Not until the beginning of the 20th century did Europe's urban populations finally become self-sustaining: before then, constant immigration of healthy peasants from the countryside was necessary to make up for the constant deaths of city dwellers from crowd diseases.
Jared DiamondA blueprint for disaster in any society is when the elite are capable of insulating themselves.
Jared DiamondI'd rather spend my leisure time doing what some people call my work and I call my fun.
Jared DiamondWhy were there far more species of domesticated animals in Eurasia than in the Americas? The Americas harbor over a thousand native wild mammal species, so you might initially suppose that the Americas offered plenty of starting material for domestication.
Jared Diamond