Monarchy I will define as a system of government where the leaders are succeeded by their children or other family members and/or where the leaders pick their successors. By contrast, the leader of a republic is chosen by some set of unrelated people, anything from the citizens to a council of aristocrats to a ruling committee. There's something odd that I've come to recognize recently. Until recently, nearly all societies much larger than a city-state have been ruled by monarchs. But over the last few centuries, many monarchies have either become weakened to de facto republics or abolished outright, with their successors establishing de jure republics. Has anyone ever considered why this odd trajectory has happened? It's been hard for me to find out very much on this question.