The movement of people across space in search of better conditions — the most ancient and most consequential human behavior after reproduction itself, the process through which Homo sapiens populated the entire planet, built every civilization, and continues to shape the demographics and politics of every country on earth — and the subject of the most consequential political conflicts of the contemporary world.
Every human being alive today is descended from migrants. The evidence from ancient DNA makes this inescapable: every population that has ever been studied shows evidence of being the product of multiple migrations, admixtures, and replacements over tens of thousands of years. The 'native population' of any country, traced back far enough, was itself a migrant population that arrived and displaced whatever was there before. This fact does not settle contemporary migration debates — current migration raises genuine questions about integration, welfare states, and political community — but it does establish the starting point: the movement of people is not an anomaly or a crisis. It is the condition from which everything else in human history follows.