HUMAN EVOLUTION

Vol.13-N. 3-4 - 1998

M.A. Lahr

The Evolution of Modern Human Diversity: A Study of Cranial Variation. Cambridge, UK: Cambridge University Press, 1996. Pp. 416. Martha Lahr is a Brazilian anthropologist who has spent some years at the University of Cambridge working on human cranial variation. She has produced a formidable work of scholarship assembling world data derived from the fossil~recordo. She uses the data to evaluate theories of the evolution and dispersal over the globe of modern humans. She concludes that the evidence supports the single origin theory of modern humans rather than the multiregional theory. The principal weakness of the book is its failure to note the main point of human cranial variation. This is the gradient of brain size with latitude, such that brain size increases with distance from the equator. The existence of this gradient was definitively established a dozen or so years ago by Kenneth Beals and his colleagues (Beals, Smith and Dodd, 1984) and has been confirmed by a number of subsequent studies reviewed by Rushton (1995). Distance from the equator is associated with racial type, because Caucasoids and Mongoloids have evolved at greater distance from the equator than Negroids and hence have evolved larger average brain size. Why this should have occurred is an important theoretical problem for anthropologists to explain. Psychologists have proposed that the explanation for these race differences is that early humans co[onising Eurasia required greater intelligence to deal with the problems of overwintering and this required greater brain size Rushton, 1995; Lynn, 1997). It is time for anthropologists to take up the challenge of this theory. Few are better equipped to do this than Marta Lahr and her colleagues at Cambridge.

References Beals, K.L., Smith, C.L. and Dodd, S.M., 1984. Brain size, cranial morphology, climate and time machines. Current Anthropology, 25, 301-330. Lynn, R., 1997. Geographical variation in Intelligence. In H. Nyborg (Ed) The Scientific Study of Human Nature. New York: Pergamon. Rushton, J.P., 1995. Race Evolution and Behavior. New Brunswick, N.J.: Transaction.

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BOOK REVIEW

Richard Lynn

Dysgenics: Genetic Deterioration in Modern Populations Praeger, 1996, Pp. 237. Richard Lynn's Dysgenetics: genetic deterioration in Modern Populations reaches disturbingconelusions about the current evolution of human intelligence. Professor Lynn, of the, University-'of Ulster in Northern Ireland, assembles studies conducted all over the world and finds~hat.everywhere our genetic potential for intelligence is declining. The only exception is.sub-saharan Africa where contraception isn't used. ~The rate of decline is currently about one IQ point per generation in Europe and North America. Lynn estimates that from 1850 to the present, a total of 5-8 IQ points have been lost. The decline in genotypic intelligence began with the introduction of contraception. In the early 1800s, several books were published which explained various method of preventing pregnancy, and condoms and diaphragms became available. This naturally had a disproportionate influence on the intelligent and well-educated. The rather marked dysgenic trend which developed did not go unnoticed at the time. Charles Darwin expressed deep concern about the effect on civilization of the relawation of natural selection, and he decried the fact that the lowest elements of society had the largest families. It was commonly accepted that members of higher classes were more intelligent, on average, than members of lower classes. Eugenicists took it for granted that in a society with social mobility, such a social class gradient for intelligence would emerge, so they viewed the excessive reproduction of the lower classes with alarm. Many leading thinkers supported eugenics because it seemed to them that if the least-capable people had the most children, the innate quality of the population would durely deteriorate. Francis Galton, Margaret Sanger, H.G. Wells, Julian Huxley, and other idealists saw in eugenics a unique and powerful way to reduce suffering in the world. Eugenicists felt a responsibility to future generations. Currently existing social problems seemed highly resistant to efforts to ameliorate them, but the eugenicists believed that by encouraging bright and healthy couples to have children, and discouraging the dull and diseased from reproducing, it was entirely possible to reduce the incidence of social problems in future generations. In the early decades of the 1900s, eugenics societies were formed in great Britain, the United States, and elsewhere. Eventually,a total of 29 countries passed eugenics legislation of some kind (Saetz, 1984), But after World War II, because of its association with the Nazi's, eugenics was destroyed as a social movement, and the very idea became taboo. If events had unfolded differently - if, for example, Adolph Hitler had never been born eugenics societies would probably have continued to thrive and grow, and today Professor Lynn's book would have been front-page news. Or, more likely, the deterioration in our genetic potential for intelligence would have been detected and reversed long ago. At any rate, the climate of opinion today is such that merely presenting scientific evidence of our genetic deterioration provokes enormous hostility. Thus Professor Lynn's book is a work not only of impressive scholarship, but of considerable courage as well. Lynn's main thesis in Dysgenics is that scientific studies have proven the eugenicists were correct in their concerns about genetic deterioration, and that we have made a grave mistake by rejecting them for non-scientific, non-rational, reasons. Research on twins and adopted children has established the high heritability of intelligence. Studies have Shown that there is, in fact, a social class gradient for intelligence. This means that negative correlations

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between social" class and number of offspring will indeed result in a deterioration of the innate intelligence of the population, just as the eugenicists predicted. Furthermore, socioeconomic status (SES) has been shown to be due in part to genetic factors. Lynn presents several interesting lines of evidence on this point. For example, adopted children whose biological parents were of high SES grow up to be more intelligent than those whose biological parents were of low SES. Brothers in the same family who have higher IQ's than their father tend to move up in SES, whereas those with lower IQ's tend to move down. In T h e Bell Curve, Herrnstein and Murray reported that when the mean IQ in their sample was lowered by just 3 points, all social problems worsened - crime, chronic welfare dependence, illegitimacy, and so on. Conversely, when the mean IQ was raised by the same amount, social problems were alleviated (Herrnstein and Murray, 1994). So it appears the hopes of the eugenicists that they could reduce social problems by increasing innate intelligence were entirely reasonable. It's significant to note that if all mentally retarded people were given sufficient incentives to persuade them to refrain from procreating, mental retardation the major contributing factor to all social problems - would be cut in half in just one generation. Just as in the 1800s, contraception lies at the heart of the problem of dysgenics today. Contraception is now widely available in the West, but unintelligent women have higher failure rates in implementing it. Couples with low IQ's are less likely to use any form of borth control, and among women using the same method, those with low IQ's are much more likely to have accidental pregnancies. Both Iow-lQ women often have many more children than they would ideally like to have because of unplanned, unwanted pregnancies resulting from birth control failure (Van Court, 1984). For this reason, our innate potential for intelligence declines with each new generation. While the decline in genotypic intelligence is the major focus of Dysgenics, professor Lynn also discusses the decline in our genetic potential for health and conscientiousness. Conscientiousness is traditionally known as good character, and it consists of honesty, a strong work ethic, and concern for others. In one study, Lynn found that London criminals had almost twice as many offspring as non-criminals, despite lengthy sojourns in prison. Since there's a significant genetic component to criminality, the high fertility of criminals can be expected to increase the number of criminals in the next generation. This is just one line of evidence presented wich suggests that conscientiousness is declining. Our genetic potential for good health has declined because many diseases which were fatal in the past are now treatable, so the afflicted live long enough to pass on defective genes to their children. The incidence of many of these disorders (such as cystic fibrosis, hemophilia, diabetes, pyloric stenosis, various hart defects, thalassemia, phenylketonuria, and sickle cell anemia) is doubling or tripling each generation. No one would deny treatment to those afflicted, but it's important to realize that ever-greater expenditures will be necessary to care for them unless antenatal diagnosis and therapeutic abortion, or some other eugenic method, makes it possible to reduce their incidence. Professor Lynn's sequel to Dysgenic-to be entitled Eugenics - promises to be even more controversial. In it, he will explicate public policies designed to halt or reverse the genetic deterioration of intelligence, health, and conscientiousness.

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BOOK REVIEW

References Blacker, C.P., 1952. Eugenics Galton and After, London: Duckworth. Herrnstein, Richard, and Charles Murray, 1994. The Bell Curve. New York: Free Press. Saetz, Stephen, 1984. "Eugenics and the Thrid Reich". The Eugenics Bulletin, reprinted on Future Generations website at http://www.ziplink.net/-bright/ Van Court, Marian, 1983. "Unwanted births and dysgenic fertility in the United States". The Eugenics Bulletin, reprinted on Future Generations website at http://www.ziplink.net/-bright/ Van Court, Marian and Frank Bean, 1985. "Intelligence and fertility in the United States: 1912-1982, "Intelligence 9, 23-32.

Corrigendum: Article: Microsatellite evolution in the 5' U T R of the H L A - F gene Human Evolution 13:57-64 Fig,1 - HLA-F microsatellite structure as revealed by sequencing of several primate alleles. 1= short human allele (163 bp); 2 and 3= long human alleles; 4= paternal allele (298); 5= mutated allele (292); 6= paternal allele (286); 7= published sequence (Geraghty, 1990); 8 = langure allele; 9= gorilla allele (the region 11 sequence was not confirmed).