AUTHOR Q & A
Why did you write this book?
When I was a kid growing up in Chicago, I used to fantasize that the mastodons whose bones lay deep under the pavement would rise out of the earth and rampage down Lake Shore Drive. Decades later, I began reporting on a group of quirky scientists who were reconstructing the lost world of the mastodon in remarkable detail-using everything from prehistoric poop to the DNA preserved in ancient fur. Most of them shared my dreams of snuffling, roaring Ice Age giants, and a few believed they could really bring that world back to life. I had to write about this.
What's the biggest surprise for most readers?
Prehistoric people seem to have helped push mammoths, mastodons, bear-sized beavers, saber-toothed cats and many other great beasts to extinction, in America and around the world. Our own species came of age in a world of giants, and as humans spread out of Africa to settle new regions, they left a trail of defunct megafauna behind them. The impact was most pronounced when people crossed into new continents. In Australia, 9-foot tall pug-faced kangaroos, a marsupial lion, and a wombat the size of a rhino vanished soon after the first people arrived, about 46,000 years ago. In the Americas the demise of great herds of native horse and camel, as well as American lions, mammoths and mastodons, coincided with the arrival of a culture of skilled Stone Age hunters about 13,000 years ago.
What discovery most surprised you as you researched the book?
Some scientists would like to bring African elephants to the Great Plains as standins for the long-lost mammoth and mastodon-and African cheetahs to replace the American version which died out 13,000 years ago. I started out thinking that advocates of "Pleistocene rewilding" were basically nuts. But as I dug deeper, I found that in some cases, introducing an animal to fill a niche left empty by an ancient extinction can really help an ecosystem. That's proved true in Australia, where the dingo, introduced by Asian sailors 4,000 years ago, now fills the vital role of top predator and protects the continent's dwindling native mammals from cats and foxes introduced by European colonists. There is a good argument to be made for Pleistocene rewilding in some situations.
What can extinct mastodons teach us about threats facing modern elephants?
The lost giants were most likely felled by a one-two punch: impacts from a growing human population that came at the same moment that climate was warming rapidly at the close of the last Ice Age. Today's elephants and other rare megafauna face the same threats, but both are greatly magnified. Humans now leave wildlife little room to move. At the same time, human-made greenhouse gases are driving a heat wave more intense than any in the evolutionary history of mammals. Understanding the demise of the mastodon may help us devise strategies to keep African elephants and rhinos, caribou, grizzly bears, and other threatened species from suffering the same fate.
What are the downsides of a world without wild megafauna?
People have always cherished great beasts because they are, to use a technical term, awesome. You can see that in the artworks at places like Chauvet and Lascaux, where Ice Age people painted and carved stunning, loving images of mammoths, wild horses, reindeer, and aurochs. So a yearning to experience these magnificent animals is not some shallow fad. I want my daughter to live in a world still twitching with lions, tigers, bears, elephants, giraffes, caribou . . . because those creatures make life more intense, beautiful, and sustainable.
In more concrete terms, megafauna shape their habitats and keep the plant and animal communities around them diverse. There are plants scattered from Mauritius to Mexico whose populations are dwindling away because there are no large wild animals available to eat and disperse their seeds. On the African savanna, elephants, zebra and other big herbivores are part of an ancient exchange between megafauna, trees, grass, and people. Elephants break up trees to eat the branches, allowing grass to grow, which later feeds zebra, wildebeest, and even domestic cattle. Here in North America, big grazers like bison increase soil fertility and improve habitat for grassland birds on the Great Plains. And recent studies of wolf and cougar ecology have shown the vital importance of big predators-without them, deer, elk and moose populations can explode, with impacts that impoverish the entire ecosystem.
Can megafauna help fight global warming?
Healthy populations of megafauna can buffer the impacts. In the Arctic, permafrost is beginning to melt as temperatures rise. Since the permafrost is packed with organic muck from the days of the mammoth, when it melts it releases vast amounts of carbon dioxide to the atmosphere. And as the environment warms, shrubs are invading the tundra, leaving the permafrost more vulnerable to melting. Big herbivores, like muskoxen and horses, can knock down shrubs and encourage the growth of grass, which insulates the permafrost.
Even domesticated cattle, tamed descendants of the extinct aurochs, can help if we handle them in the right way. Cattle kept on barren feedlots where they dine on trucked-in corn and oats have a huge carbon footprint. Cattle kept on open range, and moved from place to place to avoid over-grazing, can actually reduce the amount of greenhouse gases released from grasslands.
What do you hope readers will bring away from the book?
A new understanding of the vanished Ice Age giants, and of our own place in the world. Most scientists define megafauna as animals that weigh over 100 lbs at adulthood. So that includes people. The Earth can support only so many of us. At the close of the Ice Age, when so many kinds of giants died out, the global net weight of megafauna dropped. But then, over the next few thousand years, human populations expanded and multiplied. People and their domesticated livestock soon replaced the global biomass of the extinct giants.
When we started mining the energy from fossil fuels, that allowed our numbers and global weight to skyrocket. Humans now take up more biomass than the monsters of the Ice Age ever did. And if the system crashes, if there is another mass die-off like the one that hit 13,000 years ago, the human toll will be unimaginable. We need to understand the megafauna, because the megafauna is us.