1. Edward O. Wilson, Sociobiology: The New Synthesis, 2nd ed. (1975; Cambridge, MA: Belknap Press of Harvard University Press, 2002), 4.
2. Charles Darwin, The Origin of Species by Means of Natural Selection, (London: J. Murray, 1859).
3. Wilson, On Human Nature (New York: Bantam Books, 1979).
4. Robert L. Trivers, “The Evolution of Reciprocal Altruism,” The Quarterly Review of Biology 46, no. 1 (1971): 35–57.
5. John Tierney, “The Search for Adam and Eve,” Newsweek 111 (January 11, 1988; 1992): 46–52.