Original: Christopher Boehm (1999) "Hierarchy in the Forest: The Evolution of Egalitarian Behavior" page 198-208 Harvard university press Middle Paleolithic societies, unlike Lower Paleolithic and early Neolithic ones, consisted of bands that ranged from 20 to 30 or 25 to 100 members and were usually nomadic.
Simplified: References Christopher Boehm (1999) "Hierarchy in the Forest: The Evolution of Egalitarian Behavior" page 198 Harvard university press Leften Stavros Stavrianos (1991).