Tens of millions of people across more than half the states in sub-Saharan Africa need urgent food aid, but the causes are often complex and varied. Food crises were once primarily triggered by natural disasters like droughts.
But according to research by the UN Food and Agriculture Organization, man-made causes are increasingly to blame. These include conflict and poor governance, as well as HIV/Aids.
Rural poverty, international trade barriers, overpopulation, deforestation, poor use of land and environmental problems can also be factors.