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In the summer of 1977, on a field trip in northern Patagonia, the American archaeologist Tom Dillehay made a stunning discovery. Digging by a creek in a nondescript scrubland called Monte Verde, in southern Chile, he came upon the remains of an ancient camp. A full excavation uncovered the trace wooden foundations of no fewer than 12 huts, plus one larger structure designed for tool manufacture and perhaps as an infirmary. In the large hut, Dillehay found gnawed bones, spear points, grinding tools and, hauntingly, a human footprint in the sand. The ancestral Patagonians—inhabitants of Tierra del Fuego and the Magellan Straits—had erected their domestic quarters using branches from the beech trees of a long-gone temperate forest, then covered them with the hides of vanished ice age species, including mastodons, saber-toothed cats, and giant sloths.

Fire pits indicated where the Monte Verdeans cooked their food. Grinding stones helped fashion their spear points for hunting while, scattered on the excavated floor of the large hut, Dillehay uncovered the fossilized remains of more than 20 medicinal plants, including a species of giant kelp, Durvillaea antarctica. The species was discovered in the 1830s by explorer Jules-Sébastien Dumont D’Urville, who identified the indigenous giant seaweed during the first of his three Southern Ocean voyages on the beaches of the Falkland Islands, east of Tierra del Fuego. Because seaweed is short-lived, the Durvillaea fossil provided the most precise available date for human occupation of the site. Radiocarbon analysis of charcoal, worked wooden artifacts, and the leftover bones of a mastodon meal confirmed the presence of ice age hunter-gatherers at Monte Verde 14,500 years ago, at least 1,000 years prior to any existing archaeological evidence for human colonization of the Americas, North or South.

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KELP HIGHWAY: Darwin marveled at the role that kelp played in marine ecosystems, housing a zoo of organisms that fed many others. The first Americans, dependent on marine life for survival, journeyed south along what could be called the Pacific Kelp Highway. Andrew B. Stowe / Shutterstock

During his Beagle voyage into the south Atlantic Ocean in the 1830s, Charles Darwin wondered how the Patagonians had come to venture so far south, into sub-polar cold. D’Urville’s giant kelp, it turned out, was a key to their southern passage. On the deck of the Beagle, when Darwin shook out the entangled roots of another giant kelp species ubiquitous in southern waters, Macrocystis pyrifera, he discovered a living zoo: from the microorganic coral incrustations decorating each frond to innumerable polyps, algae, mollusks, and crustacea to cuttlefish, crabs, starfish, sea eggs, crawling nereids, and schools of small fish of stunning variety. This marine banquet in turn fed the ever-present birds—the cormorants, albatrosses, and petrels that circled the Beagle—as well as otters, seals, and dolphins that crowded the bleak channels and islands of Tierra del Fuego. Contemplating this colorful menagerie, Darwin conjectured that nowhere else in the world did so many species depend for their existence on a single plant. These included the maritime peoples of Tierra del Fuego, who had adapted somehow to the sub-Antarctic cold and sustained themselves on fish and seal flesh garnished by dried tidbits of the seaweed itself. Were the keystone kelp to be destroyed, a mass extinction, including humans, would inevitably follow. Both Macrocystis pyrifera and Durvillaea antarctica were critical to the survival of the first people in the Americas. Their extinction, it turned out, had a more modern, pernicious cause.

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When modern humans migrated out of Africa around 60,000 years ago, they dispersed rapidly through Asia, and thence to Europe. Seafaring peoples hopscotched across the Pacific and reached Australia via a land bridge from Indonesia. But for tens of thousands of years, America remained terra incognita, barricaded by ice. In the 1930s, a site uncovered in New Mexico, called Clovis, suggested that early human hunters had penetrated south along an ice-free corridor no earlier than when the northern glaciers commenced their retreat 11,000 years ago. Once in the Great Plains, these first explorers discovered a rich array of megafauna—mammoths and mastodons—entirely unprepared for human aggression, and gorged themselves accordingly. It made for an arresting narrative: the first Americans were marauding big-game hunters who braved the ice and quickly established themselves as all-conquering apex predators of the New World.

The first Americans were beachcombers who followed the rich food source of kelp along the Pacific coast.

Dillehay’s discoveries at Monte Verde in Chile shattered this theory and threw American archaeology into a period of bitter turmoil. With the emergence of the Monte Verdean foragers, an entire new history of human colonization of the Americas was required. Allowing some thousands of years for these pioneers to make their way from Siberia across the Beringia land bridge to the tip of South America—adjacent to the opposite pole from where they began—necessitated a first entry date of approximately 15,000 years before present. At this time, the glaciers of the last ice age were still near their maximum, and no ice-free corridor existed through the western plains of modern Canada. That left the unglaciated Pacific coast as the only possible migratory route. Instead of butchering their way into the heartland as big-game hunters, the first Americans were beachcombers—maritime opportunists who rafted the innumerable estuarine waterways of ancient California, living off the smorgasbord of sea creatures inhabiting the so-called kelp highway of the west coast.

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Unlike the inland corridor, this marine route for the first Americans was linear, unobstructed, and entirely at sea level. Giant seaweed forests—including Durvillaea antarctica and Macrocystis pyrifera—hosted protein-rich populations of giant sea bass, cod, rockfish, sea urchins, abalones, and mussels. A now-extinct species of sea otter offered variety to the first Americans’ palate. The seaweed fragment of Durvillaea antarctica that Dillehay had found at Monte Verde signified more than an iodine-rich medicinal supplement for ancient hunter-gatherers. It was a clue to the entire history of American colonization, whereby the first humans had followed the rich food source of the kelp highway along the Pacific coast from Alaska to Chile. A rare clue, necessarily. The vast majority of the American kelp highway and its way stations—traveled when sea levels were up to a hundred meters lower than today—is now submerged beneath the Pacific Ocean.

Climate change had opened the highway south, but weather did not always cooperate with the first Americans. In fact, wild climate fluctuations of the Late Pleistocene epoch—some slingshot glaciations unfolding in the course of a human lifetime—made for a stressed, low-density community of humans who could boast of little more than heroic extreme-weather resilience. Thousands of years before D’Urville navigated the chill waters of the Straits of Magellan, the ancestral Fuegians had ventured into deep South American terrain released by rising temperatures and retreating glaciers. Monte Verde was one such frontier domain. But then, about 14,500 years ago, the climate pendulum swung back, catching the pioneers by surprise. The so-called Antarctic Cold Reversal—when average temperatures fell up to 6 degrees Celsius below present day—lasted two millennia, during which the ancient Americans huddled for survival in caves. When temperatures warmed again, the largest southern glacier outside Antarctica melted, flooding the Straits of Magellan, and cutting off the southernmost adventurers from the mainland. The cultural division of Patagonian peoples into mainland hunters and coastal canoeists—a mystery to the Victorian explorers Darwin and D’Urville—originated with this early Holocene warming 8,000 years ago.

As controversy over the new coastal migration theory raged through the 1990s, another discovery—at the polar opposite end of Earth—added to the glacial mystique of the first Americans. Near the River Yana, at 71° north, above the Arctic Circle in Siberia, Russian scientists uncovered a hunting camp some 40,000 years old. The decorated horn of an extinct rhinoceros and detachable spear shafts anticipated the Clovis peoples of North America many millennia in the future. Meanwhile, genetic analysis concluded that all modern indigenous Americans can trace their ancestry to a single community in this very region of Siberia, perhaps a mere thousand strong.

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BRIDGE TO A NEW WORLD: The first Americans were climate warriors. Their ice age journey south began with a trek over the Beringia land bridge, seen here in an animation that illustrates its geological transformation from 21,000 years ago to today.NOAA

Between Yana River and Monte Verde, transcontinental traces had now emerged of what was surely the greatest journey of all time. Over the course of 20,000 years, a small, intrepid human group somehow adapted to Arctic tundra conditions in the midst of an ice age, surviving −40 degrees Celsius temperatures without firewood in animal skin tents. No modern-day analogy exists for these climate warriors, which means we can’t honestly guess how they coped. We then lose track of the Yana people for several hundred generations before their putative descendants’ reemergence as fishermen-navigators, pushing southward along the Pacific Coast into warmer climes, all the way to modern Chile. Then the glaciers rebounded, and a small frontier group was trapped south of latitude 55° and had to adapt all over again to polar extremes.

Darwin’s question about how the Patagonians had come to inhabit the cold, wild tip of South America has been answered by the kelp highway theory. The marine cornucopia hosted by Durvillaea antarctica and Macrocystis pyrifera had lured the prehistoric Americans ever farther southward. Since then, Patagonian lifeways remained remarkably static: no leap to agriculture or cattle-rearing was possible in the sub-Antarctic landscape. But how the marooned Fuegians managed to survive the polar cold at the world’s end for thousands of years—as their Yana forebears had done north of the Arctic Circle—continues to baffle and amaze.

All modern indigenous Americans can trace their ancestry to a single community in Siberia.

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Patagonian skulls provide an incomplete answer. D’Urville’s official phrenologist, Pierre Dumoutier, failed to persuade his hosts to provide him with the craniums of dead relatives. But latter-day skull scientists—cranial morphologists—have identified cold-adaptive traits common to Fuegians and the Inuit of the Canadian Arctic. Freezing air is deadly to human lungs; hence the nostrils play a vital role in warming the breath before it bathes the tender membranes of the chest. Adapted to polar temperatures, the nasal cavities of the Fuegians and Inuit are the most capacious of all modern humans, allowing for maximum air turbulence and residence time for each inhalation. Fuegian skeletal remains nevertheless show marked evidence of temperature stress: these include chronic inflammation of bone tissue, arthritis of the back, and overworked masticating jaws, as well as osteomyelitis, in which bones become infected and “die”—all indicators of cold trauma. The Fuegians survived, but they suffered. Little wonder Patagonian oral history revolves around myths of glaciation and angry deities of freezing rain and storms.

For all the Patagonians’ epic climate resilience, however, there was no surviving the European invasion. Five years after D’Urville’s visit to the Straits of Magellan, the Chilean government sponsored its first settlements in Patagonia, setting the indigenous communities on a fast track to extinction. No biological remains exist to determine whether any other micro-evolutionary adaptations had enabled the Patagonians to endure for thousands of years south of latitude 55°. A fat-intense diet—dependent on the abundant seal population of the straits—must have been indispensable to their survival. It’s possible that the emaciated condition of the maritime Fuegians, as D’Urville encountered them, was due to the already significant inroads of the European fishing industry on Southern Ocean seal populations. One species of fur seal—the Arctocephalus gazella— had already been wiped out on the neighboring South Shetland and South Georgia islands. Their Fuegian descendants who were not killed by measles, alcohol, or guns froze to death from lack of seal meat insulation.

European awe of the Patagonians resulted from a double sense of difference. They wondered at the natives’ adaptation to the cold, while being humbled by their own intolerance for sub-Antarctic extremes. Hundreds of Spanish colonists had died of exposure and starvation in the Magellan Straits in 1583. They ate seaweed and mussels in imitation of the locals, but not enough guanaco or seal to keep out the cold. A decade later, Englishman Thomas Cavendish took the ship Roebuck into the same waters, where his men expired from “the extremity of frost and snow” at the rate of eight or nine a day. Cavendish deposited his hypothermic invalids on the beaches to die, while the remnant crew threatened mutiny from “their ardent desire of being out of the cold.”

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This physical intolerance for sub-Antarctic latitudes translated into great mental stress for all Europeans who ventured there, beginning with Magellan’s mutineers, whom the explorer felt compelled to hang, draw, and quarter on deck as an example to the rest of his men to bear the cold without complaint. Francis Drake dealt similarly with a rebel officer on his own voyage around Cape Horn. Given the option to be marooned, face trial in England, or be beheaded on the spot, the shivering gentleman chose the ax. Darwin’s discoveries in the South Atlantic created a blueprint for archaeologists to chart the amazing journey of the first Americans and map the unique kelp ecology that sustained them. But during the Beagle’s first voyage to Patagonia in 1827-28, her captain, Pringle Stokes, became so despondent at the “dreariness and utter desolation” of the Straits of Magellan that he shot himself. This was a place, he wrote in his diary of Patagonian despair, where “the soul of man dies in him.”

Gillen D’Arcy Wood is the author of Land of Wondrous Cold: The Race to Discover Antarctica and Unlock the Secrets of Its Ice. He is professor of environmental humanities at the University of Illinois, Urbana-Champaign, where he serves as associate director of the Institute for Sustainability, Energy, and the Environment. His previous book is Tambora: The Eruption That Changed the World. Originally from Australia, he lives in Urbana, Illinois, with his wife and two children.

Excerpted from Land of Wondrous Cold: The Race to Discover Antarctica and Unlock the Secrets of Its Ice, by Gillen D’Arcy Wood. Copyright © 2020 by Princeton University Press. Reprinted by permission.

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Lead image: Esteban De Armas / Shutterstock

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