No Evidence for Clovis Comet Catastrophe

New research challenges the controversial theory that an ancient comet impact devastated the Clovis people, one of the earliest known cultures to inhabit North America.

Writing in the October issue of Current Anthropology, archaeologists Vance Holliday (University of Arizona) and David Meltzer (Southern Methodist University) argue that there is nothing in the archaeological record to suggest an abrupt collapse of Clovis populations. "Whether or not the proposed extraterrestrial impact occurred is a matter for empirical testing in the geological record," the researchers write. "Insofar as concerns the archaeological record, an extraterrestrial impact is an unnecessary solution for an archaeological problem that does not exist."

The comet theory first emerged in 2007 when a team of scientists announced evidence of a large extraterrestrial impact that occurred about 12,900 years ago. The impact was said to have caused a sudden cooling of the North American climate, killing off mammoths and other megafauna. It could also explain the apparent disappearance of the Clovis people, whose characteristic spear points vanish from the archaeological record shortly after the supposed impact.

As evidence for the rapid Clovis depopulation, comet theorists point out that very few Clovis archaeological sites show evidence of human occupation after the Clovis. At the few sites that do, Clovis and post-Clovis artifacts are separated by archaeologically sterile layers of sediments, indicating a time gap between the civilizations. In fact, comet theorists argue, there seems to be a dead zone in the human archaeological record in North America beginning with the comet impact and lasting about 500 years.

But Holliday and Meltzer dispute those claims. They argue that a lack of later human occupation at Clovis sites is no reason to assume a population collapse. "Single-occupation Paleoindian sites — Clovis or post-Clovis — are the norm," Holliday said. That’s because many Paleoindian sites are hunting kill sites, and it would be highly unlikely for kills to be made repeatedly in the exact same spot.

"So there is nothing surprising about a Clovis occupation with no other Paleoindian zone above it, and it is no reason to infer a disaster," Holliday said.

In addition, Holliday and Meltzer compiled radiocarbon dates of 44 archaeological sites from across the U.S. and found no evidence of a post-comet gap. "Chronological gaps appear in the sequence only if one ignores standard deviations (a statistically inappropriate procedure), and doing so creates gaps not just around [12,900 years ago] but also at many later points in time," they write.

Sterile layers separating occupation zones at some sites are easily explained by shifting settlement patterns and local geological processes, the researchers say. The separation should not be taken as evidence of an actual time gap between Clovis and post-Clovis cultures.

Holliday and Meltzer believe that the disappearance of Clovis spear points is more likely the result of a cultural choice rather than a population collapse. "There is no compelling data to indicate that North American Paleoindians had to cope with or were affected by a catastrophe, extraterrestrial or otherwise, in the terminal Pleistocene," they conclude.

History of Clovis people:

The Clovis culture is a prehistoric Native American culture that first appears in the archaeological record of North America around 13,500 years ago, at the end of the last ice age.

The culture is named for artifacts found near Clovis, New Mexico, where the first evidence of this tool complex was excavated in 1932. Earlier evidence included a mammoth skeleton with a spear-point in its ribs, found by a cowboy in 1926 near Folsom, New Mexico. Clovis sites have since been identified throughout all of the contiguous United States, as well as Mexico and Central America.

The Clovis people, also known as Paleo-Indians, are generally regarded as the the first human inhabitants of the New World, and ancestors of all the indigenous cultures of North and South America. However, this view has been recently contested by various archaeological finds which are claimed to be much older.

There are a number of controversial sites vying for the position of the earliest site in the region. The best evidence, however, suggests that a society of hunters and gatherers known as Clovis People were the first to settle in the Southwest, probably sometime before 9,500 B.C. The Clovis People were so named after the New Mexico town, site of the first discovery in 1932, near Clovis, N.M.

Since the mid 20th century, the standard theory among archaeologists has been that the Clovis people were the first inhabitants of the Americas. The primary support of the theory was that no solid evidence of pre-Clovis human inhabitation has been found. According to the standard accepted theory, the Clovis people crossed the Beringia land bridge over the Bering Strait from Siberia to Alaska during the period of lowered sea levels during the ice age, then made their way southward through an ice-free corridor east of the Rocky Mountains in present-day western Canada as the glaciers retreated.

The culture lasted for about a half a millennium, from about 11,200 to 10,900 years ago. People of the Clovis culture were successful, efficient big-game hunters and foragers. Judging from sites on the North American Great Plains, the Clovis people were skilled hunters of huge animals, especially Ice Age mammoths and mastodons.

It is generally accepted that Clovis people hunted mammoth: sites abound where Clovis points are found mixed in with mammoth remains. Whether they drove the mammoth to extinction via overhunting them – the so-called Pleistocene overkill hypothesis – is still an open, and controversial, question, keeping in mind that Archaeology is purely a theoretical endeavor.