In his latest video, the ever-informing CGP Grey explains the history of plagues – Cholera, Smallpox, Typhus, Measles, Influenza and the Black Death – and the complex coordination of circumstances that made it possible for each disease to travel across the ocean from the highly populated Old World to the sparsely inhabited New World in the 15th and 16th centuries, where no such pandemics had ever existed before.
The lack of new world animals to domesticate, limited not only exposure to germs sources but also limited food production, which limited population growth, which limited cities, which made plagues in The New World an almost impossibility. In the old, exactly the reverse. And thus a continent full of plague and a continent devoid of it. So when ships landed in the new world there was no Americapox to bring back. The game of civilization has nothing to do with the players, and everything to do with the map. Access to domesticated animals in numbers and diversity, is the key resource to bootstrapping a complex society from nothing — and that complexity brings with it, unintentionally, a passive biological weaponry devastating to outsiders. Start the game again but move the domesticable animals across the sea and history’s arrow of disease and death flows in the opposite direction.