In the middle of the last century, high-yielding varieties of rice, wheat and maize were introduced across much of the developing world, transforming agriculture. Farm incomes increased, food prices fell and poverty declined. The Green Revolution passed Africa by, however. Since 1960, per capita cereal output in Asia has increased by 44 per cent and in South America by 48 per cent despite rapid population growth. In Africa it has declined by 13 per cent.