|by Stephen Oppenheimer
Shaking the 'Clovis First' orthodoxy
In spite of evidence for human activity at 19,000 years ago from Meadowcroft in North America, many American archaeologists still insist that the earliest reliably dated evidence of human habitation in North America are 11,500-year-old fluted projectile points found in Clovis, New Mexico. The distinctive points, which could be attached to a wooden spear to make a formidable weapon, became identified with small groups of people spreading slowly across North America who came to be known as the "Clovis" culture.
One of the first pieces of evidence to call the so-called "Clovis first" theory - into question was confirmation in 1997 of human habitation at a coastal site known as Monte Verde in southern Chile. Artifacts left there by early peoples predate the earliest known Clovis artifacts by 1,000 years.
CLOVIS - WHY THE CONTROVERSY?
A brief background
The most contentious issue in American archaeologyis the so-called Clovis orthodoxy or Clovis-first theory.
The argument went that humans could not have come into America before the Clovis points made their appearance because the way through was blocked by ice. All the Clovis dates pointed to a beginning that coincided with the opening of a vast corridor through the ice running from north-west to south-east from 13,000 years ago. Before this corridor opened, went the argument, no-one could have traversed the ice-sheets. Never mind that, even when it was open, the ice corridor was several thousand kilometres of barren Arctic desert and a lake requiring many packed lunches to traverse this was the grand theory into which all elements could be fitted.
The history of this orthodoxy goes back perhaps to the end of the nineteenth century, before which time it was a heresy. In the 1890s William Henry Holmes of the Smithsonian Institution’s Bureau of American Ethnology and Thomas Chamberlin of the United States Geological Survey chased off many dubious claims for Pleistocene (ice-age) occupation of the New World. The mantle of authority for this gatekeeper role was passed in the 1920s to the physical anthropologist Ales Hrdlicka, also of the Smithsonian. Long after, in 1995, Hrdlicka was singled out by American author Vine Deloria in his book Red Earth, White Lies as a heavy-handed zealous defender of the academic status quo who quashed research proposals designed to explore alternative theories.
In 1926, Jesse Higgins of the Colorado Museum of Natural History found a pointed stone artefact at a site near Folsom, New Mexico, which also yielded the skeleton of an extinct bison. Hrdlicka refused to accept this as evidence of Pleistocene human occupation since no archaeologist had checked the association with the bones before the point was removed. Another stone point was found in 1927. It was left on site, examined, photographed, and verified by outside experts. Higgins found more and larger points, with the same fluting (fluting is where flakes have been struck from the base, presumably to facilitate hafting), first in 1932 in Colorado, in association with mammoth skeletons, then five years later, again with mammoth bones at Clovis, New Mexico. These larger points, now known as Clovis points, lay beneath representatives of the other type, now known as Folsom points, which were associated with bison skeletons.
Thus was it ‘proved’, by the criteria of the time, that humans had entered the New World before 10,000 years ago. The old theory, of a more recent colonization, was overturned, and ‘the rest is history’ as far as many American archaeologists are concerned. But all was not quite as it should be in a nicely rounded drama. In the cycle of theories, this was the ‘good guy’ phase: authoritative dogma overturned by careful observation and persistence after frustration and denigration. In due course, the wheel would turn.
Subsequently, Clovis points were turned up throughout the continental United States. The conviction grew among American archaeologists that these stone tools were the signature of the first human colonization of the Americas. After all, surely these first explorers were expert Upper Palaeolithic big-game hunters who had followed the mammoth trail across Beringia from Asia in the waning years of the last glaciation?
In 1964, American geochronologist C. Vance Haynes collected and linked together the dates of various Clovis-point sites using the new technology of carbon dating. These dates bracketed the earliest Clovis points to 11,00011,500 years ago, and none was more than 12,000 years old. This latter age was significant for geologists, since they believed this was after the time when a corridor opened up between the two great melting ice sheets of North America and allowed passage from Alaska through Canada to the rest of the Americas (about 12,00013,000 years ago). These two ice sheets, the Laurentide lying over Hudson Bay to the east and the Cordilleran covering the Rockies to the west, were so large that, on the evidence available in the 1960s, they seemed to span the continent.
The Clovis-first theory had now matured into a complete and established orthodoxy. The architects of the theory now became its high priests, and the theory was ripe for the next phase in the cycle of attack and defence of the new status quo. That attack and the fierce defence have now lasted over thirty years.
The strength, and at the same time the chief weakness, of the Clovis-first theory was that the earliest Clovis point had to be just after the opening of the ice corridor, and the ice corridor had to be just before the earliest Clovis point. Like a house of cards, nudge a key structural element and it will fall down. The key element was the insistence on the dates limiting the earliest entry to the Americas to after the opening of the ice corridor. If the occupation of North or South America could be pushed back just a few thousand years to a time when the corridor would have been closed, the theory would fall. In that case, the first entry would have to have been much earlier before the Last Glacial Maximum (LGM), and probably before 22,000 years ago.
Pretenders, heretics, or scientists?
Seen in this light, new pretenders bearing dates more than 1,500 years before Clovis would in effect be suggesting entry to the Americas before the ice age rather than after, a radically new theory. Although it would be marginally less persuasive, any evidence of occupation in South America, even slightly before Clovis and with different adaptive technology, would also make it unlikely that Clovis points identified the entry of the first Americans.
There have been plenty of new pretenders over the past few decades, whether we are talking about new archaeological sites with pre-Clovis evidence, or their advocates. In one review from 1990 I counted eighteen contender sites. This is a conservative estimate, perhaps half, of the total challenges mounted over the past two decades. Most of these pretenders have been routed by defenders of the Clovis-first orthodoxy in skirmishes characterized by attacks on scientific method, context, and observation. Only a few have survived the ‘critical’ broadsides fired by defenders of the orthodoxy, but they are still embattled. The most persistent and serious pretenders are the sites of Monte Verde in northern Chile and Meadowcroft Rockshelter in south-western Pennsylvania New recruits have joined their ranks, namely Cactus Hill in Virginia and Topper/Big Pine in South Carolina.
The history of these claims and refutations is revealing of academe.
The weapons of argument used by the defenders certainly appeal to scientific method, careful observation, avoidance of known sources of error, balanced logic, and reason; but the tactics of appeal are clearly biased, selective, petty, personal, and confrontational. In other words, the method of defensive attack is ‘sling enough mud in the form of possible errors or what if’s, and the good evidence all becomes tarred with the bad and can be dismissed’. This is reminiscent of a stock courtroom drama, where the witness is discredited by the clever, aggressive lawyer. That is, however, an adversarial, not a scientific approach. Furthermore, unlike the judge, archaeologists are not required to come to closure of a case or theory. They can and should remain open to different interpretations of the evidence. The ‘truth’ whatever it is is not on trial. Clovis-first and its defenders, however, may well be.
There is no particular a priori reason to think that America was first colonized after the last ice age rather than before, since sealocked Australia, New Guinea, and even the Bismarck Archipelago and the North Solomon Islands were all colonized well before the LGM. On the other hand, there is every reason to assume that evidence is generally clearer the more recently it was set down, and that the global effects of the ice age destroyed much good evidence in North America. The fact, therefore, that there are a lot of Clovis points lying around from a few thousand years after the LGM, in good context, as opposed to the less well-provenanced evidence from before the LGM, does not prove that Clovis was first. It merely disproves the preceding orthodoxy of the nineteenth century, that America was not colonized until 10,000 years ago. We should expect the preglacial evidence (if any) that questions Clovis-first to be weaker than Clovis itself.