Contact and the Columbian Exchange

When Columbus's ships reached the Caribbean, they linked two halves of the world that had been separate for 12,000 years — and unleashed a biological catastrophe. Old World diseases like smallpox, to which Native Americans had no immunity, killed perhaps 90% of the hemisphere's population within a century, the deadliest demographic collapse in recorded history. It was disease, more than steel, that emptied the Americas for conquest — a reminder that pathogens, not just armies, decide the fate of worlds.