It is nearly two hundred years since people first began to worry about the growth of the world's human population and how it would be possible to find enough food for everyone in the future. Recently this problem has become more urgent as modern medicine has learnt how to protect people from many diseases, so that they live longer and longer.In 1850 there were about a thousand million people in the world.Today there are four times as many,and early tn the next century the world population will be double what it is now. Even today many millions of people are starving or suffering from the effects of having too little to eat it seems hopeless to try to find enough food for twice as many people in such a short time.