Of course, a positive growth rate might be taken as evidence that a population is below its optimum.

The optimum population is, then, less than the maximum.

A finite world can support only a finite population; therefore, population growth must eventually equal zero.

The rate of population growth in the United States is slightly below that required to reproduce itself.

But as population became denser, the natural chemical and biological recycling processes became overloaded, calling for a redefinition of property rights.

The optimum human population of earth is zero