Could advances in technology, genetics and artificial intelligence lead to a world in which economic inequality turns into biological inequality? asks the historian and writer Yuval Noah Harari. Inequality goes back at least 30,000 years. Hunter-gatherers were more equal than subsequent societies. They had very little property, and property is a pre-requisite for long-term inequality. But even they had hierarchies. In the 19th and 20th Centuries, however, something changed. Equality became a dominant value in human culture, almost all over the world. Why?