Rocketing up the growth curve, human beings “now appropriate nearly 40% . . . of potential terrestrial productivity.” This figure dates from 1986—a famous estimate by a team of Stanford biologists. Ten years later, a second Stanford team calculated that the “fraction of the land’s biological production that is used or dominated” by our species had risen to as much as 50 percent. In 2000, the chemist Paul Crutzen gave a name to our time: the “Anthropocene,” the era in which Homo sapiens became a force operating on a planetary scale. That year, half of the world’s accessible fresh water was consumed by human beings.
Lynn Margulis, it seems safe to say, would have scoffed at these assessments of human domination over the natural world, which, in every case I know of, do not take into account the enormous impact of the microworld. But she would not have disputed the central idea:Homo sapiens has become a successful species, and is growing accordingly.
If we follow Gause’s pattern, growth will continue at a delirious speed until we hit the second inflection point. At that time we will have exhausted the resources of the global petri dish, or effectively made the atmosphere toxic with our carbon-dioxide waste, or both. 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 our fall might also take down most mammals and many plants. Possibly sooner, quite likely later, in this scenario, the earth will again be a choir of bacteria, fungi, and insects, 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 unnatural.