"Their review explains why - at the level of societies - monogamous marriage norms have been so successful. Even though 85 percent of documented societies allow polygyny (one man marrying many women) and a very small number allow polyandrous marriage (one woman takes several husbands), societies that only sanction monogamous marriages have thrived. Moves toward institutionalised monogamy have been tied to the ascendancy of ancient Greece and Rome. (..) Polygyny creates conflicts among individuals with far-reaching consequences for the society as a whole."

https://theconversation.com/society-wide-benefits-of-monogamous-marriage-6908