Editor's Note: Evolution has been for nearly a century and a half the intellectual core of biology. More recently evolution has been recognized as having shaped and stabilized the surface of the earth as the only habitat for life. The concept is attractive: evolution is building an open-ended, developmental system, self-guided, self-repairing, capable of accommodating all travails in due course, even to the point of building into the biosphere more room for life, more diversity, and greater stability of habitat. Surely, according to this concept, biotic resilience is sufficient to accommodate the activities of Homo sapiens, one species of the several million now on earth, all the product of this magnificently versatile and effective process.

But the timing is off. In the long term of thousands of millennia the glorious vision of a benign and effective evolutionary resilience may be appropriate. In the time of our lives it is the principles of succession and impoverishment that apply.

Succession enjoys all the optimism of any developmental progression, no matter how mean the origins: a bank account, growing with the accrual of interest. Growth is salutary, almost by definition.