Earlier quoted context omitted.
Here it goes: http://gesd.free.fr/graeber13.pdf
I have yet to read his latest book, but the reviews seem quite promising. Basically he and his co-author challenge the view that we got more intelligent over time, and they do back their conclusions with extensive references.
Well for one, it's not out yet, so all we have are reviews. It is available for pre-order and will be on the 9th of November though.