10 000 years ago, the world's population was very little. Four hundred years ago, the number were over 500 million. Today, it's still growing more faster than ever before. Now the problem may be the greater one in the world. How do you think of it? What will happen to the world? What will happen after a hundred years? This means we must grow more food and smaller families with fewer or healthier children. If we won't do these, the results will be very bad. There will not have enough space to stand in on the earth. This must be know to us.