Anyone knows when the greek/roman (or anyone else) start prohibiting polygamy and why?
There are many many facts that would account for monogamy :
- Gender ratio - The gender ratio at birth is about 1:1. If there is no large scale deaths in males, then polygamy would essentially leave many men wifeless.
- Religion - Christianity bans adultery and polygamy. Given the dominance of Christian Europe in the last few centuries, this has probably had a lot of influence.
- Human Nature - Nobody wants to share. polygamy can probably lead to uncomfortable living conditions.
- Economics - Supporting a wife and children is expensive. Supporting more than one wife and extra children would probably be out of the reach of majority of population in ancient times.
I might also point out that monogamy was already an established custom in the monarchies that have since become democracies, so the correlation (if any), should only be made between monogamy and monarchies. Since most of the known world was monarchial in nature, this essentially means that we don't have enough data for a correlation.