1. Quoted in Gavin Rylands de Beer, editor, “Darwin’s Notebooks on Transmutation of Species, Part IV: Fourth Notebook (October 1838–10 July 1839),” Bulletin of the British Museum (Natural History), Historical Series (London) 2 (5) (1960), pp. 151–183; quotation (from notebook entry 47) appears on p. 163.

2. Frank Roper, The Missing Link: Consul the Remarkable Chimpanzee (Manchester: Abel Heywood, 1904). A now-extinct primate of some 30 million years ago, perhaps ancestral to both apes and humans, has been named Proconsul, in honor of the Victorian sophisticate.

3. Mortimer J. Adler, The Difference of Man and the Difference It Makes (New York: Holt, Rinehart and Winston, 1967), p. 84.

4. Theodosius Dobzhansky, Mankind Evolving (New Haven: Yale University Press, 1962), p. 339.

5. George Gaylord Simpson, The Meaning of Evolution (New Haven: Yale University Press, 1949), p. 284.

6. Adler, op. cit., p. 136.

7. This answer was first proposed in a lecture to the Yale Divinity School in 1880 by Darwin’s friend, the botanist and evolutionary biologist Asa Gray (Natural Science and Religion [New York: Scribner’s, 1880]).

8. Metaphysics, Materialism and the Evolution of Mind: Early Writings of Charles Darwin, transcribed and annotated by Paul H. Barrett, commentary by Howard E. Gruber (Chicago: University of Chicago Press, 1974), p. 187.

9. Especially in The Descent of Man.

10. Adam Smith, An Inquiry into the Nature and Causes of the Wealth of Nations, Edwin Cannan, editor (New York: Modern Library/Random House, 1937), Chapter II, “Of the Principle Which Gives Occasion to the Division of Labour,” p. 13.

11. Keith Thomas, Man and the Natural World: A History of the Modern Sensibility (New York: Pantheon, 1983), p. 31.

12. Frans de Waal, Peacemaking Among Primates (Cambridge, MA: Harvard University Press, 1989), p. 82.

13. Smith, op. cit., p. 14.

14. Tacitus, The Histories, translated by Alfred John Church and William Jackson Brodribb, in Volume 15 of Great Books of the Western World, Robert Maynard Hutchins, editor in chief (Chicago: William Benton/Encyclopaedia Britannica, 1952, 1977), Book IV, 13, 17, pp. 269, 271.

15. Another purported distinction of humans based solely on bodily form: “Man is, I believe the only animal that has a marked projection in the middle of the face,” an opinion of the eighteenth-century aesthete Uvedale Price. (Quoted in Keith Thomas, op. cit., p. 32.) He may have been ignorant of tapirs and proboscis monkeys, but elephants?

16. Thomas Aquinas, Summa Theologica, Volume I, translated by Fathers of the English Dominican Province, revised by Daniel J. Sullivan, Volume 19 of Great Books of the Western World (Chicago: Encyclopaedia Britannica, 1952), Second Part, Part I, I. “Treatise on the Last End,” Question I, “On Man’s Last End” (p. 610); Part I, II. “Treatise on Human Acts,” Question XIII, “Of Choice” (pp. 673, 674); and Question XVII, “Of the Acts Commanded by the Will” (p. 688).

17. Jakob von Uexküll, “A Stroll Through the Worlds of Animals and Men: A Picture Book of Invisible Worlds” (1934), Part I of Claire H. Schiller, translator and editor, Instinctive Behavior: The Development of a Modern Concept (New York: International Universities Press, 1957), p. 42.

18. John Dewey, Reconstruction in Philosophy (New York: Henry Holt, 1920), p. 1.

19. Hugh Morris, The Art of Kissing (1946), forty-seven pages, no publisher is given in this demure little pamphlet.

20. Desmond Morris, The Naked Ape (New York: Dell, 1984) (originally published in 1967 by McGraw Hill; revised edition published in 1983), p. 62.

21. Donald Symons, The Evolution of Human Sexuality (New York: Oxford University Press, 1979), pp. 78, 79.

22. Gerritt S. Miller, “Some Elements of Sexual Behavior in Primates, and Their Possible Influence on the Beginnings of Human Social Development,” Journal of Mammalogy 9 (1928), pp. 273–293.

23. Gordon D. Jensen, “Human Sexual Behavior in Primate Perspective,” Chapter 2 in Joseph Zubin and John Money, editors, Contemporary Sexual Behavior: Critical Issues in the 1970s (Baltimore: The Johns Hopkins University Press, 1973), p. 20.

24. Cf. ibid., p. 22.

25. For example, K. Imanishi, “The Origin of the Human Family: A Primatological Approach,” Japanese Journal of Ethnology 25 (1961), pp. 110–130 (in Japanese); discussed in Toshisada Nishida, editor, The Chimpanzees of the Mahale Mountains: Sexual and Life History Strategies (Tokyo: University of Tokyo Press, 1990), p. 10.

26. By the philosopher Johan Huizinga, Homo Ludens (Boston: Beacon, 1955).

27. Epictetus, The Discourses of Epictetus, translated by George Long, pp. 105–252 of Volume 12, Great Books of the Western World (Chicago: Encyclopaedia Britannica, 1952), Book IV, Chapter 11, “About Purity,” pp. 240, 241. (In Book III, Chapter 7, Epictetus proposes another “unique” quality: shame and blushing.)

28. E.g., Jane Goodall, Through a Window: My Thirty Years with the Chimpanzees of Gombe (Boston: Houghton-Mifflin, 1990).

29. Plato, The Dialogues of Plato, translated by Benjamin Jowett (in Volume 7 of Great Books of the Western World), Laws, Book VII, p. 715.

30. Goodall, op. cit.

31. Charles Darwin, The Descent of Man and Selection in Relation to Sex (New York: The Modern Library, n.d.) (originally published in 1871) p. 449.

32. Leo K. Bustad, “Man and Beast Interface: An Overview of Our Interrelationships,” in Michael H. Robinson and Lionel Tiger, editors, Man and Beast Revisited (Washington and London: Smithsonian Institution Press, 1991), p. 250.

33. Toshisada Nishida, “Local Traditions and Cultural Transmission,” Chapter 38 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. 473.

34. Martin Daly and Margo Wilson, Homicide (New York: Aldine de Gruyter, 1988), p. 187.

35. Owen Chadwick, The Secularization of the European Mind in the 19th Century (Cambridge: Cambridge University Press, 1975), p. 269.

36. Solly Zuckerman, The Social Life of Monkeys and Apes (New York: Harcourt, Brace, 1932), p. 313.

37. Leslie A. White, “Human Culture,” Encyclopaedia Britannica, Macropaedia (1978), Volume 8, p. 1152.

38. Toshisada Nishida, “A Quarter Century of Research in the Mahale Mountains: An Overview,” Chapter 1 of Nishida, editor, The Chimpanzees of the Mahale Mountains, p. 34.

39. Henri Bergson, The Two Sources of Morality and Religion (New York: Holt, 1935).

40. Nishida, op. cit. (Note 38), p. 24. Chimpanzee folk medicine seems to have been independently rediscovered by other primatologists (Ann Gibbons, “Plants of the Apes,” Science 255 [1992], p. 921). Among pre-industrial humans, most plants are used for something. The botanist Gillian Prance and his colleagues found (private communication, 1992) that 95 percent of the rainforest trees accessible to a group of Bolivian indigenous peoples are employed—for example, the sap of a tree in the nutmeg family as a potent fungicide.

41. E.g., Raymond Firth, Elements of Social Organisation (London: Watts and Co., 1951), pp. 183, 184; D. Michael Stoddart, The Scented Ape: The Biology and Culture of Human Odour (Cambridge: Cambridge University Press, 1990), p. 126.

42. Napoleon A. Chagnon, Yanomamo: The Fierce People (New York: Holt, Rinehart, Winston, 1968), p. 65.

43. Desmond Morris, The Biology of Art (London: Methuen, 1962); R. A. Gardner and B. T. Gardner, “Comparative Psychology and Language Acquisition,” in K. Salzinger and F. E. Denmarks, editors, Psychology: The State of the Art (New York: Annals of New York Academy of Sciences, 1978), pp. 37–76; K. Beach, R. S. Fouts, and D. H. Fouts, “Representational Art in Chimpanzees,” Friends of Washoe, 3:2–4, 4:1–4. Oil paintings by a chimp named Congo, which today hang in several private collections, exhibit a gaudy abstract expressionism and are considered the best of the chimp oeuvres.

44. Birds, for example, recognize and mob a novel predator (or even a milk bottle) that frightened their ancestors four generations earlier. And speaking of milk bottles, soon after one blue tit pierced the metal foil cap of a milk bottle left on a doorstep and drank the cream, blue tits all over England are said to have begun drinking cream. (John Tyler Bonner, The Evolution of Culture in Animals [Princeton, NJ: Princeton University Press, 1980].) Of course no one knows who this pioneering bird was. This may not be learning by imitation, though. An already opened milk bottle and another bird present nearby and happy may be enough to give a naive bird the idea. (D. F. Sherry and B. G. Galef, Jr., “Social Learning Without Imitation: More About Milk Bottle Opening by Birds,” Animal Behaviour 40 [1990], pp. 987–989)

45. Zuckerman, op. cit., pp. 315, 316.

46. Nishida, “A Quarter Century of Research,” p. 12.

47. So could souls have provided consciousness back then? A deity responsible on a case-by-case basis for precision injection of souls into this immense host of tiny creatures over the full range of geological time would be a very fussy as well as a very inefficient creator. Why not design it right from the beginning, and let life run by itself? Would the god responsible for the subtle, elegant, and universally applicable laws of physics do such slapdash, error-ridden, journeyman work in biology—requiring hands-on attention to every pathetic little microbe when they already know perfectly well how to reproduce themselves and vast stores of information? Instead, all the god has to do is to encode directly into the DNA of a few ancestors whatever information souls are required to know. Souls and consciousness could then pass, on their own, from generation to generation, freeing the god for other matters, perhaps some of greater urgency. But if the information in the DNA has come to be through the patient evolutionary process, why is a god needed to explain the injection of data, genes, or souls in the first place?

48. A. I. Hallowell, “Culture, Personality and Society,” in Anthropology Today, A. L. Kroeber, editor (Chicago: University of Chicago Press, 1953), pp. 597–620; Hallowell, “Self, Society and Culture in Phylogenetic Perspective,” in Evolution After Darwin, Volume 2, S. Tax, editor (Chicago: University of Chicago Press, 1960), pp. 309–371. The contention that only humans are self-aware can be found in many philosophical and scientific disquisitions, e.g., Karl R. Popper and John C. Eccles, The Self and Its Brain (New York: Springer, 1977).

49. G. G. Gallup, Jr., “Self-Recognition in Primates: A Comparative Approach to the Bidirectional Properties of Consciousness,” American Psychologist 32 (1977), pp. 329–338.

50. A common literary and iconographic theme in medieval Europe beginning in the thirteenth century is an alleged propensity for apes to admire themselves in mirrors. Cf. H. W. Janson, Apes and Ape Lore in the Middle Ages and the Renaissance (London: University of London, 1952), pp. 212 et seq.

51. Montaigne, The Essays of Michel Eyquem de Montaigne, Book II, Essay XII, “Apology for Raimond de Sebonde,” translated by Charles Cotton, edited by W Carew Hazlitt, Volume 25 of Great Books of the Western World (Chicago: Encyclopaedia Britannica, 1952), p. 227. In a nearby passage, Montaigne quotes the Roman epigramist Juvenal: “What stronger lion ever took the life from a weaker?” But, as we’ve mentioned, lions routinely kill all the cubs on taking over a pride. This saves the male the trouble of caring for young not his, and helps bring the females back into heat.

52. E.g., R. L. Trivers, Social Evolution (Menlo Park, CA: Benjamin/Cummings, 1985), especially the chapter “Deceit and Self-Deception”; Joan Lockard and Delroy Paulhus, editors, Self-Deception: An Adaptive Mechanism? (Englewood Cliffs, NJ: Prentice-Hall, 1989).

53. C. G. Beer, “Study of Vertebrate Communication—Its Cognitive Implications,” in D. R. Griffin, editor, Animal Mind-Human Mind (Report of the Dahlem Workshop on Animal Mind-Human Mind, Berlin, March 22–27, 1981) (Berlin: Springer-Verlag, 1982), p. 264; E. W. Menzel, “A Group of Young Chimpanzees in a One-acre Field,” in A. M. Schrier and F. Stollnitz, editors, Behavior of Nonhuman Primates (New York: Academic Press, 1974).

54. Stuart Hampshire, Thought and Action (London: Chatto and Windus, 1959).

55. T. H. Huxley, Evidence as to Mans Place in Nature (London: Williams and Norgate, 1863), p. 132.

56. Letter of February 5, 1649, in Mortimer J. Adler and Charles Van Doren, Great Treasury of Western Thought: A Compendium of Important Statements on Man and His Institutions by the Great Thinkers in Western History (New York and London: R. R. Bowker Company, 1977), p. 12.

57. See, for example, Eugene Linden, Silent Partners: The Legacy of the Ape Language Experiments (New York: Times Books, 1986); Roger Fouts, “Capacities for Language in the Great Apes,” in Proceedings, Ninth International Congress of Anthropological and Ethnological Sciences (The Hague: Mouton, 1973).

58. For example, “Man is the only animal … that can use symbols” (Max Black, The Labyrinth of Language [New York: Praeger, 1968]); “Animals cannot have language … If they had it, they would … no longer be animals. They would be human beings” (K. Goldstein, “The Nature of Language,” in Language: An Enquiry into Its Meaning and Function [New York: Harper, 1957]); “There seems to be no substance to the view that human language is simply a more complex instance of something to be found elsewhere in the animal world” (Noam Chomsky, Language and Mind [New York: Harcourt Brace Jovanovich, 1972]). These examples are taken from Donald R. Griffin’s The Question of Animal Awareness, revised edition (New York: Rockefeller University Press, 1981). Only occasionally is a contrary note sounded (e.g., A. I. Hallowell, Philosophical Theology, Vol. 2 [Cambridge: Cambridge University Press, 1937], p. 94.)

59. Derek Bickerton, Language and Species (Chicago: University of Chicago Press, 1990), especially pp. 8, 15–16.

60. Bickerton, op. cit., proposes that the early speech of children is a “protolanguage” fundamentally different from fully developed human languages, that this protolanguage may be accessible to apes, and that it was used by our ancestors in the transition from apes to humans.