Michael Specter

All the food we eat - every grain of rice and kernel of corn - has been genetically modified. None of it was here before mankind learned to cultivate crops. The question isn't whether our food has been modified, but how.

Until the Nineteen-Eighties, when Deng Xiaoping designated the area as China's first special economic zone, Shenzhen had been a tiny fishing village. Suddenly, eleven million people appeared, seemingly out of nowhere; factories sprang up, often housed in hastily constructed tower blocks.

By themselves, genetically engineered crops will not end hunger or improve health or bolster the economies of struggling countries. They won't save the sight of millions or fortify their bones. But they will certainly help.

In some of the great cities of Europe - Paris, Vienna, Prague, and Brussels - tourists bored with life above ground can descend below. All these cities have sewer museums and tours, and all expose their underbelly willingly to the curious. But not London, arguably the home of the most splendid sewer network in Europe.