Many evolutionary psychologists like to talk about polygyny. Some say it’s a good thing for the individuals involved. Some say it’s a bad thing. But they tend to agree that this is just how we evolved. Polyandry, if it’s discussed at all, is generally dismissed as being insignificant.
A new study just out suggests we shouldn’t dismiss polyandry so quickly, particularly not if we want to talk about evolved behavior. Last year, Katherine Starkweather and Raymond Hames published “A Survey of Non-Classical Polyandry” (pdf) in Human Nature.
Terms first. What do Starkweather and Hames mean by “polyandry”?
In general, we define polyandrous unions as a bond of one woman to more than one man in which the woman has relatively restricted sexual rights toward the men, and the men toward the women, as well as economic responsibilities toward each other and toward any children that may result from the union.
They note that this arrangement may be formal, in which the family created becomes a household, or informal, in which the sexual relationships and responsibilities are recognized but the family does not all live together. For a polygynous equivalent to informal polyandry, consider the old (at least) royal practice of a king who maintained mistresses and their children on estates away from the royal palace.
“Non-classical” has largely meant “ignored” up to this point for reasons pointed out in the Atlantic article that drew my attention to the survey.
So how is it that, in spite of all this evidence of polyandry accumulating steadily in the literature, anthropologists for so long passed along the “it’s virtually non-existent” story? Starkweather and Hames suggest anthropology has been accidentally playing a scholarly version of the Telephone Game.
In 1957, George Murdock defined polyandry in a seminal text as “unions of one woman with two or more husbands where these [types of union] are culturally favored and involve residential as well as sexual cohabitation.” Using such a strict definition, Murdock could accurately say polyandry was extremely rare; almost no cultures have polyandry as the dominant and most preferred form of family life.
Then subsequent scholars mis-repeated Murdock’s remark; polyandry went from being understood as “rarely culturally favored” to “rarely permitted.” Thus mating diversity that was known to exist became relatively invisible in the big story told by anthropology about human mating. (If you write off every exception to a supposed rule, you will never think to challenge the rule.)
In an email interview with me, Starkweather remarked, “I don’t think that anyone, including Murdock, was operating from an explicitly sexist standpoint. However, I do think that the definitions of polyandry, and thus perceptions about its rarity, may have been due at least in part to the fact that an overwhelming percentage of anthropologists collecting data and shaping theory at the time were men.” During Murdock’s time, “there seemed to be a fairly pervasive belief that polyandry didn’t make any sense from a male’s perspective.”
In doing this, Starkweather and Hames were testing several theories about why polyandry occurs:
- Fraternal polyandry provides a means of limiting property division during inheritance. (Common to classical polyandry.)
- Polyandry provides additional labor to support offspring where resources are very limited.
- Where there are fewer females, polyandry may both be an outcome of female mate choice and provide some males their only opportunity to reproduce.
- In places where males are absent from the home for long periods, polyandry is “the devil you know”.
- Where male mortality is high, polyandry is a means of providing an “extra” father for children.
The results? A lot of variability. That is to say that, while polyandry was found under conditions that would support any of those theories, it was also found in societies that do not have those “drivers” for polyandry. Yes, non-classical polyandry also has a strong fraternal component (67% of societies studied), as theory 1 would predict, it also had a strong non-fraternal component (53%). Prolonged male absences occur in 67% of these polyandrous societies but not in the other 33%, and the difference isn’t statistically significant at this sample size.
There were some statistically significant factors, however. Polyandrous societies tend heavily (75%) toward the egalitarian, with less political stratification, and 83% of them are hunter-gatherer/forager societies, not quite half of which include some elements of horticulture. They tend to have more males than females (75%). They also strongly tend toward males producing a majority of the food (64%) and toward males dying younger than women (75%).
The fact that I smiled when I read the parts of the results section dealing with those last two factors tells you something about the quality of most of papers in the field of evo psych that I read. You see, after looking at the numbers that their study produced, they put them in context.
A major limitation of our analysis is that we are looking at trends within polyandrous societies and are unable to evaluate whether these trends exist in a cross-cultural sample of polyandrous and non-polyandrous societies. For example, we found an association between male productive labor time and high adult male mortality and polyandry[…]. Cross-culturally, however, male productive labor times (Ember 1983) and mortality rates (Kruger and Nesse 2006) are greater than female labor time and female mortality.
In other words, there’s a good chance this doesn’t tell us anything special about polyandrous societies. It was so refreshing to see. They do something very similar when discussing sexual jealousy in polyandrous households, noting that such jealousy is an issue for polyandry but that the literature on polygyny shows similar problems with jealousy.
To be fair to the researchers, they’re not evolutionary psychologists. They’re anthropologists, and they deal with the question of behavioral adaptations only in one brief section, in which they discuss how polyandry complicates our picture of paternal investment in children, particularly with regard to children who may not be related to the “fathers” involved.
The results of this study provide another challenge to common evolutionary psychology viewpoints in that the polyandry we see happens, by and large, in egalitarian, hunter-gatherer societies. Those, of course, are the societies closest to those in which evolutionary psychologists posit that our behavior evolved.
Does that mean we evolved to be polyandrous? Not exactly. There’s a good bit of polygyny in those societies as well and a bunch of serial monogamy. It would be difficult to look at the variety of forms of relationships in these groups and suggest that we’ve evolved to seek out any single one of them. At best, an argument could be made, looking at the variety and flexibility of these arrangements, that we’ve evolved with a drive to form familial groups for the purpose of caring for children, no matter how the exact composition of that group might have to change to fit the circumstances.
Starkweather and Hames argue just that in their paper, although they don’t argue that their specific analysis directly supports that idea. They couch their statements with the appropriate caveats, noting that they are extrapolating from the present to the past. Still, they note, “it is probable that polyandry has a deep human history.”
It will be interesting to see whether the evolutionary psychology community incorporates that observation going forward.
Starkweather KE, & Hames R (2012). A survey of non-classical polyandry. Human nature (Hawthorne, N.Y.), 23 (2), 149-72 PMID: 22688804