Men have a physical advantage in plough agriculture, not so much in hoe agriculture. In the latter, men tried to collect many more wives for economic reasons.
Neandertals lived in much colder areas than humans originally evolved in, and they didn't seem to have sewing needles, instead wearing animal hides. The late Judith Harris theorized that they were still hairy, and that modern humans mostly ate them as a result: https://www.edge.org/response-detail/11509
Monogamy is not just a feature of the west. Per Jack Goody, "monogamy is part of a cultural complex found in the broad swath of Eurasian societies from Japan to Ireland that practice social monogamy, sexual monogamy and dowry", linked to intensive plough agriculture.
Even Islam constrains the number of wives to four, which is less polygynous than the pre-Islamic norms of the area in which it arose (monogamy was more of a Roman thing).
Polygamous marriage is still not legal in the liberal societies you're referring to. And within them the cultures which appear capable of maintaining above-replacement fertility are those like the Amish & ultra-orthodox Jews.
Men have a physical advantage in plough agriculture, not so much in hoe agriculture. In the latter, men tried to collect many more wives for economic reasons.
Neandertals lived in much colder areas than humans originally evolved in, and they didn't seem to have sewing needles, instead wearing animal hides. The late Judith Harris theorized that they were still hairy, and that modern humans mostly ate them as a result: https://www.edge.org/response-detail/11509
Monogamy is not just a feature of the west. Per Jack Goody, "monogamy is part of a cultural complex found in the broad swath of Eurasian societies from Japan to Ireland that practice social monogamy, sexual monogamy and dowry", linked to intensive plough agriculture.
Even Islam constrains the number of wives to four, which is less polygynous than the pre-Islamic norms of the area in which it arose (monogamy was more of a Roman thing).
Polygamous marriage is still not legal in the liberal societies you're referring to. And within them the cultures which appear capable of maintaining above-replacement fertility are those like the Amish & ultra-orthodox Jews.