So, far be it from me to be misogynist (heh), I just came across this article on Vikings. Apparently, the Viking attacks began as a response to a lack of women and stress on obtaining the same. This was a result of the practice of female infanticide common to the culture. Fewer girls = fewer potential wives, so young men sally forth to obtain resources to obtain wives. And, although not mentioned in the article, if some of them die off in raids, that helps to reduce the strain on the others.
This accords with my own theory of polygamy and violent culture. As Tim Harford points out polygamous societies can actually be economically beneficial for the women involved, as it provides them with an amount of upward mobility not available in a monogamous society. This theory does not account very well for the problems this raises for other members. However, the balance can be returned if we posit that these young men, rather than being disenfranchised and run out of the community, are put to use in some way which will thin out their numbers. So it's hardly surprising that most traditionally polygamous societies also tend be a bit more . . . visceral than other cultures. I would also invert the claim that polygamy causes violence, as discussed after the riots in France. Instead, it is cultures predisposed to violence which leads to polygamy.
Just my thought.