As any biologist would predict, this success led to an increase in human numbers--slow at first, then rapid, tracing Gause's S-shaped curve. We began rising up the steepest part of the slope in the sixteenth or seventeenth century. If we follow Gause's pattern, growth will continue at delirious speed until the second inflection point, when we have exhausted the global petri dish. After that, human life will be, briefly, a Hobbesian nightmare, the living overwhelmed by the dead. When the king falls, so do his minions; it is possible that in our desperation we might consume most of the world's mammals and many of its plants. Sooner or later, in this scenario, Earth will again be a choir of microorganisms as it has been through most of its history. It would be foolish to expect anything else, Margulis thought. More than that, it would be strange. To avoid destroying itself, the human race would have to do something deeply unnatural, something no other species has ever done or could ever do: constrain its own growth