This is a jarring thought:

A paper by Diego Comin, Erick Gong, and myself was just published in the American Economic Journal: Macroeconomics. We collected crude but informative data on the state of technology in various parts of the world in 1000 BC, 0 AD, and 1500 AD.

1500 AD technology is a particularly powerful predictor of per capita income today. 78 percent of the difference in income today between sub-Saharan Africa and Western Europe is explained by technology differences that already existed in 1500 AD – even BEFORE the slave trade and colonialism.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.