Apparently, indigenous South American societies were quite a bit more democratic than we thought. Albeit in their own way.
Candidates for senator in Tlexcallan, for example, had to stand firm while their constitutions hurled insults and objects at them, presumably to test their ability to handle being mocked during a debate, drilled on the law for two years and put through various ordeals before they could take their seat. I can't see the average American senator tolerating even a bit of those. Well, except the insult-hurling, which has apparently always been a part of politics.
And the study has helped archaeologists learn patterns - for example, cities dominated by plazas rather than palaces - that show when a society may be more "democratic" in some sense.
Worth remembering for world building. (Also, can we have more fantasy democracies? Please?)