The brown revolution: on the rise of "megacities", primarily in developing countries, as their economies move to a more urban basis.
In the long run, that is good news. If countries now industrialising follow the pattern of those that have already done so, their city-dwellers will be both more prosperous and healthier. Man is a gregarious species, and the words "urbane" and "civilised" both derive from the advantages of living in large settlements.
History also shows, though, that the transition can be uncomfortable. The slums of Manchester were, in their time, just as awful as those of Nairobi today. But people moved there for exactly the same reason: however nasty conditions seemed, the opportunities of urban life outstripped those of the countryside. The question is how best to handle the change.
