The balance of nature needed to sustain live over the long term involves an incredibly complex interaction among millions of components. Scientists spent years and millions of dollars trying to create a sealed Biosphere that could be built on another planet and support human life with a carefully selected collection of plants and animals. It failed badly.

Man's attempts to improve the world by eliminating nuisance animals like wolves or to convert forests to agriculture have led to serious side effects. If we want the earth to continue to sustain human life, we need to be cautious in how we treat its natural areas.