1. Such possibilities certainly were not lost on Charles Darwin, who in 1872 published The Expression of the Emotions in Man and Animals (reprinted by the University of Chicago Press, 1965), a book that attempted to extend principles developed in On the Origin of Species to the fields of human ethology and psychology.
2. See R. C. Lewontin, S. Rose, and L. J. Kamin, Not in Our Genes (New York: Pantheon Books, 1984).
3. L. S. Hearnshaw, Cyril Burt: Psychologist (London: Hodder and Stoughton, 1979). The Burt episode and its place within the broader debate over genetics and human IQ also are reviewed in Lewontin, Rose, and Kamin, Not in Our Genes, and in S. J. Gould, The Mismeasure of Man (New York: Norton, 1981).
4. Between 1907 and 1917, sixteen American states passed sterilization laws directed against the mentally retarded. Constitutionality of these laws was upheld in a Supreme Court ruling in which Justice Oliver Wendell Holmes declared that "three generations of imbeciles are enough."
5. These were psychologist Robert Joynson and sociobiologist Ronald Fletcher, and their side of the story is recounted in another recent book on human intelligence and IQ: R. J. Herrnstein and C. Murray, The Bell Curve (New York: Simon & Schuster, 1994).
6. Such thoughts have been agonizing to me in composing this book. The subculture in which I have been trained accepts science as a means to understanding life. Prolonged exposure instead to Hinduism, Freudism, Marxism, or astrologism, would have given me quite different views. For a philosophical critique of the "legend" of science as an unerring approach to truth, see P. Kitcher, The Advancement of Science (New York: Oxford University Press, 1993).
7. In The Mismeasure of Man, S. J. Gould details the history of IQ research in the context of hereditarian theories.
8. Not all would agree with this statement. A fundamental empirical point emphasized in Herrnstein and Murray's The Bell Curve is that intelligence is real, objective, and repeatably measurable by any of a battery of cognitive tests that all tend to converge on the same assessment and that also correlate well with common-sense perceptions of mental ability.
9. T. J. Bouchard, D. T. Lykken, M. McGue, N. L. Segal, and A. Tellegen, "Sources of Human Psychological Differences: The Minnesota Study of Twins Reared Apart," Science 250 (1990): 223-228.
10. The "broad-sense" heritability of a trait is defined as the proportion of the trait's total phenotypic variance within a population that is accounted for by genetic differences:
H = genetic variance / (genetic variance + environmental variance).
Because genetic and environmental variances are population-specific rather than universal properties, heritabilities for a trait can differ considerably from one setting to another as a result of differences in genetic variance, environmental variance, or both. Another caveat about particular heritability estimates reported in the literature is that they can vary according to the genetic model to which empirical data are fit. Some models, for example, assume additive allelic contributions by an unspecified number of genes (heritability in the "narrow sense"), whereas others may include nonadditive effects between alleles of a locus (dominance) or between alleles of different genes (epistasis). Furthermore, when extensive epistasis (gene interaction) is involved, twin studies may uncover evidence for strong genetic impact on variation in a trait, whereas parent-offspring or other sibship studies might suggest relatively low heritabilities for the same trait. Such discrepancies emphasize how genetic influences sometimes can be both substantial and nonfamilial.
11. D. Lykken and A. Tellegen, "Happiness is a Stochastic Phenomenon," Psychological Sci. 7 (1996): 186-189. In contrast to the large genetic influence on happiness or well-being, the authors report that none of the following could account for more than about 3 percent of the interperson variance in general sense of contentment: socioeconomic status, educational attainment, family income, marital status, or degree of religious commitment. Although each person's happiness fluctuates in response to life's contingencies, these transitory oscillations appear to center around a stable temperamental "set point" characteristic of each individual. See also D. G. Myers and E. Diener, "Who Is Happy?" Psychological Sci. 6 (1995): 10-19.
12. A. Tellegen et al., "Personality Similarity in Twins Reared Apart and Together," J. Personality and Social Psychol. 54 (1988): 1031-1039.
13. J. C. Loehlin and R. C. Nichols, Heredity, Environment, and Personality: A Study of 850 Sets of Twins (Austin, Tx.: University of Texas Press, 1976); J. P. Rushton, D. W. Fulker, M. C. Neale, D. K. B. Nias, and H. J. Eysenck, "Altruism and Aggression: The Heritability of Individual Differences," J. Personality and Social Psychol. 6 (1986): 1192-1198; N. G. Martin, L. J. Eaves, A. C. Heath, R. Jardine, L. M. Feingold, and H. J. Eysenck, "Transmission of Social Attitudes," Proc. Natl.
Acad. Sci. USA 83 (1986): 4364-4368; L. J. Eaves, H. J. Eyysenck, and N. G. Martin, Genes, Culture and Personality: An Empirical Approach (New York: Academic Press, 1989). A particularly intriguing twin study concluded that genetic factors account for about 60 percent of the variance in cognitive ability among the elderly [G. E. McClearn, B. Johansson, S. Berg, N. L. Pederson, F. Ahern, S. A. Petrill, and R. Plomin, "Substantial Genetic Influence on Cognitive Abilities in Twins 80 or More Years Old," Science 276 (1997): 1560-1563].
14. A quote attributed to Douglas Copeland in a recent Rolling Stone magazine.
15. Typical examples of numerous papers on this topic include V. S. Johnston and M. Franklin, "Is Beauty in the Eye of the Beholder?" Ethology and Sociobiol. 14 (1993): 183-199; S. W. Gangestad, R. Thornhill, and R. A. Yeo, "Facial Attractiveness, Developmental Stability, and Fluctuating Asymmetry," Ethology and Sociobiol. 15 (1994): 73-85. Several reviews also have appeared in scientific and popular outlets: J. Horgan, "The New Social Darwinists," Sci. Amer. 273 (1995): 174-181; G. Cowley, "The Biology of Beauty," Newsweek, 3 June 1996.
16. N. G. B. Jones and E. da Costa, "A Suggested Adaptive Value of Toddler Night Waking: Delaying the Birth of the Next Sibling," Ethology and Sociobiol. 8 (1987): 135-142; J. Shepher and J. Reisman, "Pornography: A Sociobiological Attempt at Understanding," Ethology and Sociobiol. 6 (1985): 103-114; J. W. Burgess, "Do Humans Show a 'Species-Typical' Group Size?" Ethology and Sociobiol. 5 (1984): 51-57; J. W. Burgess, "The Social Biology of Human Populations: Spontaneous Group Formation Conforms to Evolutionary Predictions of Adaptive Aggregation Patterns," Ethology and Sociobiol. 10 (1989): 343-359.
17. M. W. Weiderman and E. R. Allgeier, "Gender Differences in Sexual Jealousy: Adaptationist or Social Learning Explanation?" Ethology and Sociobiol. 14 (1993): 115-140; L. Paul and L. R. Hirsch, "Human Male Mating Strategies: 2. Moral Codes of 'Quality and Quantity' Strategists," Ethology and Sociobiol. 17 (1996): 71-86; K. B. Kerber, "The Marital Balance of Power and quid pro quo: An Evolutionary Perspective," Ethology and Sociobiol. 15 (1994): 283-297; D. Thiessen, R. K. Young, and R. Burroughs, "Lonely Hearts Advertisements Reflect Sexually Dimorphic Mating Strategies," Ethology and Sociobiol. 14 (1993): 209-229.
18. D. Daniels, "The Evolution of Concealed Ovulation and Self-Deception," Ethology and Sociobiol. 4 (1983): 69-87; P. W. Turke, "Effects of Ovulatory Concealment and Synchrony on Protohominid Mating Systems and Parental Roles," Ethology and Sociobiol. 5 (1984): 33-44. For a more cautionary view, see also H. D. Steklis and C. H. Whiteman, "Loss of Estrus in Human Evolution: Too Many Answers, Too Few Questions," Ethology and Sociobiol. 10 (1989): 417-434; I. Schroder, "Concealed Ovulation and Clandestine Copulation: A Female Contribution to Human Evolution," Ethology and Sociobiol. 14 (1993): 381-389.
19. R. M. Nesse and G. C. Williams, Why We Get Sick (New York: Random House, 1994).
20. M. Eals and I. Silverman, "The Hunter-Gatherer Theory of Spatial Sex
Differences: Proximate Factors Mediating the Female Advantage in Recall of Object Arrays," Ethology and Sociobiol. 15 (1994): 95-105.
21. W. D. Hamilton, "The Genetical Evolution of Social Behavior, 1, 2," J. Theoretical Biology 7 (1964): 1-15, 17-52; R. L. Trivers, "Parent-Offspring Conflict," Amer. Zool. 14 (1974): 249-264. For a recent review, see H. C. J. Godfray, "Evolutionary Theory of Parent-Offspring Conflict," Nature 376 (1995): 133-138.
22. A. Zahavi, "Reliability in Communication Systems and the Evolution of Altruism," in B. Stonehouse and C. Perrins, eds., Evolutionary Ecology (Baltimore, Md.: University Park Press, 1977), pp. 253-259.
23. D. Haig, "Genetic Conflicts in Human Pregnancy," Quarterly Rev. Biol. 68 (1993): 495-532.
24. For a recent example, see A. M. Warnecke, R. D. Masters, and G. Kempter, "The Roots of Nationalism: Nonverbal Behavior and Xenophobia," Ethology and Sociobiol. 13 (1992): 267-282. See also B. J. Craige, American Patriotism in a Global Society (Albany: State University of New York Press, 1996). One thesis of this book is that in the modern world, human predilections for tribalism promote nationalism, which in turn leads to a political dualism wherein love of country is linked to hatred of others. Another thesis is that such dualism is increasingly inappropriate in a global society.
25. From Darwin's (1871) The Descent of Man, as quoted in Craige, American Patriotism.
26. According to "Hamilton's rule" (Hamilton, "Genetical Evolution of Social Behavior"), a behavior is favored by selection whenever Awx + SryxAwy > 0, where Awx is the change the behavior causes in the individual's fitness, Awy is the change the behavior causes in the relative's fitness, and r-yx is the genetic relatedness of the individuals (e.g., r = 0.5 for full-sibs, r = 0.25 for half-sibs, and r = 0.125 for first cousins).
27. Another sociobiological possibility is that homosexuality in human ancestors served to minimize intragroup conflict and promote social harmony. In one of human's closest evolutionary relatives, the bonobo or pygmy chimpanzee (Pan paniscus), same-sex trysts are extremely common and serve to resolve power issues peacefully. See F. de Waal, Bonobo: The Forgotten Ape (Berkeley: University of California Press, 1997). On the other hand, if gay and lesbian lifestyles in humans were unknown to science, sociobiologists could glibly explain their absence as an expected consequence of the diminution in personal reproductive fitness.
28. E. O. Wilson, On Human Nature (Cambridge, Mass.: Harvard University Press, 1978).
29. R. Thornhill and N. W. Thornhill, "Human Rape: An Evolutionary Analysis," Ethology and Sociobiol. 4 (1983): 137-173.
30. This possibility has been considered in the sociobiological literature, and one interpretation is that inbreeding is regulated societally not to avoid production of genetically defective children in extremely close matings, but instead to discourage more distant (e.g., cousin) matings that would serve to concentrate wealth and power within families, and thereby threaten the established rulers and lawmakers of society. See N. W. Thornhill, "The Evolutionary Significance of Incest Rules," Ethology and Sociobiol. 11 (1990): 113-129. For further discussion, see also C. V. J. Welham, "Incest, an Evolutionary Model," Ethology and Sociobiol. 11 (1990): 97-111.
31. M. B. Mulder, "Human Behavioral Ecology," in J. R. Krebs and N. B. Davies, eds., Behavioral Ecology, 3rd ed. (London: Blackwell, 1991), pp. 69-98.
32. Many books illustrate the extensive speculation that often accompanies scenarios about the selective agents in human evolution, but a fine recent example is K. Glantz and J. Pearce, Exiles from Eden: Psychotherapy from an Evolutionary Perspective (New York: Norton, 1989). Such "Pleistocentric" treatments often tend to view modern humans as genetically out of step with the modern world, or as "stone-agers in the fast lane."
33. D. S. Wilson, "Adaptive Genetic Variation and Human Evolutionary Psychology," Ethology and Sociobiol. 15 (1994): 219-235.
34. For general information, see E. O. Wilson, Sociobiology, The New Synthesis (Cambridge, Mass.: Harvard University Press, 1975). For descriptions of eusocial ants and wasps, see E. O. Wilson, The Insect Societies (Cambridge, Mass.: Harvard University Press, 1971). Eusociality refers to a suite of behaviors displayed by certain colony-living species, including cooperation in the care of young and reproductive divisions of labor with more or less sterile individuals working on behalf of the reproductives. For descriptions of matriphagy in spiders, see T. A. Evans, E. J. Wallis, and M. A. Elgar, "Making a Meal of Mom," Nature 376 (1995): 299. For more information on parthenogenesis, see R. M. Dawley and J. P. Bogart, eds., Evolution and Ecology of Unisexual Vertebrates (Albany: New York State Museum, 1989). Parthenogenesis or virgin birth is the development of an individual from a female gamete without the involvement of sperm.
35. C. J. Lumsden and E. O. Wilson, Genes, Mind, and Culture (Cambridge, Mass.: Harvard University Press, 1981); R. Dawkins, The Selfish Gene (New York: Oxford University Press, 1976).
36. A relatively new branch of mathematical population genetics attempts to describe quantitatively the theory of gene-culture coevolution. See M. W. Feldman and K. N. Laland, "Gene-Culture Coevolutionary Theory," Trends Ecol. Evol. 11 (1996): 453-457. In formal gene-culture models, individuals are described in terms of their "phenogenotype," the genotypic and phenotypic aspects of which are specified according to rules of Mendelian heredity and cultural transmission, respectively. Lactose absorption provides a straightforward example of a feature influenced by gene-culture coevolution. Individual humans are either lactose absorbers or malabsorbers, with absorption probably inherited as an autosomal dominant trait.
Human societies with long as opposed to short traditions of dairy farming tend to show much higher frequencies of lactose-absorption alleles. Formal gene-culture coevolutionary models attempt to account for such observations by examining the dynamics of allelic frequency change under various selection regimes, competing assumptions about the genetic bases of lactose absorption, and alternative modes of cultural transmission of milk usage.
37. For an introduction to this perspective, see papers in J. H. Barkow, L. Cos-mides, and J. Tooby, eds., The Adapted Mind: Evolutionary Psychology and the Generation of Culture (New York: Oxford University Press, 1992).
38. Nesse and Williams, Why We Get Sick, provide an overview, and the following gives an example of a more specific hypothesis: J. R. Feierman, "A Testable Hypothesis about Schizophrenia Generated by Evolutionary Theory," Ethology and Sociobiol. 15 (1994): 263-282.
39. G. F. Eden, J. W. VanMeter, J. M. Rumsey, J. M. Maisog, R. P. Woods, and T. A. Zeffiro, "Abnormal Processing of Visual Motion in Dyslexia Revealed by Functional Brain Imaging," Nature 382 (1996): 66-69; C. Frith and U. Frith, "A Biological Marker for Dyslexia," Nature 382 (1996): 19-20.
40. "Reductionists Lay Claim to the Mind," Nature 381 (1996): 97.
41. S. Rose, "The Rise of Neurogenetic Determinism," Nature 373 (1995): 380-382.
42. S. Baron-Cohen, Mindblindness: An Essay on Autism and Theory of Mind (Cambridge, Mass.: MIT Press, 1995).
43. O. Sacks, An Anthropologist on Mars: Seven Paradoxical Tales (New York: Knopf, 1995). Oliver Sacks relates the remarkable story of an autistic child, Temple Grandin, who grew up to teach agricultural science at Colorado State University. Through amazing exercises of will, Grandin learned life's survival skills, yet she remains unable to appreciate concepts such as romantic love or empathy, or to develop meaningful emotional connections to others.
44. J. B. Martin, "Molecular Genetics of Neurological Diseases," Science 262 (1993): 674-676.
45. L. L. Hall, ed., Genetics and Mental Illness (New York: Plenum, 1996).
46. R. P. Ebstein et al., "Dopamine D4 Receptor (D4DR) Exon III Polymorphism Associated with the Human Personality Trait of Novelty Seeking," Nature Genetics 12 (1996): 78-80; J. Benjamin, B. Greenberg, D. L. Murphy, L. Lin, C. Patterson, and D. H. Hamer, "Population and Familial Association Between the D4 Dopamine Receptor Gene and Measures of Novelty Seeking," Nature Genetics 12 (1996): 81-84.
47. K.-P. Lesch et al., "Association of Anxiety-Related Traits with a Polymorphism in the Serotonin Transporter Gene Regulatory Region," Science 274 (1996): 1527-1531.
48. F. E. Bloom and D. J. Kupfer, eds., Psychopharmacology: The Fourth Generation of Progress (New York: Raven Press, 1995).
49. D. Johnson, "Can Psychology Ever Be the Same Again after the Genome is Mapped?" Psychological Sci. 1 (1990): 331-332.
50. F. Crick, An Astonishing Hypothesis: The Scientific Search for the Soul (New York: Scribner, 1994).
51. N. G. Waller, B. A. Kojetin, T. J. Bouchard, Jr., D. T. Lykken, and A. Tellegen, "Genetic and Environmental Influences on Religious Interests, Attitudes, and Values: A Study of Twins Reared Apart and Together," Psychological Sci. 1 (1990): 138-142.
52. Another conceivable form of personal empowerment through religion has been suggested by Herbert Benson in Timeless Healing: The Power and Biology of Belief (New York: Simon & Schuster, 1996), who claims that a powerful belief in a god manifests itself in placebo effects that improve an individual's bodily health. For critical reviews of this scientifically controversial perspective, see I. Tessman and J. Tessman, "Mind and Body," Science 276 (1997): 369-370; W. Roush, "Herbert Benson: Mind-Body Maverick Pushes the Envelope," Science 276 (1997): 357-359.
53. The thesis that the origins of human morality lie in biology is far from new, having been discussed by numerous writers. For a history and compilation of such thought, see R. D. Alexander, The Biology of Moral Systems (New York: Aldine De Gruyter, 1987). Not all biologists agree, however. For example, the prominent evolutionary biologist and Christian ideologist David Lack maintained that morality was of divine source: e.g., D. L. Lack, Evolutionary Theory and Christian Belief; The Unresolved Conflict (London: Methuen, 1957).
54. F. de Waal, Good Natured: The Origins of Right and Wrong in Humans and Other Animals (Cambridge, Mass.: Harvard University Press, 1996).
55. F. J. Ayala, "The Myth of Ethical Genes," Trends Ecol. Evol. 10 (1995): 470-471.
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Autism is a developmental disorder that manifests itself in early childhood and affects the functioning of the brain, primarily in the areas of social interaction and communication. Children with autism look like other children but do not play or behave like other children. They must struggle daily to cope and connect with the world around them.