Polyandry, and what it doesn't mean about human nature

Twitter showed me this Atlantic article about polyandry, which begins this way:

For generations, anthropologists have told their students a fairly simple story about polyandry — the socially recognized mating of one woman to two or more males. The story has gone like this:

While we can find a cluster of roughly two dozen societies on the Tibetan plateau in which polyandry exists as a recognized form of mating, those societies count as anomalous within humankind. And because polyandry doesn’t exist in most of the world, if you could jump into a time machine and head back thousands of years, you probably wouldn’t find polyandry in our evolutionary history.

I’m not an anthropologist, so maybe that’s why this is not what I’ve told my students.

I’ve told them that polyandry emerges in human sociosexual systems under circumstances of extreme resource scarcity and/or an operational sex ratio with substantially more males than females. As such, they absolutely DO appear in our evolutionary history. They are part of the extreme variety, diversity, plasticity, and adaptability of human sociosexual systems. Just as humans can survive on virtually diet provided by the earth, from almost exclusively fish to almost exclusively plants, so we can find a reproductive system suitable to any environment in which we find ourselves. (This is the story as I learned it from Bobbi Low’s work. A student of hers was on my dissertation committee. These things do tend to travel in intellectual families.)

What I didn’t know was how many more polyandrous cultures have been studied that I wasn’t aware of, and the many variations on polyandry that exist or have existed! I had, as the article suggests, been under the impression that it was found primarily – if not exclusively – in the Tibetan cultures identified. It’s FASCINATING!

The paper itself (PDF) provides a teachable moment relevant to my critique of Sex at Dawn. It concludes with the kind of language that I think the S@D authors have misunderstood as meaning “explicit, conscious decision-making”:

Polyandry seems to occur as a result of strategizing by both males and females. Males are likely responding to a lack of available women (owing to an imbalanced sex ratio, high rates of polygyny, or other factors) and strategizing to improve their reproductive fitness by attempting to achieve paternity. In essence, where a man’s reproductive fitness is concerned, sharing a wife may be better than having no wife at all. Females are responding to what seem to be risky environments (ones in which adult males are likely to die or, in some cases, be absent from home for long periods of time), strategizing to gain protection and provisioning from an additional husband.

This is “strategizing” in the sense that their GENES are strategizing; the individuals aren’t deciding, either independently or in community discussion, like, “Hey, what we need here is some polyandry.” These systems emerge as a result of the same selection processes that gave us ears and thumbs and pre-frontal cortices. We didn’t decide to have those, either. They emerge, quite literally, the way flocks of birds of shoals of fish emerge. The fish don’t “decide,” but shoaling definitely is a strategy.

So, in case any of ya’ll read it and thought to yourself, “But they’re saying that women are thus and such kind of people and men are so-and-so,” in the same way S@D mistakenly supposes that such language is about character: no. Traits are not like character traits. The mathematics and economics of reproductive fitness are not our personalities