Government failures are causing high food prices and shortages, not overpopulation. In 1798, Thomas Malthus predicted mass starvation when he wrote An Essay on the Principle of Population. Paul Ehrlich restated this belief in 1968 in his book The Population Bomb, both men and many others, have made doomsday forecasts in which Earth's population goes beyond sustainable levels and as a result much of the population starves. The recent high food prices beg the question: has our population become too large, are the Malthusians right?
High food prices are the result of a multitude of government failures, not the size of our population. Biofuel mandates are artificially diverting farming practices away from growing food; government policies putting price controls on food, banning food exports, and protective tariffs on food are also resulting in underproduction. These policies do not allow farmers to see true price signals and as a result farmers do not produce the amount of food that is actually demanded.
Ronald Bailey has a great article on this topic at Reason.