• Email
  • Single Page
  • Print

Who Came First?

1.

Before ever a word was written, at least five thousand generations of human beings had lived out their lives on this earth, among them extraordinary innovators and adventurers who planted the first crops, created the first art, and discovered and settled entire continents. Yet except in the most extraordinary circumstances, nothing but stone tools and broken bones remain to tell us of their lives and triumphs. It is to shed light into this void that archaeologists delve into the earth, and—as one might imagine—the stories they emerge to tell are open to interpretation. Few, however, have proven as contentious as those concerning the peopling of the Americas.

The very first human discovery of the Americas must have unleashed enormous opportunity for those tribes that crossed from Asia, for at a swoop they and their descendants occupied 28 percent of the globe’s land surface—including some of its richest, most diverse, and most spectacular landscapes. Today the details of that conquest have been obscured by the mists of time, and so scientists continue to argue the basics of who, when, and how.

The traditional view is that the earliest Americans were the Clovis people, who arrived around 13,200 years ago by way of a narrow land corridor which was just then opening in the ice sheet that had long divided temperate North America from Asia. For at least thirty years, however, some archaeologists have been suggesting that the first Americans were already in residence 16,000 years ago, and that they arrived by skirting the ice barrier in boats. Their work has received much recent popular coverage, including an extended article in National Geographic magazine.1

While inherently interesting, the debate also has wider dimensions, for many traditionalists think that the Clovis were big-game hunters who exterminated America’s megafauna (including the mammoth, mastodon, and other ice-age beasts) much as hunters of the historic frontier nearly did to the buffalo. The champions of a pre-Clovis presence, on the other hand, read into bones and stones the story of a gentle people who caused no detectable environmental disturbance. Whatever the case, it is becoming clear that the debate is about even more than that, for it touches on the very way we conduct science.

J.M. Adovasio is a passionate believer in a pre-Clovis human presence in America. His book, The First Americans, which was written with the assistance of Jake Page, a former editor of Natural History magazine, presents what the authors claim to be indisputable proof that people inhabited the Americas some 16,000 years ago.

Adovasio has spent much of his professional career excavating a single site—the Meadowcroft Rockshelter in southwestern Pennsylvania—and it is this site that provides most of the evidence presented in his book. His team began work there in 1972, and over the past thirty years they have dug through eleven identifiable layers, recovered more than two million artifacts, and obtained fifty-two radiocarbon dates, using the technique by which age is established through measuring the amount of carbon-14 remaining in them.2 Consequently, Meadowcroft Rockshelter is today the litmus test for a pre-Clovis human presence in North America. If it and its sister site of Monte Verde in southern Chile (excavated by Tom Dillehay of the University of Kentucky) are invalid, the core data supporting a pre-Clovis presence in the Americas would collapse.

The First Americans commences with a long and interesting summary of speculation on the origins of the Native Americans. The extensive ancient mounds built in the Ohio River Valley and other places first piqued interest in the subject. Thomas Jefferson undertook the first scientific excavation in the history of archaeology when, in 1784, he excavated one such mound—a twelve-foot-high rise on his property near the Rivanna River, Virginia. Other early inquirers were not so rigorous. In 1839 Cornelius Mathews wrote the novel Behemoth: A Legend of the Mound-Builders, which posits that the civilization responsible for the mounds was all but destroyed by a rogue and monstrous woolly mammoth. Another fanciful nineteenth-century theory was that Noah’s Ark came to rest on the mounds. The Mormons also posit a biblical involvement, holding that the Jews came to America around 600 BC and built great cities atop the mounds, after which one group of Israelites fell from the ways of God and became red-skinned. Adovasio assures us that well into the second half of the twentieth century, Mormon missionaries were telling Native Americans and blacks that this history was proof that their skins would whiten if they joined the church. American prehistory, it seems, has often served political ends.

By the beginning of the twentieth century, rigor and professionalism were beginning to make their mark on American archaeology. William Henry Holmes, an artist turned geologist, was employed by John Wesley Powell (who was then director of both the US Geological Survey and the Smithsonian’s Bureau of Ethnology) to investigate claims of a human presence in America during the ice age. Through patient research and close observation, he was able to dismiss all such claims, thus distinguishing North America from Europe, where a considerable body of evidence of human presence during the ice age had been accumulated.

By the early 1920s it seemed to researchers that humans had entered the Americas as recently as four or five thousand years ago, but then a black cowboy made an extraordinary discovery. George McJunkin was born into slavery, and when at age fourteen he was freed by Union forces, he had not had a single day’s education. Like so many with slim prospects he decided to go west, settling on the Crowfoot Ranch in New Mexico. There he got the sons of the rancher to teach him to read, and eventually became ranch foreman, as well as a much-sought-after fiddler, surveyor, astronomer, and instrument maker.

But McJunkin’s real passion lay in the study of natural history, and he kept a small museum at his home that included fossil animal bones. One day in 1908, while out breaking wild horses, he spotted something protruding from the side of a gully. It proved to be the bone of an enormous extinct bison, and he wrote to friends telling them of the find. He returned frequently to excavate at the place, but it was not until 1926—four years after McJunkin’s death—that a team from the Colorado Museum of Natural History organized their own dig. They unearthed the near-perfect skeletons of several giant bison, and between the ribs of one lay a beautifully crafted stone spear point. This association of now-vanished giant fauna with human artifacts convinced even the most skeptical that humanity had a long pedigree in America.

A few years later, in 1933, the earlier Clovis culture was discovered. Exquisite stone spearheads, some up to twenty-three centimeters long, are its signature pieces. They were made for just three hundred years—between about 12,900 and 13,200 years ago—yet these deadly, beautiful weapons have been found across much of the US and Mexico. To me they are evocative of the deadly beauty of the Colt pistol and Winchester rifle. Just as production of these weapons coincided with the demise of the buffalo and passenger pigeon, so does the Clovis period coincide with the extinction of America’s megafauna—the mammoth, mastodon, and other ice-age giants. And the Clovis, like American frontier people, were evidently mobile, shifting their campsites frequently as they pursued their livelihoods.

Adovasio describes how he had to work with a sometimes difficult crew at Meadowcroft. Managing large field crews is never easy, for the work is tedious and unrelenting. “After twelve hours of troweling thin layers of dirt and dust, you go crazy at night,” says Adovasio. “Running, weight lifting, drinking, fornicating, staring off into space and babbling incoherently—you do almost anything for relief. It takes a truly bizarre person to live that way for months on end, and we had tents full of them.”

Adovasio says of his work, “I did not think much about my nearly fanatical drive to make Meadowcroft the best excavation ever, but I realize now with utter clarity that it was me showing [my doctoral supervisor] Jennings that I could be even better than he at his own game.” Jesse Jennings was, by Adovasio’s own account, a callous man who crushed many of those who worked with him. Adovasio called him the “Dark Lord,” and his shadow seems to have hung over his student like the influence of a saturnine father.

At the core of Adovasio’s pre-Clovis claim lie the Meadowcroft dates derived from radiocarbon analysis, which he believes are unassailable evidence. Yet only a half-dozen or so of the dates directly relate to human artifacts during the contentious 12,000–16,000 year interval, and the dating was for the most part completed before the benefits of new technology were available, including sophisticated means of purifying carbon samples, and Accelerator Mass Spectrometry, which directly counts the radioactive atoms, allowing much smaller samples to be analyzed. These tools are critical when dealing with carbon samples where contamination with material of different ages is suspected, and there have been suspicions of contamination at Meadowcroft.

Meadowcroft Rockshelter was formed in Pennsylvanian-age sandstone, which elsewhere yields the coal for which the state is famous. Some researchers have suggested that ancient coal has somehow got into the samples. But how could this have occurred? Adovasio points out that to obtain the kind of results seen at Meadowcroft, many samples would have to be contaminated in a systematic manner. There is one possible way that this could occur naturally. If groundwater carrying humic acid rose through the site, it could have deposited a gradient of contaminant through samples that already contained coal. Yet Adovasio strenuously denies that such groundwater ever existed at Meadowcroft and, prima facie, it does seem unlikely.

Of the Smithsonian-based laboratory that did most of the radiocarbon dating, Adovasio says that it was “utterly professional and almost always totally reliable.” But recent history has shown that dates produced by even the best radiocarbon laboratories are far from unassailable. Many dates processed in the 1980s and before have been reexamined using modern techniques and were found to be in error. Even worse, instances of negligence and even alleged scientific fraud have come to light, with one such spectacular case having been recently published in Science.3

Sloppy reporting may have contributed to the confusion at Meadowcroft. Dates from the lowest levels of the site—before it was occupied by humans—were processed by what Adovasio refers to as “the distinguished Oxford Radiocarbon dating facility in England,” which, he says, “explicitly stated that no indications of contamination could be found.” Dr. Richard Gillespie, the chemist responsible for preparing those samples, has been able to confirm this, but in a rather peculiar manner. It is his belief that the samples consisted entirely of coal. Thus there was “no contamination” because the entire sample was contaminant! Despite this, the report sent to Adovasio at the time identified the sample as charcoal, a porous form of carbon produced by burning wood. Gillespie believes that this mistake occurred because the sample arrived at the lab labeled as charcoal, and this was not contradicted “because of the strange British reluctance to offend, particularly [on the part of] Gowlett, the archaeologist who handled sample acquisition & sent dating reports.”4

  1. 1

    See Michael Parfit, “The Dawn of Humans: Hunt for the First Americans,” with photographs by Kenneth Garrett, National Geographic, December 2000, pp. 40–67.

  2. 2

    The following elementary explanation of the origins of radiocarbon dating is taken from the account at www.unmuseum.org/radiocar.htm:

    The time it takes for half of the atoms in a sample of radioactive material to decay into another form is known as the ‘half-life’ of the radioactive material. Different radioactive materials may have half-lives that range from a few seconds to hundreds of thousands of years.

    One naturally-occurring radioactive material found in the atmosphere is carbon-14. As plants and animals use the air, their tissues absorb some of the carbon-14. After they die, though, they no longer absorb the carbon-14 and the material in their tissues starts to decay.

    In 1949 it occurred to a scientist named Willard Libby that the amount of carbon-14 decay found in an animal or plant could be used as a gauge of how long it had been dead. Carbon-14 has a half-life of 5730 years. That meant if Libby found a sample where the amount of carbon-14 was only half the amount that might be expected in a living creature, he knew the age of it would be about 5730 years.

  3. 3

    W. Beck et al., “Ambiguities in Direct Dating of Rock Surfaces Using Radiocarbon Measurements,” Science, June 26, 1998, pp. 2132–2139.

  4. 4

    Personal communication by e-mail, March 4, 2003.

  • Email
  • Single Page
  • Print