Or maybe, “why is monogamy so prevalent?” Tbh I don’t have the stats on hand to feel confident asking it that second way, hence the title question, but in either case the question still stands.
Or maybe, “why is monogamy so prevalent?” Tbh I don’t have the stats on hand to feel confident asking it that second way, hence the title question, but in either case the question still stands.
Monogamy isn’t actually practiced by most of humanity. The existence of STIs that have evolved in the human population is ample enough evidence of that. STIs simply wouldn’t exist if monogamy was actually the norm. People may find it easier at times to pair off for sexual activity, but if monogamy was the norm then there wouldn’t be any opportunity for STIs to thrive.
The prevalence of paired relationships in many countries has to do with laws, taxes, and health benefits. (US perspective here) Many US states make it impossible for people in poly relationships to have and raise kids together. Those US states that don’t make it legally impossible make things difficult. Even for people in poly relationships without kids, there are issues of health care and access to family members in hospital and care settings, etc. All of this is a lot of extra effort that many people just aren’t willing to deal with, even if they wanted to be in a poly relationship.
From a purely mechanical perspective, human genitalia are physically evolved for multiple partners (simultaneous or serial). Species that are evolved for monogamy have very very different sexual organs.