Although monogamy seems the norm, in reality it is the exception, not only at the cultural level, but at the historical level. Monogamy is a relatively modern development, which emerged in very specific circumstances that laid the foundations. Even among animals, only 3% of mammals form long-term partners with only one spouse.
However, perhaps we should rethink monogamy or be flexible when adopting new types of affective and sexual relationships. Even our happiness could be resentful otherwise.
Throughout our early history, polygyny or a male with several females was routine. According to the psychologist David Barash, from the University of Washington, Seattle:
Monogamy was essentially a social treatment whereby powerful men of polygyny agreed to renounce their harems in exchange for a degree of social peace.
Monogamy also had advantages. A recent analysis found that, from hunter-gatherers to industrial societies, the greater the father’s investment, the more monogamous the society is. As we evolved into larger brains, keeping babies alive required more effort and food. The children of men who were scattered in too many families were less likely to survive.
The development of weapons could have balanced the playing field, because dominant men were no longer able to defend themselves against competitors who were weaker (but armed). That aligns with another idea: monogamy helped social stability. If a few men monopolize all women, that leaves many passersby discontented.
Advantages of polygamy
Monogamy, currently, does not seem to offer a special advantage. For example, a study conducted a few years ago suggests that men from polygamous cultures survive monogamous cultures after discarding socio-economic differences: men over 60 from 140 countries who practice polygamy in varying degrees lived on average 12% more than men from 49 countries mostly monogamous.
The explanation could be both social and genetic. Men who continue to father children between the ages of 60 and 70 could take better care of their bodies because they have more mouths to feed. But the evolutionary forces that operated for thousands of years could also select the longest-lived men in polygamous cultures.
However, in most societies studied, polygamy favors women. Being patriarchal societies, where the sons carry the inheritance and inherit the family property, in polygamous societies a woman has the opportunity to be matched above her social position, that is, men with enough resources to support several women and the offspring.
In the short term, it seems that it will be increasingly easy to meet suitable potential partners for us (from apps to big data). Divorcing will be easier than ever (a mere blockchain procedure ). Faced with this new ecosystem, perhaps monogamy (at least in the medium or long term) will end up being a rare sight of people who feel more at ease with an exclusive partner.