The Economist’s famous Big Mac Index was invented as a way of judging what the exchange rate between two currencies ought to be. If a Big Mac costs a dollar in the US and three kronor in Sweden (a third difference) but the actual exchange rate is 50 per cent then it follows that the dollar is overvalued.
Whatever its merits, the popularity of the index shows that food – and, more specifically, how much money people spend on food – can tell us a lot about society. Madagascar, where I was this January, and its relationship to rice provides an excellent example of how the price of a staple can tell the story of a nation.
