Medea's Choice

Nothing lasts forever. That's the truth, and there's nothing anyone can do about it--and our planet is no exception. Fortunately, Earth still has a billion or more years left as a life-supporting world, at least according to conventional wisdom. According to unconventional wisdom, however, our planet may already be in its old age.
The Medea Hypothesis (named after the Greek mythological woman who killed her own children after Jason left her) was proposed by geologist Peter Ward as an alternative to the better-known Gaia hypothesis. While the Gaia hypothesis suggests that life continuously maintains an ideal environment for itself, the Medea hypothesis states that life periodically destroys its own environment. And indeed, many of the mass extinctions in the fossil record seem to have been caused, at least indirectly, by biological activity. In other words we--humanity--are simply the most recent Medea event.
The Gaia hypothesis, of course, was one of the ideas that fed into the "environmentalism fad" of the 1960s and 70s, and even today much of what we know about environmentalism and ecology is based on it. But what if the Medea hypothesis is actually true? Is there any way to reconcile an environmental conscience with an understanding of the Medea hypothesis?
The answer is yes. The microbes that were responsible for the mass extinctions in the Permian and the Ordovician periods had no way of understanding what they were doing. Humans, fortunately, do. And that is why environmental efforts still matter, even if the Gaia hypothesis may not be true. We, unlike any life form that came before us, have the mental capacity to choose not to destroy our environment--and in doing so allow life on Earth to last at least a little while longer.
Perhaps this time, Medea can choose not to kill her children.