Fascinating study by primatologists that when one troop of primates discover the use of tools (ie for extracting termites from nests) there will be correpsonding tool use from a different troop despite no contact. But that’s not necessarily relevant - just interesting.

Something happened when hunter-gatherer societies settled. The centralised storage of excess foodstuff and its use towards the cultural (rather than survival) gave groups the ability to build these monuments and perhaps these ideas spread with trade; initially flint tools or similar and later with more specialised goods.

I do love archaeology and anthropolgy.