What set Acosta apart from other Conquest chroniclers was that he didn’t posit an either-or, this-or-that opposition between savagery and civilization. Rather, the traveling Jesuit offered a secular evolutionary account of the transition between primitive and complex societies. He identified human history as passing through definable stages. First: simple societies which mostly hunt and gather, and which have neither leader nor religion. Second: close-to-the-land settled communities that were governed loosely by elders. Third: a kingdom or empire that exercises dominion and is organized around a clear political hierarchy and religion. According to Acosta, America was home to all three. Societies like the Inka and Aztecs had reached the highest levels of civilization. Other societies were perhaps moving toward more complexity but their mode of life still fell within one of the first two stages.

— America, América by Greg Grandin