Actually, the problem in the world is that there are too many rich people. - Paul R. Ehrlich

Too many rich people in the world is a major threat to the human future, and cultural and genetic diversity are great human resources.

Trying to separate the contributions of nature and nurture to an attribute is rather like trying to separate the contributions of length and width to the area of a rectangle, which at first glance also seems easy. When you think about it carefully, though, it proves impossible.

Overdrafts on aquifers are one reason some of our geologist colleagues are convinced that water shortages will bring the human population explosion to a halt. There are substitutes for oil; there is no substitute for fresh water.