Clovis culture had a distinctive set of tools: scrapers, spear-straighteners, hatchetlike choppers, crescent-moon-shaped objects whose function remains unknown. Its hallmark was the “Clovis point,” a four-inch spearhead with a slightly cut-in, concave tail; in silhouette, the points somewhat resemble those goldfish-shaped cocktail crackers. Folsom points, by contrast, are smaller and finer—perhaps two inches long and an eighth of an inch thick—and usually have a less prominent tail. Both types have wide, shallow grooves or channels called “flutes” cut into the two faces of the head. The user apparently laid the tip of the spear shaft in the flute and twisted hide or sinew repeatedly around the assembly to hold it together. When the point broke, inevitable with stone tools, the head could be loosened and slid forward on the shaft, letting the user chip a new point. A paleo-Indian innovation, this type of fluting exists only in the Americas.
With Blackwater Draw as a pattern, scientists knew exactly what to look for. During the next few decades, they discovered more than eighty large paleo-Indian sites throughout the United States, Mexico, and southern Canada. All of them had either Folsom or Clovis points, which convinced many archaeologists that the Clovis people, the earlier of the two, must have been the original Americans.
Nobody really knew how old the Clovis people were, though, because geological strata can’t be dated precisely. Figgins surmised that Folsom had been inhabited fifteen to twenty thousand years ago, which meant that Clovis must be a little before that. More precise dates did not come in until the 1950s, when Willard F. Libby, a chemist at the University of Chicago, invented carbon dating.
Clovis (left) and Folsom points (shown to scale; fluting at bases)
(Illustration Credit 5.4)
Libby’s research began in the global scientific race during the 1930s and 1940s to understand cosmic rays, the mysterious, ultrahigh velocity subatomic particles that continually rain onto the earth from outer space. Like so many bullets, the particles slam into air molecules in the upper atmosphere, knocking off fragments that in turn strike other air molecules. Along the way, Libby realized, the cascade of interactions creates a trickle of carbon-14 (C14), a mildly radioactive form of carbon that over time disintegrates—decays, as scientists say—into a form of nitrogen. Libby determined that the rate at which cosmic rays create C14 is roughly equal to the rate at which it decays. As a result, a small but steady percentage of the carbon in air, sea, and land consists of C14. Plants take in C14 through photosynthesis, herbivores take it in from the plants, and carnivores take it in from them. In consequence, every living cell has a consistent, low level of C14—they are all very slightly radioactive, a phenomenon that Libby first observed empirically.
When people, plants, and animals die, they stop assimilating C14. The C14 already inside their bodies continues to decay, and as a result the percentage of C14 in the dead steadily drops. The rate of decline is known precisely; every 5,730 years, half of the C14 atoms in nonliving substances become regular carbon atoms. By comparing the C14 level in bones and wooden implements to the normal level in living tissues, Libby reasoned, scientists should be able to determine the age of these objects with unheard-of precision. It was as if every living creature had an invisible radioactive clock in its cells.
In 1949 Libby and a collaborator ascertained the C14 level in, among other things, a mummy coffin, a piece of Hittite floor, an Egyptian pharaoh’s funerary boat, and the tomb of Sneferu of Meydum, the first Fourth Dynasty pharaoh. Archaeologists already knew their dates of construction, usually from written records; the scientists wanted to compare their estimates to the known dates. Even though Libby and his collaborator were still learning how to measure C14, their estimates were rarely more than a century off—a level of agreement, they wrote dryly, that was “seen to be satisfactory.”
Libby won a well-deserved Nobel Prize in 1960. By that time, carbon dating was already revolutionizing archaeology. “You read books and find statements that such and such a society or archaeological site is 20,000 years old,” he remarked. “We learned rather abruptly that these numbers, these ancient ages, are not known.” Archaeologists had been making inferences from limited, indirect data. With radiocarbon, these numbers, these ancient ages, could be known, and with ever-increasing accuracy.
One of the first tasks assigned to the new technique was determining the age of the Clovis culture. Much of the work occurred at the University of Arizona, in Tucson, which in 1958 established the world’s first major archaeological carbon-dating laboratory. At the new lab was a doctoral student named C. Vance Haynes. Haynes was a mining engineer who became fascinated by archaeology during a stint in the air force. While serving at a base in the Southwest, he began collecting arrowheads, a hobby that ultimately led to his abandoning geology and coming to the University of Arizona as a graduate student in archaeology. As the Clovis-culture dates crossed his lab bench, Haynes was struck by their consistency. No matter what the location of a site, carbon dating showed that it was occupied between 13,500 and 12,900 years ago.* To Haynes, with his geologist’s training, the dates were auspicious. The Clovis culture arose just after the only time period in which migration from Siberia seemed to have been possible.
C. Vance Haynes
(Illustration Credit 5.5)
During the Ice Ages so much of the world’s water was frozen into glaciers that sea levels fell as much as four hundred feet. The strait between Siberia’s Chukotsky Peninsula and Alaska’s Seward Peninsula is now only 56 miles wide and about 120 feet deep, shallower than many lakes. The decline in sea levels let the two peninsulas join up. What had been a frigid expanse of whale habitat became a flat stretch of countryside more than a thousand miles wide. Beringia, as this land is called, was surprisingly temperate, sometimes even warmer than it is today; masses of low flowers covered it every spring. The relative salubriousness of the climate may seem incredible, given that Beringia is on the Arctic Circle and the world was still in the throes of the Ice Ages, but many lines of evidence suggest that it is true. In Siberia and Alaska, for instance, paleoentomologists—scientists who study ancient insects—have discovered in late-Pleistocene sediments fossil beetles and weevils of species that live only in places where summer temperatures reach the fifties.
Beringia was easily traversable. Western Canada was not, because it was buried beneath two massive, conjoined ice sheets, each thousands of feet deep and two thousand miles long. Even today, crossing a vast, splintered wilderness of ice would be a risky task requiring special vehicles and a big support staff. For whole bands to walk across it with backpacks full of supplies would be effectively impossible. (In any case, why would they want to do it?)
There was a short period, though, when the barrier could be avoided—or at least some scientists so believed. The Ice Ages drew to a close about fifteen thousand years ago. As the climate warmed, the glaciers slowly melted and sea levels rose; within three thousand years, Beringia had again disappeared beneath the waves. In the 1950s some geologists concluded that between the beginning of the temperature rise and the resubmergence of the land bridge the inland edges of the two great ice sheets in western Canada shrank, forming a comparatively hospitable pathway between them. This ice-free corridor ran down the Yukon River Valley and along the eastern side of the Canadian Rockies. Even as the Pacific advanced upon Beringia, these geologists said, plant and animal life recolonized the ice-free corridor. And it did so just in time to let paleo-Indians through.
In a crisply argued paper in Science in 1964, Haynes drew attention to the correlation between the birth of “an ice-free, trans-Canadian corridor” and the “abrupt appearance of Clovis artifacts some 700 years later.” Thirteen thousand to fourteen thousand years ago, he suggested, a window in time opened. During this interval—and, for all practical purposes, only during this interval—paleo-Indians could have crossed Beringia, slipped through the ice-free corridor, and descended into southern Alberta, from where they would have been able to spread throughout North Ame
rica. The implication was that every Indian society in the hemisphere was descended from Clovis. The people at Blackwater Draw were the ancestral culture of the Americas.
Haynes was the first to put together this picture. The reaction, he told me, was “pretty gratifying.” The fractious archaeological community embraced his ideas with rare unanimity; they rapidly became the standard model for the peopling of the Americas. On the popular level, Haynes’s scenario made so much intuitive sense that it rapidly leapt from the pages of Science to high school history textbooks, mine among them. Three years later, in 1967, the picture was augmented with overkill.
If time travelers from today were to visit North America in the late Pleistocene, they would see in the forests and plains an impossible bestiary of lumbering mastodon, armored rhinos, great dire wolves, sabertooth cats, and ten-foot-long glyptodonts like enormous armadillos. Beavers the size of armchairs; turtles that weighed almost as much as cars; sloths able to reach tree branches twenty feet high; huge, flightless, predatory birds like rapacious ostriches—the tally of Pleistocene monsters is long and alluring.
(Map credit 5.1)
At about the time of Clovis—between 13,800 and 11,400 years ago, according to a 2009 study—almost every one of these species vanished. So complete was the disaster that many of today’s big American mammals, such as caribou, moose, and brown bear, are immigrants from Asia. The die-off happened amazingly fast—the statistics, according to the study, suggest that it was instantaneous. And when it was complete, naturalist Alfred Russell Wallace wrote, the Americas had become “a zoologically impoverished world, from which all of the hugest, and fiercest, and strangest forms [had] recently disappeared.”
The extinctions permanently changed American landscapes and American history. Before the Pleistocene, the Americas had three species of horse and at least two camels that might have been ridden; other mammals could have been domesticated for meat and milk. Had they survived, the consequences would have been huge. Not only would domesticated animals have changed Indian societies, they might have created new zoonotic diseases. Absent the extinctions, the encounter between Europe and the Americas might have been equally deadly for both sides—a world in which both hemispheres experienced catastrophic depopulation.
Researchers had previously noted the temporal coincidence between the paleo-Indians’ arrival and the mass extinction, but they didn’t believe that small bands of hunters could wreak such ecological havoc. Paul Martin, a paleontologist who was one of Haynes’s Arizona colleagues, thought otherwise. Extinction, he claimed, was the nigh-inevitable outcome when beasts with no exposure to Homo sapiens suddenly encountered “a new and thoroughly superior predator, a hunter who preferred killing and persisted in killing animals as long as they were available.”
Imagine, Martin said, that an original group of a hundred hunters crossed over Beringia and down the ice-free corridor. Historical records show that frontier populations can increase at astonishing rates; in the early nineteenth century, the annual U.S. birthrate climbed as high as 5 percent. If the first paleo-Indians doubled in number every 20 years (a birthrate of 3.4 percent), the population would hit 10 million in only 340 years, a blink of an eye in geological terms. A million paleo-Indians, Martin argued, could easily form a wave of hunters that would radiate out from the southern end of the ice-free corridor, turning the continent into an abattoir. Even with conservative assumptions about the rate of paleo-Indian expansion, the destructive front would reach the Gulf of Mexico in three to five centuries. Within a thousand years it would strike Tierra del Fuego. In the archaeological record, Martin pointed out, this hurricane of slaughter would be visible only as the near-simultaneous appearance of Clovis artifacts throughout North America—and “the swift extermination of the more conspicuous native American large mammals.” Which, in fact, is exactly what one sees.
Not everyone was convinced by Martin’s model. Paleontologists noted that many non-game species vanished, too, which in their view suggests that the extinction wave was more likely due to the abrupt climatic changes at the end of the Pleistocene; Martin pointed out that previous millennia had experienced equally wild shifts with no extinction spasm. In addition, similar extinctions occurred when human beings first invaded Madagascar, Australia, New Zealand, and the Polynesian Islands.
Despite overkill’s failure to enjoy full acceptance, it helped set in stone what became the paradigmatic image of the first Americans. Highly mobile, scattered in small bands, carnivorous to a fault, the paleo-Indians conjured by archaeologists were, above all, “stout-hearted, daring, and voracious big-game hunters,” in the skeptical summary of Norman Easton, an anthropologist at Yukon College, in Whitehorse. Clovis people were thought to have a special yen for mammoth: great ambulatory meat lockers. Sometimes they herded the hairy creatures en masse into gullies or entangling bogs, driving the animals to their doom with shouts, dogs, torches, and, possibly, shamanic incantations. More often, though, hunters stalked individual beasts until they were close enough to throw a spear in the gut. “Then you just follow them around for a day or two until they keel over from blood loss or infection,” Charles Kay, an ecological archaeologist at Utah State University, told me. “It’s not what we think of as sporting, but it’s very effective and a hell of a lot safer than hand-to-hand combat with a mammoth.”
Shifting location to follow game, the Clovis people prowled roughly circular territories that could have been two hundred miles in diameter (the size would vary depending on the environmental setting). With any luck, the territory would contain flint, jasper, or chalcedony, the raw material for spear points, meat scrapers, and other hunting tools. Bands may have had as many as fifty members, with girls going outside the group to marry. At camp, women and girls made clothes, gathered food—wild plums, blackberries, grapes—and tended babies. Men and boys went hunting, possibly as a group of fathers and sons, probably for days at a time.
As the extinctions proceeded, the Clovis people switched from mammoths to the smaller, more numerous bison. The spear points grew smaller, the hunting more systematic (with prey becoming scarcer, it needed to be). Bands camped on ridges overlooking ponds—the men wanted to spot herds when they came to drink. When the animals plunged their muzzles into the water, hunting parties attacked, forcing the startled bison to flee into a dead-end gully. The beasts bellowed in confusion and pain as the paleo-Indians moved in with jabbing spears. Sometimes they slaughtered a dozen or more at once. Each hunter may have gobbled down as much as ten pounds of bison flesh a day. They came back staggering under the load of meat. Life in this vision of early America was hard but pleasant; in most ways, archaeologists said, it was not that different from life elsewhere on the planet at the time.
Except that it may not have been like that at all.
CONTINENTAL DIVIDE
In the early 1980s a magazine asked me to report on a long-running legal battle over Pacific Northwest salmon. A coalition of Indian tribes had taken Washington State to court over a treaty it had signed with them in 1854, when the state was still part of the Oregon Territory. In the treaty, the territory promised to respect the Indians’ “right of taking fish, at all usual and accustomed grounds and stations,” which the tribes interpreted as guaranteeing them a share of the annual salmon harvests. Washington State said that the treaty did not mean what the Indians claimed, and in any case that circumstances had changed too much for it still to be binding. The courts repeatedly endorsed the Indian view and the state repeatedly appealed, twice reaching the U.S. Supreme Court. As the Indians approached final victory, tension rose in the fishing industry, then almost entirely controlled by whites. The magazine wanted me to write about the fight.
To learn more about the dispute, I visited the delta of the Nisqually River, at the southern tip of Puget Sound. Housing the Nisqually tribe, the sliver of land that is their reservation, and the riverbank meadow on which the treaty was signed, the delta is passed through, unnoticed, every day by the thousands of co
mmuters on the interstate highway that slices through the reservation. At the time of my visit, the Nisqually had been annoying state authorities for decades, tenaciously pursuing what they believed to be their right to fish on their ancestral fishing grounds. I met the Franks, the stubborn, charismatic father-and-son team who then more or less ran the tribe, in a cluttered office that in my recollection occupied half of a double-wide trailer. Both had been arrested many times for “protest fishing”—fishing when the state said they couldn’t—and were the guiding spirits behind the litigation. After we spoke, Billy Frank, the son, told me I should visit Medicine Creek, where the Nisqually and eight other tribes had negotiated the treaty. And he asked someone who was hanging around to give me a tour.
That someone introduced himself as Denny. He was slim and stylish with very long black hair that fell unbound over the shoulders of his Levi jacket. Sewn on the back of the jacket was a replica of the American eagle on the dollar bill. A degree in semiotics was not required to see that I was in the presence of an ironist. He was not a Nisqually, he said, but from another Northwest group—at this remove, I can’t recall which. We clambered into an old truck with scraped side panels. As we set off, Denny asked, “Are you an archaeologist?”
Journalist, I told him.
“Good,” he said, slamming the truck into gear.
Because journalists rarely meet with such enthusiasm, I guessed—correctly—that his approval referred to my non-archaeological status. In this way I learned that archaeologists have aroused the ire of some Native American activists.