So at twenty-five you introduce yourself on a dating site as ‘a twenty-five-year-old heterosexual woman who lives in London and works in a fashion sh… - Yuval Noah Harari

The so-called Facebook and Twitter revolutions in the Arab world started in hopeful online communities, but once they emerged into the messy offline world, they were commandeered by religious fanatics and military juntas.

The food surpluses produced by peasants, coupled with new transportation technology, eventually enabled more and more people to cram together first into large villages, then into towns, and finally into cities, all of them joined together by new kingdoms and commercial networks.

In 2012 about 56 million people died throughout the world; 620,000 of them died due to human violence (war killed 120,000 people, and crime killed another 500,000). In contrast, 800,000 committed suicide, and 1.5 million died of diabetes. Sugar is now more dangerous than gunpowder.