et al. (1996) Intelligence: knowns and unknowns. American Psychologist, 51, 77-101.

Rushton, J. P. and Jensen, A. R. (2004) Thirty years of research on race differences in cognitive ability. Psychology, Public Policy and Law, 11, 235-294. 

Templer, D.I. and Arikawa, H. (2005) Temperature, shin color, per capita income and IQ: an international perspective. Intelligence, (to appear)

Biography

Richard Lynn was born in 1930. He graduated in Psychology and took his Ph.D. at the University of Cambridge. He has been lecturer in Psychology at the University of Exeter, professor of Psychology at the Economic and Social Research Institute, Dublin, and professor and head of the department of Psychology at the University of Ulster; now professor emeritus. His main work has been on intelligence and personality. His books include Personality and National Character (1972),Dimensions of Personality (1980), Educational Achievement in Japan (1988), Dysgenics: Genetic Deterioration in Modern Populations (1996), Eugenics: A Reassessment (2001) and (jointly with Tatu Vanhanen) IQ and the Wealth of Nations (2002). Awards he has received include the Passingham Prize (Cambridge University Prize for the best Psychology student of the year) and the US Mensa Awards for Excellence 1985 and 1993 for work on intelligence.  See his website for more details.