(Reviews)

Land of the Lost

By Keith Kloor

Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America
By Paul S. Martin
University of California Press, 269 pages, $29.95

There probably aren't many conservationists who mourn the Shasta ground sloth or any of the dozens of other giant mammals that mysteriously disappeared near the end of the most recent ice age. Can you blame them? It's hard enough holding on to what's left of America's natural heritage today. So conservationists understandably focus on these extinct animals' descendants, like the bison, the grizzly bear, and the elk.

However necessary and noble these efforts are, they are “historically shortsighted and far too tame,” contends paleoecologist Paul Martin in Twilight of the Mammoths, a provocative book some will find fanciful and others visionary. Martin argues for returning the ancient beasts—sloths, saber-toothed tigers, mastodons, and other extinct megafauna—to their old stomping grounds in North America. Okay, what he really wants is to restore their evolutionary lineage by rewilding parts of the American desert and prairie with their latter-day relatives, such as the elephant and the cheetah, whose current prospects in Africa are otherwise considered dim because of poaching and habitat loss.

The idea may sound wacky, but as Martin, a professor of geosciences at the University of Arizona, points out, the fossil record supports its logic: “Before extinction of our native big mammals, the New World had much more in common with an African game park than most of us realize.” For instance, camels once roamed here, alongside the woolly mammoths and mastodons. It is these massive beasts, particularly the ground sloth, that Martin considers the hallmark animals of prehistoric North and South America. Sloths ranged from Alaska to Chilean Patagonia, with the largest of them tipping the scales at more than 13,000 pounds. In the Pleistocene Era (1.8 million years ago to 10,000 years ago), super-size mammals were the norm; there was, for example, the glyptodon, a kind of giant armadillo as big as a Volkswagen.

Today we glimpse these extinct creatures in museum dioramas, perhaps unaware that they had evolved in the Americas over millions of years. But their sudden wipeout was not unique to the continent; more than 100 large mammal species have vanished throughout the world during the past 50,000 years, a span geologists refer to as “near-time.”

Scientists attribute the die-off to climate change and overhunting by humans, whose population spread during this time frame. Martin has spent his 50-year career studying the fossil remains of the ground sloth and other lost giants, piecing together the dates of their demise. His conclusion: The sudden extinctions of large mammals tracks with the migration of hunters into new lands. In prehistoric North America, for example, the first humans are believed to have arrived about 13,000 years ago. Soon after, the ground sloths and woolly mammoths disappeared. Other scientists besides Martin also embrace the “overkill” theory, but it remains controversial because the evidence—actual kill sites—is scant.

Martin's call for “reversing prehistoric extinctions when we have the chance” is also winning prominent advocates in the field of conservation biology. The journal Nature recently carried an article signed by him and 12 other scientists (including one from the Wildlife Conservation Society and another from the U.S. Geological Survey), titled “Rewilding North America.”

Its authors propose resetting America's ecological clock to the late Pleistocene Era—not 1492, when Columbus arrived, which is the restoration benchmark used by most conservationists. Otherwise, the article warns, biodiversity will continue to decline: “The idea is to actively promote the restoration of large wild vertebrates into North America in preference to the ‘pests and weeds' (rats and dandelions) that will otherwise come to dominate the landscape.”

Twilight of the Mammoths is part ecological detective story, part polemic; in some chapters we see Martin wading through petrified ground sloth dung the size of softballs in a Grand Canyon cave. Radiocarbon analysis of the dung enables him to determine the animal's diet and life history, right up to the end of its existence. Elsewhere he explains that large new national parks or private game ranches in the United States can serve as preserves for the llama, camel, rhinoceros, and other taxonomic relatives of the extinct mammals. Public rangelands present another suitable, if highly controversial, location. Martin believes “existing ecosystems would be healthier and more balanced if they included their ‘original' complement of animal species.” Resurrecting this ancient evolutionary heritage, he also posits, would reflect true wilderness—one that predated human contact.

Martin makes a cogent, impassioned case that has the potential to reshape conservation biology practices. In essence, he contends that “ignorance of the late-Pleistocene extinctions warps our view of what ‘state of nature' we should be trying to conserve or restore.” In recent years, for example, a debate over wild horses has raged in wildlife management circles. Many conservationists argue that the horses are an alien species and that their increasing numbers are harming native ecosystems. But Martin counters that this ignores history. “Because horses evolved here, flourished for tens of millions of years, and vanished around 13,000 years ago, their arrival with the Spanish in the 1500s was a restoration, not an alien invasion,” he writes.

In the foreword to Martin's book, Cornell University biologist Harry W. Greene feels impelled to caution readers: “Realize that we are not conjuring an ancient fantasy here, that Twilight of the Mammoths is not about some furry version of Jurassic Park, only vaguely based on reality.” I second that sentiment. Twilight of the Mammoths is an engaging tale of scientific discovery that uncovers a lost part of the planet's wild, evolutionary legacy and offers some very bold ideas on how to reclaim it.

Editor's Choice

Condor: To the Brink and Back—The Life and Times of One Giant Bird
By John Nielsen
HarperCollins Publishers, 272 pages, $25.95

Pete Bloom spent several months in a shallow grave to help save a bird. Hiding in a four-foot-deep pit, he waited for Igor, the last wild California condor, to step into range of a cannon-launched net. With the push of a button, Bloom placed this endangered species' fate into human hands. John Nielsen, the longtime National Public Radio environment correspondent, fills his new book, Condor, with vivid descriptions of the dedicated people who, like Bloom, successfully brought this oversize vulture back from imminent extinction. The California condor nearly went the way of the passenger pigeon because of its allure to trophy hunters and naturalists alike—both groups wanted its skins. Additionally, collectors paid a premium price for the bird's giant, bluish-green eggs. In engaging detail, Nielsen describes how the condor also sparked a heated battle within the environmental community between those who favored a hands-off management approach (such as David Brower) and those who backed captive breeding. This ancient species thrived on the carcasses of the giant animals of prehistoric North America but dwindled as people moved into its habitat and thinned its food supply. “The condor is a relic of the Pleistocene Epoch, not quite suited to the present day and age,” writes Nielsen. “But does this mean we ought to let the condor fade away? Hell no.”

—Todd Neale

Out of Eden: An Odyssey of Ecological Invasion
By Alan Burdick
Farrar, Straus and Giroux, 324 pages, $25

Invasive species have pushed out native plants and animals all over the planet, expanded at an alarming rate, and caused billions of dollars in damages, including an estimated $138 billion a year in the United States alone. “Nature is entering a new era,” writes Alan Burdick, a senior editor at Discover magazine, “. . . wherein the greatest threat to biological diversity is no longer just bulldozers or pesticides but, in a sense, nature itself.” In the intriguing, thoroughly reported Out of Eden, Burdick follows biologists from Guam to Hawaii to San Francisco Bay, tracking brown tree snakes, wild pigs, green crabs, and other nonnative species that have decimated local ecosystems. Instead of condemning all ecological invaders as evil, Burdick seeks to demonstrate just how adaptable nature really is. “It is all too tempting to assume that an organism's ‘ecological role' is inflexibly inscribed in its biology,” he writes. “The human mind may be more niche-bound than any physical species.” People have made it that much easier for organisms to expand their ranges, hitching rides on boats, planes, and through the mail. This swarming onslaught seems beyond repair, and Burdick, while not condoning it, suggests that it is forcing us to reconsider our conventional understanding of how ecosystems function.

—Jesse Greenspan

The Republican War on Science
By Chris Mooney
Basic Books, 352 pages, $24.95

In the mid-1990s, as most of the Republican Party turned increasingly conservative and antienvironment, it began politicizing science to advance its antiregulatory agenda. Senator James Inhofe (R-OK), for example, suffered no repercussions for calling the Environmental Protection Agency a “Gestapo bureaucracy.” Lately, congressional Republicans and Bush administration officials have used euphemisms like “sound science” as a way of sugarcoating their attempts to weaken or roll back such landmark laws as the Endangered Species Act and the Clean Air Act. Conversely, they try to discredit a law or scientific finding they don't like by charging it is based on “junk science.” The result, says journalist Chris Mooney, has been to cloud issues—most notably global warming. In The Republican War on Science, Mooney also documents the party's assault on the scientific consensus on evolution, birth control, the health effects of smoking, and other hot-button topics. “These cynical slogans, ‘sound science' and ‘junk science'—reminiscent of Fox News's laughable ‘fair and balanced' mantra—have for too long masked the true intentions of a political movement whose basic mode of operation relies on the manipulation and abuse of science,” he writes. Mooney's book is a must-read for anyone who cares about restoring honest debate to some of the most pressing issues of the day.

—Todd Neale

© 2006 National Audubon Society

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