For more than thirty years, humankind has known how to grow enough food to end chronic hunger worldwide. Yet while the “Green Revolution” succeeded in South America and Asia, it never got to Africa. More than 9 million people every year die of hunger, malnutrition, and related diseases every year—most of them in Africa and most of them children. More die of hunger in Africa than from AIDS and malaria combined. Now, an impending global food crisis...