Will Success Doom Homo sapiens?
In the current issue of Orion Magazine, Charles C. Mann recalls watching Lynn Margulis, show a time-lapse video to students at the University of Massachusetts. It featured Proteus vulgaris, a bacterium that lives in the gastrointestinal tract of humans.
The video showed a small, wobbly P. vulgaris in a shallow, circular glass petri dish. Remarkably, the bacterium is capable of dividing every fifteen minutes!
Mann reports, "The class gasped. The cells in the time-lapse video seemed to shiver and boil, doubling in number every few seconds, colonies exploding out until the mass of bacteria filled the screen." Margulis stated that in just thirty-six hours this single bacterium could cover the entire planet in a foot-deep layer of single-celled ooze. Twelve hours after that, it would create a living ball of bacteria the size of the earth.
What prevents our guts from exploding from such rampant, unchecked multiplication of the bacterium in our bodies?
Margulis identified three constraints:
– the limited size of its habitat (portions of the human gut)
– the scarcity of nourishment (food proteins)
– the presence of competing organisms
Thus, Margulis assured the students, a calamitous population explosion never happens and the population of P. vulgaris in our guts remains roughly steady.
However, in the petri dish, there is no competition. Nutrients are provided. The habitat is congenial. Mann describes the scene in the video, “The bacterium hits the first inflection point and rockets up the left side of the curve, swamping the petri dish in a reproductive frenzy. But then its colonies slam into the second inflection point: the edge of the dish. When the dish’s nutrient supply is exhausted, P. vulgaris experiences a miniapocalypse.” The species is perpetuated because, by luck or superior adaptation, a few members survive the collapse and reproduce.
Such population flares and collapses are not unique to P. vulgaris. believes this scenario can be applied to HUMANS. Currently, our population is growing exponentially. We are taking over large areas that were not previously occupied. We are behaving as if there was no force to oppose our biological urge to make more of ourselves. But, she advised, we may soon overwhelm our environment. And then, like the bacterium in the petri dish, most of our population will drown in our own wastes or starve from lack of food. To Margulis, Homo sapiens resembles the temporary flush of the briefly fortunate.
Reference article by Charles C. Mann
Published in the November/December 2012 issue of Orion magazine