Doug Peacock, author of Grizzly Years and Walking It Off, once walked point as a polar-bear guard on an Arctic expedition, armed with only a homemade spear. He still loves large predators and new territory, and in his latest outing, he asks us to accompany him on โ€œthe greatest adventureโ€ everโ€”the peopling of the New World.

Roughly 20,000 years ago, scouts on a ridge in Beringia got their first glimpse of the โ€œunending wild country that encompassed two continents uninhabited by humans.โ€ Some 5,000 years later, at the very end of the Pleistocene, the climate changed; oceans rose; and the Bering land bridge flooded. The formerly ice-barred interior of the Americas opened, allowing passage south.

โ€œI canโ€™t think of a richer, wilder, more-perilous time to live,โ€ Peacock writes.

There are parallels as well as vast differences between that time and ours, Peacock says. He is curious about how Homo sapiens perceives risk and how our species might survive and adapt to climate changeโ€”dealing with our own saber-toothed foe in the bush. The โ€œbold migrationsโ€ of the past, he concedes, are โ€œimpossible in the 21st centuryโ€ as a solution. But that original migration still offers us โ€œchallenging illustrations of courage and caution.โ€

Blending archaeology and paleontology with memories of childhood arrowhead-hunting, and evoking a keen sense of place, Peacock explores some of the colonistsโ€™ likely waypoints: Siberiaโ€™s tiger-tracked Amba River, the Yukonโ€™s Bluefish Caves (one held a mammoth bone spear point), a 13,000-year-old burial site on the Yellowstone (yielding โ€œ10 five-gallon buckets of artifactsโ€), 10,000-year-old human teeth in British Columbia, and Baja Californiaโ€™s 8,000-year-old shell middens.

The book suffers from some sloppy editing and repetition, but Peacockโ€™s accounts of archaeological finds ring with the excitement of discovery. His descriptions of dire wolves, lions on steroids, and leggy, short-faced bearsโ€”โ€monsters of the plainsโ€โ€”can raise the hairs on the back of your neck. โ€œWe evolved to deal with the predator,โ€ he writes. And therein could lie the rub: โ€œIn comparison, present day โ€˜global warmingโ€™ seems distant, harmlessly incremental or something that happens to remote strangers.โ€

Still, Peacock seems confident that a species that overcame flesh-and-blood threats like dire wolves can somehow manage to confront this latter-day, more nebulous foe.

This article originally appeared in High Country News.

In the Shadow of the Sabertooth: A Renegade Naturalist Considers Global Warming, the First Americans and the Terrible Beasts of the Pleistocene

By Douglas Peacock

AK Press

200 pages, $15