"But before the advent of agriculture our ancestors were remarkably democratic, healthy and content with their social lives."

We have absolutely no way of knowing that since they didn't have writing. It's called "pre-history" for a reason. When European explorers arrived in the Americas with with things made out of iron, glass, and cloth, the Native Americans wanted all of it, along with traps, firearms, and alcohol. They killed almost every beaver in North America to trade for it. Those horses that the Plains Indians heavily incorporated into their culture and stole from each other were an invasive species. Those warriors were just as self interested as the white man. A war bonnet for the Sioux was just like the ribbons that a soldier wears. Donning one could only be described as arrogance since it showed how many times the brave had counted coup or killed an enemy. They adorned their women with trinkets just as many cultures do to show off their wealth. They were exactly like us, except they didn't live as long.

If you want to see a legitimate traditional culture that hasn't changed since ancient times, check out the Taliban. Most of them can't read either.