No. 2156:
Earth Without People

Today, What would happen if we were gone. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

I recently did a program on George Stewart's 1949 book, Earth Abides.Stewart asked what would happen if all but a small band of humans were to suddenly die of disease. He saw a Paleolithic society reemerging and surviving. But he also gave a good deal of thought to the question, "How would Earth initially react to the removal of its dominant species?" Now, as if on cue, the New Scientist magazine asks, "What would happen if, one day, all humans were to vanish, with no survivors at all?" This time the question is raised, not by a fiction writer, but by several biologists.

What's astonishing is how alike the two visions are -- fiction and science, separated by 57 years. Both recognize the speed with which the biota would move in and overrun all existing construction. All that we've built would soon crumble. Little would be useable after a generation or so. 

Both talk about the rapid realignment of animal species. At first, rats, with access to our food stores, would prosper. Their population would swell, then recede. Packs of the more adaptable dogs would grow and roam the land. The cattle population would die off dramatically; but the hardier would survive in smaller numbers. 

In 1986, much of this process actually began. A large area around the Chernobyl nuclear meltdown was abandoned by humans. Rats and mice first flourished; then receded. Buildings have since crumbled, while dogs, wolves, and wild boar are all doing well.

The New Scientist article points out that, since the average eco-footprint of each human on earth is about 25 acres, our absence would result in huge adjustments. Nineteen percent of Earth's surface is now affected by light pollution. That would be gone. 

The balance of species would readjust. Many that presently enjoy human protection might vanish. Species of cattle, or of wheat, highly refined for human use, would evolve backward toward their earlier and more self-sufficient forms. 

So the New Scientist asks: If alien archaeologists were to arrive a hundred thousand years hence, would they know we'd been here? Beyond finding a few broken bones of our civilization they'd have other clues: lingering traces of odd chemicals in odd places. But Earth would long since have readjusted its atmospheric carbon dioxide. Ocean fish populations would've recovered quickly -- as did the North Atlantic cod, when WW-II put cod fishing on hold. 

The article concludes that Earth would forget us sooner than outer space would. Our radio signals to other stars would still radiate outward long after our earthly tracks were windblown and blurred. Yet, I wonder: Would Earth forget completely? For the creation does not stop. Another technological species would surely evolve and, perhaps, make a better job of it the next time.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Earth without Humans. New Scientist, 14 October, 2006, pp. 36-41.

See also Episode 2151, in which I talk about G. R. Stewart's book, Earth Abides. (New York: Fawcett, 1986/1949).

After a few years:

 The grass takes over 

A world without us:

A world without us

(photos by J. Lienhard)