@Cloverfr
" Is true that monogamy is very social, because polygamy is a taboo, however, even in cavern days couples stay in monogamy no for "social" reason but rather for survival reasons, imagine a cavern male with 5 mates and 16 children? "
There was no real monogamy in "cavern days". Even just 8000 years ago only 1 man reproduced per 17 women.
https://psmag.com/environment/17-to-1-reproductive-success
Even in modern history more men than women reproduce.
"In more recent history, as a global average, about four or five women reproduced for every one man."
There were men who have had sex with women and made children and then there were those who took care of those children. Those were either servants, slaves or just clueless husbands. Even now (with contraception and DNA-tests) in many places, paternity fraud results in as much as 10% of children being raised by a man who mistakenly thinks they are his own.
Anyway, real pure monogamy is socially enforced in humans. Simply put, there is a "safe strategy" of monogamy, but it should be enforced by society. And there is a "high-risk high reward" strategy of polygamy or cheating/cuckold. You either have a harem or make taken women cheat with you. By simple math, it is impossible to have 100 children with one woman, but it is very much possible to seduce 100 women and have hundreds of children with them. Also, STDs weren't so much of a problem back then and you were way more likely to die from a cold than from an STD.