Tsapelas, I, HE Fisher, and A Aron (2010) “Infidelity: when, where, why.” in WR Cupach and BH Spitzberg, The Dark Side of Close Relationships II, New York: Routledge, pp 175-196
Pair-bonding is a hallmark of humanity. Data from the Demographic Yearbooks of the United Nations on 97 societies canvassed in the 1990s indicate that approximately 93.1% of women and 91.8% of men married by age forty-nine (Fisher, 1992). Worldwide marriage rates have declined somewhat since then; but today 85% to 90% of men and women in the United States are projected to marry (Cherlin, 2009). Cross-culturally, most who marry wed one person at a time: monogamy. Polygyny is permitted in 84% of human societies; but in the vast majority of these cultures, only 5% to 10% of men actually have several wives simultaneously (Frayser, 1985; Murdock &White, 1969; van den Berghe, 1979). Monogamy, wedding one mate at a time, is the norm for Homo sapiens.