LONDON, Jan. 30 (UPI) -- An exploding comet did not end the prehistoric culture known as the Clovis people in North America 13,000 years ago as some have theorized, a study concludes.
Researchers from Royal Holloway, University of London, along with European and U.S. colleagues, say they've gathered evidence rebutting the belief a large impact or air burst caused a significant and abrupt change to the Earth's climate and terminated the Clovis culture.
Writing in the journal Geophysical Monograph Series, the researchers argue other explanations must be found for the apparent disappearance of the Clovis people.
Archaeologists have given the Clovis name to the earliest well-established human culture in the North American continent, after the town in New Mexico where stone tools were uncovered in the 1920s and 1930s.
Throwing the comet hypothesis into doubt, the researchers said no appropriately sized impact craters from that time period have ever been discovered and no material or other features usually associated with an impact have been found in sediments.
"The [comet] theory has reached zombie status," Professor Andrew Scott from the Department of Earth Sciences at Royal Holloway said. "Whenever we are able to show flaws and think it is dead, it reappears with new, equally unsatisfactory, arguments.
"Hopefully new versions of the theory will be more carefully examined before they are published."