William Tucker provokes some thoughts on the link between polygamy and violence in a culture. Though I do not agree with his presupposition of evolutionary systems, I think he might be on to something.
Species and societies that practice polygamy end up with a bachelor herd, a gaggle of unmated males who are very unhappy with their lot. Competition among males becomes much more violent because the stakes are so highits all or nothing. The peaceful monogamous contract is gone.
When 18th- and 19th-century Europeans realized polygamy was common in the backward portions of the world, they had an easy explanation. Polygamy was a more primitive form of marriage. Advanced societies had evolved out of it. Then they discovered the hunter-gatherers and a different explanation offered itself. Polygamous societies had remained backward precisely because they were polygamous. Polygamy creates a huge inequality where all the wealthhowever little there may be of itand all the women are concentrated among the more successful men. (Think Saudi Arabia.) Societies bog down. Social advancement becomes very difficult.
Monogamy is not natural. Its a human construct. But I also happen to think it is the greatest social achievement in the history of mankind. Peaceful advanced societies never would have emerged without it.
So now the entertainment industry is going to start asking, What would America look like without it? Lots of luck.