John Chilton (The Emirates Economist) has a recent posting about polygamy in Canada.
These are societies that close themselves off from the world and construct codes and practices that perpetuate polygyny. Like teenage boys being exiled from the community. Child brides. Denying girls an education that would make leaving more attractive. Parents, particularly fathers, determining who their daughters will marry. A system of institutions, values, brainwashing and beliefs is created to keep women in check. Add to this that men are physically stronger. It's curious of course that women in these cult societies very often defend them. I won't pretend to understand that, but we do know that many of us have a tendency to defend what we have lived especially if we have been taught that there is evil outside your community and your community is under siege.
For my own musings on the topic several years ago, see this, where I added
As a male who would likely have risked being left without a partner in a society that permitted polygamy, I am understandably opposed to polygamy out of pure self-interest. It strikes me that in a society of free choice, permitting polygamy only increases the demand for women as potential marriage partners, thus making women better off relative to men, in comparison with the situation under monogamy [a point also discussed by John Chilton]. ...
For more on the economics of polygamy, see this chapter in David Friedman's Price Theory text, especially the first portion of the chapter.