Back in September
Ember, M., C.R. Ember, and Bobbi Low. 2007. "Comparing explanations of polygyny." Cross-Cultural Research, 41(4): 428-440.
Polygyny is common in the ethnographic record. The vast majority of cultures known to anthropology allowed at least some men to have more than one wife simultaneously. This article compares various explanations of nonsororal polygyny, by far the most common type of polygyny. Multiple regression analyses of data for the societies in the Standard Cross-Cultural Sample indicate that the two main independent cross-cultural predictors of appreciable (i.e., more than occasional) nonsororal polygyny are high male mortality in war (resulting in an excess of females) and high pathogen stress, which seems to favor nonsororal polygyny to maximize genetic variation and disease resistance in progeny. High male mortality in war predicts particularly in nonstate societies.