Discuss the link that the writer is making between polygamy and the dawn of agriculture

The early societies of hunters and gatherers were into polygamy.  Back then there was no limit as who they could be with as they roamed the land in search of food.  When they learned how to farm and raise animals, they began to settle into communities and as a result drew boundaries as to who they can be with and what belonged to them. As a result, it started the decline of polygamy.

they all focused on themes about the inevitability of death.