New study challenges Clovis comet catastrophe theory

The controversial theory that an ancient comet impact devastated the Clovis people, one of the earliest known cultures to inhabit North America, has been challenged by new research.

Archaeologists Vance Holliday (University of Arizona) and David Meltzer (Southern Methodist University) argued that there is nothing in the archaeological record to suggest an abrupt collapse of Clovis populations.

"An extra-terrestrial impact is an unnecessary solution for an archaeological problem that does not exist," the researchers wrote.

The comet theory first emerged in 2007 when a team of scientists announced evidence of a large extra-terrestrial 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 mega fauna.

It could also explain the apparent disappearance of the Clovis people, whose characteristic spear points vanished from the archaeological record shortly after the supposed impact.

As evidence for the rapid Clovis depopulation, comet theorists pointed out that very few Clovis archaeological sites showed evidence of human occupation after the Clovis.

At the few sites that do, Clovis and post-Clovis artefacts are separated by archaeologically sterile layers of sediments, indicating a time gap between the civilisations.

In fact, comet theorists argued, 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 disputed those claims. They argued that a lack of human occupation at Clovis sites is no reason to assume a population collapse.

In addition, they compiled radiocarbon dates of 44 archaeological sites from the US and found no evidence of a post-comet gap.

Shifting settlement patterns and local geological processes easily explained sterile layers separating occupation zones at some sites, the researchers said.

The separation should not be taken as evidence of an actual time gap between Clovis and post-Clovis cultures.

The resrachers believed 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 Paleo-Indians had to cope with or were affected by a catastrophe, extraterrestrial or otherwise, in the terminal Pleistocene era," they concluded.

The report has been published in the October issue of Current Anthropology.