When Paul Martin looked across the desert landscape near the University of Arizona he saw a very different world, at least in his mind's eye. As an expert on the end of the Pleistocene epoch, which ended around 13,000 years ago, he saw North America awash with animals that are no longer here.
He saw elephants, and camels, and cheetahs, and horses, roaming freely across the continent. These native animals disappeared either long before humans arrived, or just as the first Americans entered the scene.
Martin, now retired from Arizona, began talking with friends about what it would be like to restore some of that magic to a land that has lost some of the great beasts that once dominated the landscape.
He went so far as to propose that some effort be made to reintroduce some of those extinct animals, or at least their closest-living relatives.
"The idea did not attract much attention," says Harry Greene, professor of ecology and evolutionary biology at Cornell University. But sometime later Greene was discussing Martin's vision with one of his graduate students, Josh Donlan, now a doctoral candidate at Cornell.
That discussion led to a meeting at a New Mexico ranch of experts from across the country, including Martin, to discuss what may be one of the boldest proposals to come out of the environmental movement in decades.
The result was a commentary written by Donlan and published in the prestigious journal Nature.
In that report, 11 contributors called for the reintroduction of elephants and cheetahs and other extinct animals in a long-range program that would result in some species roaming freely across the land, just as they had thousands of years ago.
They called it "Pleistocene Rewilding."
The result was predictable, although Greene admits even he was somewhat taken aback. Some folks just thought it was a terrific idea. Others, including some leading conservation organizations, thought it was awful.
"One guy called me a pointy headed academic," says Greene, who prior to this had led a fairly quiet life as an expert on snakes. "I've never gotten hate mail before."
Dolan says some people accused the scientists of wanting to play God, recreating a land that has changed much since the late Pleistocene. They cite examples of human meddling that led to disaster. Right on Martin's doorstep, for example, Arizona officials reintroduced the crayfish a few years ago, and they've since spent millions trying to bring it under control.
Little wonder that ranchers, who pale at the thought of a coyote (not to mention wolves) didn't look fondly on the idea of lions and cheetahs prowling through their area.
But not all of the response was negative, especially the feedback from folks who had taken the trouble to read Donlan's commentary.
"It's been completely all over the map," Greene says. Favorable editorials, and comments from some members of the National Academy of Sciences, described the proposal as "forward looking."
Although some news reports indicated that elephants, as well as cheetahs and other fierce predators from Africa, might soon be set free to drag people out of their beds at night, that's not at all what the researchers had proposed.
The re-introduced animals would be in tightly-controlled environments, and the program would be phased in over decades, and begin relatively small. Think turtles. But not little turtles.
At the meeting on the New Mexico ranch, which is owned by media mogul Ted Turner, the scientists decided on a first step. They would reintroduce the Bolson tortoise, which is about the size of a coffee table, to part of the ranch that would be carefully controlled.
That first experiment should begin soon, and it addresses one fundamental goal of the project. The Bolson tortoise, now found only in northern Mexico, will likely become extinct in the near future if it cannot be reintroduced in a protected environment.
Likewise, many animals that are close relatives of those that roamed North America during the Pleistocene are endangered. Donlan cites the Bactrian camel, now endangered in the Gobi desert, as a replacement for the extinct camels of North America. It's not exactly the same animal, but pretty close.
These repatriated animals would be free to roam within a protected environment, but that doesn't mean they could wander freely into our cities to terrorize the locals.
Greene sees fences. Miles and miles of fences. Keeping animals in, and keeping humans at a safe distance.
So who's going to do all this, and where's the money going to come from? Greene sees some help coming from ranchers, which is pretty surprising given the turmoil from the reintroduction of wolves in the Yellowstone area. He has met with many ranchers in Arizona, he says, and some are beginning to see a marriage of very different partners.
Rewilding, Greene notes, could be very good for ranching, and for tourism.
Some ranchers he has worked with "are interested in combining ranching with science and conservation as a means of saving that way of life," Greene says.
An elephant could clear a lot of brush on an Arizona ranch, he adds, paving the way for grasses that can feed a herd of cattle. So an elephant could become sort of a ranch hand, and a draw for tourists who, presumably, would stay around for a hamburger.
Meanwhile, other extinct species could be left to prey on animals that have flourished since their predators disappeared. That, the researchers contend, would enhance bio-diversity.
They point to the reintroduction of wolves as evidence of that.
"That has had a spectacular effect," Greene says. Wolves have thinned the ranks of elk, and made the survivors more cautious, so vegetation has rebounded in many areas near Yellowstone, providing food for other animals.
"Beavers have come back," Greene says. "I think that's just spectacular."
Various studies have shown that the reintroduction of the wolf has altered the landscape remarkably, returning it more and more to what it was like before humans decided to eliminate this top predator.
Maybe the same reintroduction could be done for other species. Very slowly. Rebuilding the ecology just one brick at a time.