Alice Dreger writing at The Atlantic:
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.
That's not the case, though, according to a recent paper in Human Nature co-authored by two anthropologists, Katherine Starkweather, a PhD candidate at the University of Missouri, and Raymond Hames, professor of anthropology at the University of Nebraska. While earning her masters under Hames' supervision, Starkweather undertook a careful survey of the literature, and found anthropological accounts of 53 societies outside of the "classic polyandrous" Tibetan region that recognize and allow polyandrous unions.
Indeed, according to Starkweather and Hames, anthropologists have documented social systems for polyandrous unions "among foragers in a wide variety of environments ranging from the Arctic to the tropics, and to the desert." Recognizing that at least half these groups are hunter-gatherer societies, the authors conclude that, if those groups are similar to our ancestors—as we may reasonably suspect—then "it is probable that polyandry has a deep human history."
Dreger writes that polyandry is common in societies with skewed "operational sex ratios," a.k.a. too many men, too few women. So is polyandry likely to emerge in India and China, Dreger wonders, two countries with skewed sex ratios? Go read the whole thing to find out.