Some few lies in the mix. Mankind living in the woodlands and plains, close to nature, is not "full and productive" lives, it is not being all we can be. We need society, urban society, books, written communication, detailed innstitutional memories and learnings hard won, passed from generation to grow as mankind. Many of the tribal peoples in the "New World" were cannibals, and raiders and slavers of neighboring tribes according to opportunity. Others lived hardscrabble, marginal existances, and all were illiterate. They had spoken language and some few tribes had some detailed image records, knotted strings, painted and sculpted images, but no real written language. Their institutional memories conveyed from generation to generation were fables, full of imaginary things, a diffuse mix of little value, moraity, legal system and invention wise.