Rants from the Hill: Pleistocene rewilding
"Rants from the Hill" are Michael Branch's monthly musings on life in the high country of Nevada's western Great Basin desert.
In a 2006 article [PDF] in The American Naturalist, a small herd of perfectly respectable conservation biologists advocates a bold ecological restoration project they call “Pleistocene Rewilding.” The concept itself is outrageously wild. First of all, “rewilding” is the process of reintroducing species to ecosystems from which they have been extirpated—usually by that big bully, Homo Notsosapiens. Think wolves in Yellowstone. Pleistocene rewilding, by contrast, is the incredible idea that we can enhance ecosystem health by reintroducing many of the large mammals that were driven to extinction between 10,000 and 13,000 years ago. The so-called “pre-Columbian benchmark” of 1492 is the commonly used target for restoration efforts. To achieve this benchmark we just figure out how the world looked on the day Chris Columbus made landfall—say, at about cocktail hour—and then restore North American ecosystems to that condition by extirpating exotic species, reintroducing natives, and rehabilitating habitat. It isn’t easy to do, but at least it’s easy to understand.
Then along come these provocative Pleistocene Rewildatators, who ask why we’re so stuck on 1492. In fact, it was about 13,000 years ago that humans showed up in North America, where they wasted no time poking spears into everything that moved—a habit that probably contributed to the disappearance of large mammals. And the mass extinction of megafauna during the Pleistocene—along with a secondary wave of extinctions resulting from the disappearance of those keystone species—caused severe damage to the fabric of North American ecosystems, which have been slowly fraying and unraveling ever since. Since the fossil record gives us a pretty good idea of what beasts roamed here 13,000 years ago, before the arrival of human hunters, why not select an ecological restoration benchmark that is closer to Pleistocene cocktail hour? Why not acknowledge that North American ecosystems are full of holes—ecological niches that have gone unoccupied for 10,000 years—and then do our best to fill those holes by reintroducing large mammals?
Now here’s the fun part. It turns out that by the time Columbus arrived, most of the cool stuff was long gone—and in this sense the usual pre-Columbian restoration benchmark actually describes a world in which biodiversity was already radically impoverished. Pleistocene North America was in fact home to a living bestiary of outrageous creatures, including various species of horses, donkeys, camels, muskoxen, sloths, tapirs, peccaries, cheetahs, lions, and Proboscideans (mammoths and mastodons), not to mention giant short-faced bears, ferocious saber toothed cats, and fierce dire wolves (and, to depart from mammals for a moment, the nine-foot long sabertooth salmon and the ten-foot tall terror bird as well). Among the charismatic megafauna that made it through the bottleneck of Pleistocene extinctions are animals every westerner knows to be equally fantastic: coyote, wolf, bison, grizzly, cougar, and pronghorn antelope, to name a few.
But these survivors just aren’t the same without their lost neighbors. Take pronghorn, for example, a remarkable species that can run up to 60 miles per hour. Coyotes, wolves, mountain lions, and every other major predator in North America is so incredibly slow compared to pronghorn that predation by these animals simply cannot have provided the selection pressure necessary to create the pronghorn’s unimaginable speed. Where, then, did this amazing speed come from? From the extinct American cheetah, which, although it has been absent from North American ecosystems for at least 10,000 years, chased the hell out of pronghorn for almost two million years before that.
Although the American cheetah and many other Pleistocene megafauna are long gone, advocates of Pleistocene rewilding believe we can use “extant conspecifics and related taxa” (read: kinfolk) to represent extinct species in North American ecosystems. While the several species of Pleistocene tapirs are extinct, for example, they could be represented by the mountain tapir, which survives today in South America. The extinct North American camel could be replaced by the dromedary out here in the desert, and by the vicuña or guanaco in the more mountainous parts of the West. Pleistocene North America was also home to mammoths and mastodons, megaherbivores which played a number of important roles as keystone species. If it sounds crazy to suggest that modern elephants might be used to fill this empty ecological niche, consider this: Asian elephants are more closely related to extinct North American mammoths than they are to surviving African elephants. For the vanished American cheetah and American lion we’d simply use their African cousins. Finding big cats to reintroduce might not be difficult, since more than 1,000 cheetahs are currently kept in the U.S., and more lions live on Texas ranches than in all American zoos combined.
Actually, Pleistocene rewilding has already begun in North America, if we count several successfully reintroduced species. After the peregrine falcon was driven to the brink of extinction as a result of DDT exposure during the 1950s and 60s, populations were recovered through the introduction of seven subspecies from the U.S., Europe, South America, and Australia—subspecies that served effectively as “proxy taxa” for the vanished Midwestern peregrine falcon. Or, consider the California condor, which was widely distributed in North America during the Pleistocene, but afterwards survived only along the west coast. After successful reintroduction in California, the condor was subsequently reintroduced to the Southwest, where the species had enjoyed no prolonged residency for ten millennia. Or, take that iconic animal of the American West, the wild mustang. Horses, which are native to North America but went extinct here 12,000 years ago, were reintroduced by Spaniards in the late fifteenth century. The wild mustangs I often see out here in Silver Hills are descendents of the conquistadores’ steeds, and consequently are considered non-native. But if we just adjust our timescale from the pre-Columbian benchmark to the Pleistocene—if we wind the clock back from five centuries ago to 125 centuries ago—we might say that Columbus and his compadres were innovators in Pleistocene rewilding. In Nevada we have constant controversy over the BLM’s annual roundup of “non-native” wild mustangs from public lands. But the problem is not that the horses are non-native, but rather that they decimate the range because the predators with which they co-evolved have been absent for millennia. We don’t have too many horses. We have too few lions.
I get it that sticking a bunch of lions and tigers and bears (Oh My!) in Nevada might have complications. But I see no reason to allow legitimate scientific counterarguments to stand in the way of imagination. What would it be like to hike Silver Hills and see not only pronghorn, as I often do, but pronghorn using every fiber of their evolutionary speed to outrun a cheetah in hot pursuit? What if a visit to our foothills spring meant not dodging fly-encrusted cow pies but instead witnessing elephants spraying spring water on their dusty, weathered backs? What if a resident herd of camels gnawed up some of these invasive woody shrubs and restored open grasslands where cattle have left nothing but sage, thistle, and cheat? What if it became a Fourth of July tradition to drink white Russians made with camel’s milk and smoke juicy peccary sausages and tasty tapir steaks on the barbeque?
And I hold no truck with the argument that we shouldn’t introduce these megafauna because they’re dangerous. I already have to keep rattlers from killing my dogs, coyotes from attacking my lazy cat, and cougars from eating my children. I suspect we’d all be energized and invigorated by making the salutary transition from Couch Potato to Potential Prey. And while I wouldn’t wish misfortune on any of my neighbors—because I have so few that I can’t afford to lose too many—I’d welcome the use of lions to purge Silver Hills of folks who don’t do their fair share of work on our dirt road. Well, and maybe the guy who talks too much at the mailboxes. And for sure the lady who delivers the mail.
But enough rhapsodizing about the usefulness of lions. What I really mean to say is that to fully inhabit a landscape—especially one as remote and inhospitable as the one I call home—requires both experiential contact and leaps of imagination. If the Great Basin desert impresses us with the sheer, incomprehensible vastness of its space, it is also important to triangulate this place within the vastness of time. To envision Silver Hills as it was 13,000 years ago is also to begin to imagine what it might look like 13,000 years from now. Why only think long and hard about our place, when we might also think deep about it? I’m not saying that Pleistocene rewilding will work right away. I realize that it might take ten or twelve thousand years, and that a few of the neighbors will have to be sacrificed for the good of the megafauna. But think of it conceptually rather than literally. Rewilding: to become wild again after having lost wildness. That is something we all need. And the first step in rewilding must be to reintroduce the possibility of the marvelous to our imagination of the land.
Michael P. Branch is Professor of Literature and Environment at the University of Nevada, Reno, where he teaches American literature and environmental studies. He has published five books and many articles on environmental literature, and his creative nonfiction has appeared in Utne Reader, Orion, Ecotone, Isotope, Hawk and Handsaw, Whole Terrain, and other magazines. He lives with his wife and two young daughters at 6,000 feet in the western Great Basin desert of Nevada.
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Image of mammoth art courtesy Flickr user Tony Case.
Image of "wild" mustang courtesy Flickr user Reno Tahoe.