Did an Exploding Comet Doom Early Americans?

New Scientist outlines a new theory on the demise of the Clovis people in the southwest US over 10,000 years ago. A group of 25 researchers speculates that a comet exploded over ice-covered Canada 12,900 years ago and triggered a firestorm across North America that not only wiped out the Clovis people but also forced a number of large land mammals into extinciton and kicked off the Younger Dryas climate change. However, geologists are pretty conservative folks, according to the article, and some of them are not buying it.

What about the firestorm?

[Podcaster]

a comet exploded over ice-covered Canada 12,900 years ago and triggered a firestorm across North America

According to TFA, the firestorm seems to be the most controversial part of their claims. All the dissenting voices in the article made mention of it.

According to the abstracts [agu.org] of the research, it looks like the strongest evidence of a trans-american firestorm is "... a carbon-rich black layer commonly referred to as a black mat, with a basal age of approximately 12.9 ka, ... identified at over 50 sites across North America"

-P

Re:Reflected across the world

[Eideewt]

Do you pretend to RTFA?

The idea is that the comet started fires that wiped out these people. They would not have affected the rest of the globe hugely due to the interfering presence of oceans. Although you would expect the smoke of a burning continent to have an effect.

According to TFA, the suggested impact happened at a time when "35 genera of the continent's mammals went extinct". Would that count as "seeing it in the ground?"

Re:Reflected across the world

[Anonymous Coward]

then surely we'd see a reduction in population across the globe due to dust blocking out the sun and such

Maybe you're thinking of the results of a supervolcano? A comet that creates a firestorm that kills/chases off a group of people won't necessarily equate to planet-wide consequences. Strip a large enough area of much of its vegetation (doesn't even have to be all or even most vegetation) and you can kill off lots of animals and people who depend on that vegetation for shelter and food.

Problem

[KwKSilver]

Clovis peoples did not "go extinct." They spread put across the Americas and developed in to more locally adapted cultures. The Folsom point is a fairly obvious derivative of the Clovis point see here [texasbeyondhistory.net]. The Folsom point supplanted Clovis on the Lower Great Plains. From Missouri to the Atlantic coast the Dalton point is considered a direct outgrowth of Clovis, and on the western Gulf Coast, the San Patrice point seems to have filled the same role as the successor to Clovis. Aside from that, there is a lot of regional variation in Clovis itself prior to the emergence of Folsom, San Patrice etc.

The Pleistocene megafauna did go extinct, but the causes of that have been argued back and forth since I was a student in the 1970s, and with no end in sight. Some have blamed Clovis and closely related groups in the Americas, and refer to these extinctions as the result of a Clovis "blitzkrieg." However, there's also evidence to suggest that some were headed down the drain before humans reached the Americas. Late Pleistocene environments were drastically different from today. The southwest was fairly moist, not a desert at all. The southeast was considerably drier than now and had fine-grained, micro-environments quite unlike anything seen today. All of those environments changed drastically, and the intricately intermingled mico-ecologies of the southeast disappeared, and any fauna dependent on that was toast (my 2 cents, there).

Re:Problem

[Inexile2002]

There is some indirect evidence that the Clovis culture died out even if some of the Folsom people were ancestors of the Clovis people. You say that the Folsom point is derivative of the Clovis point when most sources that compare the two note that the Folsom point was inferior to the Clovis. The vast majority of Folsom points were found using rock quarried from relatively local sources, where as the Clovis points are often found thousands of kilometers from the rock quarries that the stone originated from. Clovis peoples valued higher quality stone enough that they either traveled or engaged in VERY long distance trade to get it. They produced some of the most sophisticated stone tools ever developed by human beings, only really being surpassed by Pre-Colombian native Americans almost ten thousand years later. Finally, Clovis points with nearly identical workmanship have been found from Alberta to California to Patagonia and as far east as Floria - points that have been dated to within hundreds of years of years of each other. All of this indicates a sophisticated, wide ranging, traveling culture.

The Folsom people by contrast didn't leave evidence of this type of wide ranging travel and sophistication, a change that seems to have happened quite quickly. Archaeologists have speculated that climate change led to conditions that were more hostile to longer distance travel - forcing them to use lower quality stone and thus simpler stone work techniques, but the evidence does seem to indicate the death of the Clovis culture (if not the people themselves). The true reasons for the sudden culture change will probably never be known. If there's good evidence of a Pliestocine comet explosion then it almost definitely was a nail in the coffin of the Clovis peoples.

Re:Geologists are indeed conservative.

[jlehtira]

Weathermen can't accurately predict the weather a few hours out ... what makes anyone think they can predict the temperature years or decades out?

The weather a few hours out is about the distribution of mass and energy in our atmosphere.

The temperature decades out is about the total amount of mass and energy in our atmosphere.

You've got to admit that the latter is a much easier problem.