The Scottish countryside will soon be home to creatures nearly as strange to Britain as the monster that's said to inhabit the depths of Loch Ness. This spring, 17 beavers will be released into a remote area of rivers and deciduous forest. Hunted to extinction throughout Europe, beavers haven't roamed Britain's wilderness for almost 500 years. Their presence has been dearly missed, at least by some conservationists. Beaver dams create the kind of wetlands that many birds, fish and mammals rely on—and that costly land-management programs in Scotland and elsewhere have striven to re-create, with spotty results. Ecologists would like to invite back other long-lost species to help restore the natural balance. To save the country's vegetation from deer, which have doubled to 2 million since the start of this decade, an Oxford University biologist late last year called for reintroducing the lynx—a wildcat that died out in Britain 1,300 years ago.
Nature has long been a popular cause in Europe. Brits love their countryside of hedgerows and fields, the French their vineyards and the Germans their hiking forests. But in recent years conservationists have set their sights on the more distant past, when Europe's forests and meadows were replete with elephants, hippopotamuses, rhinoceroses and big cats. Some ambitious conservationists are now advocating a return to norms of wilderness that date back to the Pleistocene era, more than 11,000 years ago.
The megafauna from that period, which had a dramatic impact on the environment around them, are a vital, missing part of Europe's ecosystem, argue proponents of Pleistocene rewilding, as the movement is known. Elephants, for example, keep forests from growing too dense. Large predators increase the survival odds of their prey by thinning the weak from the ranks. Importing Asian and African beasts similar to the ones that roamed prehistoric Europe would increase biodiversity and restore a natural equilibrium, with the biggest mammals once again at the top of the food chain.
Nobody is advocating allowing elephants and lions to run amok in this densely populated region. The bigger animals—including water buffalo and Heck cattle, bred to resemble the massive aurochs that died out in the 17th century—would live in enclosed parks. But wilding proponents would give free rein to a long list of lesser mammals, including the beaver and the lynx, which some people fear could be destructive. Some landowners recoil at the thought of beavers gnawing down trees and flooding their property; the Scottish Parliament rejected several earlier efforts to reintroduce the mammal. Proposals to set loose wolves and bears in Britain have also encountered resistance.
The Pleistocene-rewilding effort got its start with a 2005 paper in the journal Nature. It was roundly criticized by many scientists, who argued that reintroducing these animals could have a devastating impact on the environment. Advocates countered that the environment is worse off without the animals. Russian ecologist Sergei Zimov is already testing this notion with Pleistocene Park, an enclosed patch of frozen tundra in Siberia. He thinks reintroducing large herbivores—including wild horses and, perhaps soon, Siberian tigers—will help restore the area to grasslands. The Bialowieza forest, which straddles the border between Poland and Belarus, is the largest woodland that remains from primeval Europe. It recently reintroduced the wisent, or European bison, the biggest surviving mammal on the continent (though smaller than its American cousin). Coaxed back from the brink of extinction in the early 20th century, the wisent now numbers more than 2,000.
The debate over rewilding underscores just how arbitrary the notion of wilderness can be. In North America, the year 1492 serves a convenient baseline for what could be considered a pristine natural environment. In Europe, the line tends to be drawn near the end of the 19th century, when countries began conserving wilderness. But it can seem arbitrary, especially to people who can't fathom setting loose predators that nobody alive has ever seen in Europe's woods. "It's a bit like restoring a house that's been around for 700 years," says Simon Milne of the Scottish Wildlife Trust. "To which stage do you restore it?" The European rabbit lived only on the Iberian Peninsula until the Romans began scattering it across their empire. Should we consider it part of the wilderness?
Europe is the best place to re-create some semblance of the Pleistocene, argues Jens-Christian Svenning, a biologist at Aarhus University in Denmark. Whereas most of North America's megafauna vanished shortly after humans crossed the Bering Strait, Homo sapiens continued to coexist in Europe with the continent's largest animals, with extinctions happening over a long period. "We weren't the first human species," says Svenning. "There were Neanderthals before us, and before Neanderthals there were even more primitive human species, so there's been a long history of exposure." Lions hung on in the Balkans until the first century A.D., and the European ass, which the Portuguese called zevra, survived in Spain until the 1400s, around the same time that explorers ventured from the region into sub-Saharan Africa and passed the name on to the black-and-white zebra we know today.
Although rhinos and hippos thrived in Europe thousands of years ago, no one is sure what effect they would have on ecosystems now. "The idea of bringing back megafauna is intriguing, but when you get down to the nuts and bolts, there's a lot of questions," says Dustin Rubenstein, a biologist at the University of California, Berkeley. Species from Asia and Africa could turn out to be invasive, disturbing environments already hanging by a thread. Elephants could destroy what little forest and grassland Europe has left.
The beavers of Tierra del Fuego provide a cautionary tale. When a failed commercial fur farm released its few remaining beavers into the wild 60 years ago, the population exploded, and the critters are still wreaking havoc. Is this Britain's future? Rewilding advocates say no, the beaver will fit right in. Fiddling with nature is not a job for the meek.