This long but very good article addresses overpopulation. I've been concerned about this issue for a long time and wondered why so little was said about it. We can't simply fill up the planet until we are standing shoulder to shoulder. There has to be land for food and shelter and there has to be clean water. There has to be land for rainforest to provide the planet's lungs and there has to be land for animals. The article points out again what has been said before... the best way to reduce population is to educated women and provide safe, affordable birth control.