Hedge funds are paid to anticipate the way the world is heading. So it was notable that a few months ago Nir Bar Dea, the boss of Bridgewater, the world’s largest hedge fund, was in Abidjan, the commercial capital of Ivory Coast, to co-host a summit calling for more money for the World Bank. For Mr Bar Dea, Africa’s population explosion is one of those “long term trends that people don’t pay attention to.”