Matt Ridley

22. Margulis 1981:

23. Cosmides and Tooby 1981; Hurst and Hamilton 1992: 24. Anderson 1992; Hurst 1991b; Hurst 1992b: 25. Werren, Skinner, and Huger 1986; Werren Hurst 1990; Hurst 1991c:

1987;

26. Mitchison 1990:

27. L: Hurst, interview; see also Parker, Baker, and Smith 1972 and Hoekstra 1987 for additional, but not rival, features of the evolution of anisogamy and two genders:

28. Frank 1989:

29. Gouyon and Couvet 1987; Frank 1989; Frank 1991; Hurst and Pomiankowski 1991:

::: 356 :::

NOTES

30. Hurst 1991a:

31. Hurst and Hamilton 1992:

32. Hurst, Godfray, and Harvey 1990:

33. Hurst, Godfray, and Harvey 1990.

34. Olsen and Marsden 1954; Olsen 1956; Olsen and Buss 1967: 35. Lienhart and Vermelin 1946:

36. Hamilton 1967:

37. Cosmides and Tooby 1981:

38. Bull and Bulmer 1981; Frank 1990:

39. Bull and Bulmer 1981; J: J: Bull, interview: 40. Frank and Swingland 1988; Charnov 1982; Bull 1983; J: J: Bull, interview: 41. Warner, Robertson, and Leigh 1975:

42. Bull 1983; Bull 1987; Conover and Kynard 1981: 43. Dunn, Adams, and Smith 1990; Adams, Greenwood, and Naylor 1987: 44. Head, May, and Pendleton 1987:

45. J: J: Bull, interview.

46. Bull 1983; Werren 1991; Hunter, Nur, and Werren 1993.

47. Trivers and Willard 1973:

48. Trivers and Willard 1973:

49. The sex ratio of presidential children was first noticed by Laura Betzig and Samantha Weber of the University of Michigan: 50. Trivers and Willard 1973:

51. Austad and Sunquist 1986:

52. Clutton-Brock and 1ason 1986; Clutton-Brock 1991; Huck, Labov, and Lisk 1986:

53. T: H: Clutton-Brock, interview:

54. Clutton-Brock, Albon, and Guinness 1984: 55. Symington 1987:

56. For baboons, see Altmann 1980; for macaques, see Silk 1983, Simpson and Simpson 1982, and Small and Hrdy 1986; for a general summary, see Van Schaik and Hrdy 1991; for howler monkeys, I rely on K: Glander, interview; for a skeptical view of this data, T: Hasegawa, correspondence: 57. Hrdy 1987:

58. Van Schaik and Hrdy 1991:

59. Goodall 1986:

60. Grant 1990; Betzig and Weber 1992.

61. Grant 1990; V: J: Grant, correspondence.

62. Bromwich 1989:

63. K: McWhirter: 'The gender vendors: ' Independent newspaper, London 27

October 1991, pages 54-55:

64. B: Gledhill, interview:

NOTES

::: 357:::

65. For zebra finches, see Burley 1981; for red-cockaded woodpeckers, see Gowaty and Lennartz 1985; for bald eagles, see Bortolotti 1986; for other hawks, see Olsen and Cockburn 1991:

66. N: D: Kristof: 'Asia, Vanishing Point for As Many As 100 Million Women: '

International Herald Tribune, 6 November 1991, page 1: 67. Rao 1986; Hrdy 1990:

68. M: Nordborg, interview:

69. Bromwich 1989:

70. James 1986; James 1989; W: H: James, interview: 71. Unterberger and Kirsch 1932:

72. Dawkins 1982: