In 100 years we will be an entirely urban species

7 August 2010

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Doug Saunders has visited 30 villages and cities on five continents to explore the great irreversible migration: from the countryside to vast megacities. This is the single most important change mankind faces

One last, crucial, calming fact for the anxious. It can feel to a native city-dweller as if the floods of newcomers to a city mean that the population as a whole is expanding wildly, beyond our ability to control it.

But rural-migrant enclaves — I call them ‘arrival cities’ in my new book by that title — are not causing population growth; in fact, they are ending it. When villagers migrate to the city, their family size drops, on average, by at least one child per family, almost always to below the steady-population rate of 2.1 children. Look at what happened in Iran and Turkey. In those countries, mothers were having between five and eight children each in the 1980s; they now have fast-shrinking populations, entirely because of urbanisation. Without massive rural-to-urban migration, the world’s population would be growing at a far faster pace than it is today.

So thanks to megacities, at some point this century the population of the world will stop growing. After reaching a peak, for the first time in history there will stop being more and more humans each year, and the prospect of a Malthusian population crisis will end. This will be a direct result of urbanisation and the flow of money, knowledge and education from the cities back to the villages.

When will the population peak? No one can be certain. Mrs Zlotnik’s team places the date around 2050, with 9 billion people in the world; a tiny difference in average family sizes would have huge consequences. But it will happen. The urbanisation of the species will, in the end, be our salvation.

Doug Saunders’s book Arrival City: How the Largest Migration in History is Reshaping Our World is published by Heinemann. He is the European bureau chief for the Canadian newspaper the Globe and Mail.