A plea to find ways to feed a world of ten billion people has started the World Agricultural Forum meeting in St. Louis. Nobel laureate Norman Borlaug says it will take a combination of solutions to prevent starvation by the middle of century. Borlaug says experts differ on when the world population will hit ten billion, but he’s confident it will be before the end of this century. The world population is now about six-billion. About 300 people have protested at the opening sessions, but they’ve been kept across the street from the hotel where the meeting is being held – and the proests have been peaceful.