1. Edward Conze, editor, Buddhist Scriptures (Harmondsworth, UK: Penguin, 1959), p. 241.

2. The initial rate of increase of the new mutation in the population is very slow. The thousand-generation estimate, courtesy of the population geneticist James F. Crow, is what it takes to go from gene frequencies of 0.001 (almost nobody) to 0.9 (almost everybody).

3. Sewall Wright, Evolution and the Genetics of Populations: A Treatise in Four Volumes, Volume 4, Variability Within and Among Natural Populations (Chicago: The University of Chicago Press, 1978); Wright, Evolution: Selected Papers, edited by William B. Provine (Chicago: The University of Chicago Press, 1986); Wright, “Surfaces of Selective Value Revisited,” The American Naturalist 131 (January 1988), pp. 115–123; William B. Provine, Sewall Wright and Evolutionary Biology (Chicago: University of Chicago Press, 1986); J. F. Crow, W. R. Engels, and C. Denniston, “Phase Three of Wright’s Shifting-Balance Theory,” Evolution 44 (1990), pp. 233–247. Also, Roger Lewin, “The Uncertain Perils of an Invisible Landscape,” Science 240 (1988), pp. 1405, 1406.

4. Carl Sagan, “Croesus and Cassandra: Policy Responses to Global Change,” American Journal of Physics 58 (1990), pp. 721–730.

5. Plutarch, “Antony,” The Lives of the Noble Grecians and Romans, translated by John Dryden and revised by Arthur Hugh Clough (New York: The Modern Library, 1932), p. 1119.

6. Stewart Henry Perowne, “Cleopatra,” Encyclopaedia Britannica, 15th Edition (1974), Macropaedia, Volume 4, p. 712.

7. Graham Bell, Sex and Death in Protozoa: The History of an Obsession (Cambridge: Cambridge University Press, 1988), pp. 65–66.

8. K. Ralls, J. D. Ballou, and A. Templeton, “Estimates of Lethal Equivalents and Cost of Inbreeding in Mammals,” Conservation Biology 2 (1988), pp. 185–193; P. H. Harvey and A. F. Read, “Copulation Genetics: When Incest Is Not Best,” Nature 336 (1988), pp. 514–515.

9. James L. Gould and Carol Grant Gould, Sexual Selection (New York: W. H. Freeman, 1989), p. 64.

10. Anne E. Pusey and Craig Packer, “Dispersal and Philopatry,” Chapter 21 of Barbara B. Smuts, Dorothy L. Cheney, Robert M. Seyfarth, Richard W. Wrangham, and Thomas T. Struhsaker, editors, Primate Societies (Chicago: University of Chicago Press, 1986), p. 263.

11. P. H. Harvey and K. Ralls, “Do Animals Avoid Incest?” Nature 320 (1986), pp. 575, 576; D. Charlesworth and B. Charlesworth, “Inbreeding Depression and Its Evolutionary Consequences,” Annual Review of Ecology and Systematics 18 (1987), pp. 237–268. The latter reference contains a good summary of the means by which the incest taboo is enforced in plants.

12. John Paul Scott and John L. Fuller, Genetics and the Social Behavior of the Dog (Chicago: University of Chicago Press, 1965), pp. 406, 407.

13. William J. Schull and James V. Neel, The Effects of Inbreeding on Japanese Children (New York: Harper and Row, 1965).

14. Morton S. Adams and James V. Neel, “Children of Incest,” Pediatrics 40 (1967), pp. 55–62.

15. Theodosius Dobzhansky was a leading twentieth-century geneticist. He gives this example in his Mankind Evolving (New Haven: Yale University Press, 1962), p. 281.

16. Over long enough intervals, isolation—even in large populations—generates diversity. When, for example, the Pangaea supercontinent broke up, the populations on adjacent land masses were no longer able (or at least not much able) to interbreed, and gene combinations established on one continent would by no means automatically be transferred to another; no longer did outbreeding link up the gene pools of widely separated populations. The unique biology of such isolated regions as Australia, New Zealand, Madagascar, or the Galapagos Islands is due to tectonic or other kinds of geographical isolation.

17. George Gaylord Simpson, Tempo and Mode in Evolution (New York: Columbia University Press, 1944), p. 119.

18. We recognize with Wright that we are close to postulating group selection here. But any argument for optimum gene frequencies in a population must, it seems to us, do so.

19. John Tyler Bonner, The Evolution of Culture in Animals (Princeton, NJ: Princeton University Press, 1980): “We can see the seeds, the origins, of everything we know about our culture in the distant past. This means that every aspect of our culture can benefit from some understanding of the biology from which it sprang” (p. 186).