The Nature Conservancy logo. Protecting nature. Preserving life.

North America is a land shaped by elephants. (And pronghorns like the one above — but more on that later.)

10,000 years ago — a blink of the evolutionary eye — members of the elephant family such as mammoths and mastodons roamed our grasslands, influencing nearly every plant and animal that lived there.

They were part of one of the greatest assemblages of large mammals to ever roam the Earth, with great herds that rivaled those of Africa.

Giant sloths and tapirs, wild camels and horses, cheetahs and lions: All thrived here.

Some conservation biologists believe it’s time to bring them — or at least ecologically similar species — back to America.

Pleistocene rewilding, as this idea is called, is frequently placed in the same wacky camp as UFO investigations and Bigfoot biology.

It is almost impossible for critics, including Conservancy scientists, to discuss it without mentioning "Jurassic Park".

But maybe Pleistocene rewilding shouldn’t be so quickly dismissed.

Conservationists frequently point to the ecologically important roles played by fire, rivers, wetlands and climate. Large animals can also play an important role in shaping whole landscapes.

We know, for instance, the prairie is much healthier with bison herds.

Large herds of mammoths, wild horses and camels shaped the landscape dramatically — as the evidence increasingly demonstrates. Connie Barlow’s book, "The Ghosts of Evolution," describes many now marginal plants in North America (like osage orange and honey locust) that evolved to be dispersed by feeding elephants.

The pronghorn — the only true North American Pleistocene mammal to remain — evolved to outrun cheetahs. Today it races only ghost predators.

But didn’t the large Pleistocene mammals “naturally” go extinct?

That’s a subject of some debate, but paleoecologists like Paul Martin present strong evidence that the large mammals were wiped out quickly by the first humans to enter the continent.

The animals had not evolved with humanity like the large animals of Africa, and were quickly eliminated — what is called the overkill hypothesis.

Tapirs and camels belong here as surely as bison and grizzly bears. While many of the Pleistocene species are extinct, ecologically similar species remain. South American camels — like guanacos and vicunas — could easily be reintroduced to grasslands.

Even Indian elephants — yes, elephants — could play the role of mammoths and mastodons.

We don’t have to start big with something like, say, releasing elephants across the continent. That, obviously, is akin to "Jurassic Park."

But we could start small. As Joel Berger of the Wildlife Conservation Society writes: “No one can deny historical niches are unfilled today … Why not a humble beginning — say, on a hundred fenced hectares, or a thousand, or even ten thousand?”

Why not? Such a beginning could reveal important new insights about North American ecological processes — and help bring home our continent’s true diversity of large animals.

- This was written by Matt Miller for the Cool Green Science Blog and is republished with permission here.
Born to rewild
It is almost impossible for critics to discuss 'Pleistocene rewilding' without mentioning 'Jurassic Park.'