The basic outline of world economic history is surprisingly simple. Indeed it
can be summarized in one diagram: figure 1.1. Before 1800 income per person
—the food, clothing, heat, light, and housing available per head—varied across
societies and epochs. But there was no upward trend. A simple but powerful
mechanism explained in this book, the Malthusian Trap, ensured that shortterm gains in income through technological advances were inevitably lost
through population growth.