Supplementary material from "Greater wealth inequality, less polygyny: rethinking the polygyny threshold model"

  • Cody T. Ross (Creator)
  • Monique Borgerhoff Mulder (Contributor)
  • Seung Yun Oh (Contributor)
  • Samuel Bowles (Creator)
  • Bret A. Beheim (Creator)
  • John Bunce (Creator)
  • Mark Caudell (Creator)
  • Greg Clark (Creator)
  • Heidi Colleran (Creator)
  • Carmen Cortez (Creator)
  • Patricia Draper (Creator)
  • Russell D. Greaves (Creator)
  • Michael Gurven (Creator)
  • Thomas Headland (Creator)
  • Janet Headland (Creator)
  • Kim Hill (Creator)
  • Barry S. Hewlett (Creator)
  • Hillard Kaplan (Creator)
  • Jeremy M. Koster (Creator)
  • Karen Kramer (Creator)
  • Frank W. Marlowe (Creator)
  • Richard McElreath (Creator)
  • David Nolin (Creator)
  • Marsha Quinlan (Creator)
  • Rob Quinlan (Creator)
  • Caissa Revilla-Minaya (Contributor)
  • Brooke A. Scelza (Creator)
  • Ryan Schacht (Creator)
  • Mary Shenk (Creator)
  • Ray Uehara (Creator)
  • Eckart Voland (Creator)
  • Kai Willfuhr (Creator)
  • Bruce Winterhalder (Creator)
  • John Ziker (Creator)
  • Monique Borgerhoff Mulder (Creator)
  • Hillard Kaplan (Creator)
  • Jeremy Koster (Creator)
  • Bruce Winterhalder (Creator)



Monogamy appears to have become the predominant human mating system with the emergence of highly unequal agricultural populations that replaced relatively egalitarian horticultural populations, challenging the conventional idea—based on the polygyny threshold model—that polygyny should be positively associated with wealth inequality. To address this polygyny paradox, we generalize the standard polygyny threshold model to a mutual mate choice model predicting the fraction of women married polygynously. We then demonstrate two conditions that are jointly sufficient to make monogamy the predominant marriage form, even in highly unequal societies. We assess if these conditions are satisfied using individual-level data from 29 human populations. Our analysis shows that with the shift to stratified agricultural economies: (i) the population frequency of relatively poor individuals increased, increasing wealth inequality, but decreasing the frequency of individuals with sufficient wealth to secure polygynous marriage, and (ii) diminishing marginal fitness returns to additional wives prevent extremely wealthy men from obtaining as many wives as their relative wealth would otherwise predict. These conditions jointly lead to a high population-level frequency of monogamy.
Date made available2018
  • Greater wealth inequality, less polygyny: Rethinking the polygyny threshold model

    Ross, C. T., Mulder, M. B., Oh, S. Y., Bowles, S., Beheim, B., Bunce, J., Caudell, M., Clark, G., Colleran, H., Cortez, C., Draper, P., Greaves, R. D., Gurven, M., Headland, T., Headland, J., Hill, K., Hewlett, B., Kaplan, H. S., Koster, J., Kramer, K., & 14 othersMarlowe, F., McElreath, R., Nolin, D., Quinlan, M., Quinlan, R., Revilla-Minaya, C., Scelza, B., Schacht, R., Shenk, M., Uehara, R., Voland, E., Willfuhr, K., Winterhalder, B. & Ziker, J., Jul 1 2018, In: Journal of the Royal Society Interface. 15, 144, 20180035.

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    32 Scopus citations

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