The article about forms of slavery among the First Nations was interesting (thanks! )although not particularly well documented and limited to North America. The Aztecs and Incas almost certainly kept slaves. Most neolithic agricultural societies developed slavery at about the same time they learned to write.

The article was very detailed and comprehensive,  within the North American focus. I knew a little, next to nothing really, of the social structure of PNW First Nations. I had read that they practiced status displays,  valued private wealth and lived in what amounted to a class hierarchy. So I think the info there is pretty good; it agrees with what I've already in essays with better source citations. Thanks.

It did  however suggest that cannibalism was not rare among indigenous, which is a controversial claim. It was appears to have been extremely rare. See what you think of this; it's similar to the articles you sent me.

http://www.native-languages.org/iaq13.htm