What if I told you there was a society in which all the young men marry elderly widows? If you had even an entry level understanding of evolutionary biology, you might think I was making it up. The Tiwi of North Australia, at first glance, seem like solid support for the old school view of the Mind as a Blank Slate. According to anthropologists C.S.M. Hart and Arnold R. Pillig: "... nearly every man in the tribe in the age group from thirty-two to thirty-seven was married to an elderly widow...But very few of them had a resident young wife." The Tiwi seem like a blatant exception to an assumption widely held by evolutionary psychologists - of a universal male attraction toward younger fertile partners. In a paper just published in Evolution, Culture, and the Human Mind, my former student Sarynina Nieuweboer and my colleague Bram Buunk (from the University of Groningen), joined me to take a closer look at the puzzling Tiwi.

The occasional marriage between a younger man and an older woman could be dismissed as random variation, and there's nothing too puzzling about a young man who is attracted to a relatively older woman who still displays all the cues to youth and health (as in the case of Demi Moore and Ashton Kutcher).  But a whole society in which younger men marry older widows seems to pose a biological puzzle, for several reasons. Rich Keefe and I had published a paper in Behavioral & Brain Sciences in which we argued for an evolutionary account of age differences in mate choice. Keefe and I claimed that men were attracted not so much to younger women, as previous psychologists had assumed, but to women during the years of peak fertility. Because menopause is a feature of our species, not of any particular culture, it made evolutionary sense that older men in all societies would be attracted to relatively younger women (who are more likely to be fertile). Indeed, we reported data from several societies and historical time periods that supported that argument. For example, on the remote island of Poro in the 1920s, older men married substantially younger women - "trophy wives" just like the ones sought by CEOs of American corporations. Several anthropologists commenting on our paper chimed in with consistent data from yet other societies.

Social psychologists Alice Eagly and Wendy Wood have suggested that many such sex differences in mating behavior might disappear in a society in which gender differences in social power were erased. If their social roles model applied to Tiwi society, you might expect Tiwi women to be relatively powerful. But Tiwi society is highly patriarchal. In fact, Tiwi men dictate who a woman is to marry. So the Tiwi pose a puzzle from both sociocultural and evolutionary perspectives. And there's another biological puzzle there: Even if you are not thinking in evolutionary terms, you have to wonder: how does a society in which young men marry post-menopausal women reproduce its members?

For the answer to this puzzle, see my follow-up post (The Mind as a Coloring Book 2)

For Further Reading 

Hart, C.W.M., and Pillig, A.R. (1960). The Tiwi of North Australia. New York: Holt.

Kenrick, D.T., Nieuweboer, S., & Buunk, A.P. (2010). Universal mechanisms and cultural diversity: Replacing the blank slate with a coloring book. Pp. 257-271 in M. Schaller, A. Norenzayan, S. Heine, T. Yamagishi, & T. Kameda (eds.) Evolution, culture, and the human mind. NY: Psychology Press.

Kenrick, D.T., & Keefe, R.C. (1992).  Age preferences in mates reflect sex differences in mating strategies.  (target article)  Behavioral & Brain Sciences, 15, 75- 91.

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