It wasn’t a comet. Really.

A widely-held (and often-discredited) theory suggests that a comet from outer space was responsible for killing off the Clovis culture, a Paleo-Indian population living in the southwestern part of North America over 13,000 years ago. The comet theory holds that either the direct impact of the comet or the air burst it caused set the surrounding land on fire, killing all sources of food and eventually starving the remaining people there.

New research at Royal Holloway University in the U.K.—performed in conjunction with 14 other universities around the world and recently published in the journal Geophysical Monograph Series—disproves that hypothesis (again).

The project did not pinpoint an alternate explanation for the disappearance of Clovis, but the researchers have determined that a comet was definitely not to blame. If North America had been hit with something large enough to alter the Earth’s climate and wipe out a civilization, there would have been significant evidence of such an impact. But, they argue,

no appropriately sized impact craters from that time period have been discovered, and no shocked material or any other features of impact have been found in sediments. They also found that samples presented in support of the impact hypothesis were contaminated with modern material and that no physics model can support the theory.

So the comet theory is dead—really. But the problem is, for some reason it just won’t stay dead, says one researcher:

“The theory has reached zombie status,” said Professor Andrew Scott from the Department of Earth Sciences at Royal Holloway. “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.”

Hmm. Maybe the problem here is that other prevailing theories of the Clovis’ decline—for instance, that gradual changes in the animal populations of the area led the Clovis population to hunt differently and take advantage of different natural resources (that is, that the original Clovis didn’t disappear at all, their descendants merely left different artifacts behind them as time went on)—are just super boring by comparison.

Comets are way more exciting. For that reason, the Clovis Comet theory may remain forever undead.

More from Smithsonian.com:

A Comet’s Close Call

Discovered: A Prehistoric Pantry

Mammoths and Mastodons: All American Monsters