When it comes to explaining why the woolly mammoths died out, “death from above” could be down for the count.
Nearly 13,000 years ago, North American megafauna like the mammoths and giant sloths—and even human groups like the people of the Clovis culture—disappeared as the climate entered a cold snap. As DISCOVER has noted before, there’s been a controversial hypothesis bubbling up saying that a comet impact caused it all, but other scientists have been shooting holes in that idea of the last couple years. In a study in this week’s Proceedings of the National Academy of Sciences, a team led by Tyrone Daulton pooh-poohs what may be the last major evidence that supports the impact idea.
That evidence takes the shape of nano-diamonds in ancient sediment layers, a material said to form during impacts only.
These 12,900-year-old sediments were claimed to hold exotic materials: tiny spheres, ultra-small specks of diamond — called nanodiamond — and amounts of the rare element iridium that are too high to have occurred naturally on Earth. [BBC News]
Impact proponents published their own studies last year in Science and PNAS that set forth the nano-diamond argument. But when Daulton and company searched the sediment and examined it under transmission electron microscopes, they couldn’t find any.
“I’m convinced there’s no [hexagonal] diamond present,” says Daulton. Instead, the group unearthed aggregates of sheetlike forms of carbon. “If you don’t look too closely at it, you could convince yourself it is [hexagonal diamond],” says Daulton. “Theirs was a gross misidentification.” [ScienceNOW]
Unsurprisingly, the impact-backing scientists didn’t care for the assertion that they talked themselves into seeing diamonds.
The lead author of two earlier comet-impact papers, Douglas Kennett, an archaeologist at the University of Oregon in Eugene, calls the study “fundamentally flawed science”. “The claim we misidentified diamonds is false, misleading and incorrect,” he adds, although he declined to specify his objections. [Nature]
However, he did promise to write PNAS with his objections and to point out errors he says are in Daulton’s work.
Related Content:
80beats: Nano-Diamond Discovery Suggests a Comet Impact Killed the Mammoths
80beats: Spores in Mastodon Dung Suggest Humans Didn’t Kill Off Ancient Mammals
80beats: The Last Mammoths Made a Round Trip Across the Bering Land Bridge
DISCOVER: Were the First Americans Wiped Out By an Asteroid?
Image: Wikimedia Commons / Tracy O
August 31st, 2010 at 4:38 pm
Lol, it would be nice if there were one or two extinct animals in recent history we weren’t responsible for. Oh well.
August 31st, 2010 at 5:07 pm
Cool Picture!
August 31st, 2010 at 5:31 pm
Humans have a genetic need to deny the function of space rock impacts, which is to periodically cleanse the Earth of accumulated infections. We see this in constant assertions that the dinosaurs were wiped out by volcanoes or climate change. Behind the denial is subliminal awareness that we are next, we could not evolve a society dedicated to fighting rocks, so we die by rocks – and simple minded cartoon cheerfulized zombies just bury their heads in the sand. Like the way the whole tribe censors and suppresses Rock Prophecy, the answers are all there, but the sheeple follow the evil media leader to conceal it all. Try to look up Rock Prophecy online – whole divisions of the Pentagon, NASA and Microsoft are dedicated to sabotaging access to that website. When some browsers do get thru it’s only because untold numbers of enslaved I.T. defectors risk imprisonment in Gitmo to lift the web’s Iron Curtain long enough to let us to see forbidden fruit. Whatever life evolves here next will use Rock Prophecy as the New World Religion that informs of ways NOT to stage a civilization. It’s all a dominator conspiracy, get used to it. EMBRACE YER EXTINCTION SHEEPLE.
September 1st, 2010 at 8:38 am
@ProphetJimi –
Man, that’s some rant. Quite poetic, too.
And for all I know, you might be right. Who can tell, before time and study clarify such matters?
On a more serious note, this story sums up the tension in modern science between truth and sensationalism. We are storytelling animals. The true facts may be more or less interesting than the marvelous story we can tell from the facts, and many good scholars can get caught in the riptide.
I agree with those whose see the Earth’s biosphere extending, through physical and metaphysical interactions, deep into the Solar System. Evolutionary biology and archaeology cannot be fully mapped, as it were, without accounting for mass and energy inputs from exoplanetary sources. Pulses of cometary debris, interplanetary plasma discharges, poorly-understood field interactions between the Sun and its planets, and other infrequent phenomena all likely shaped our ancestors’ lives.
September 1st, 2010 at 8:50 am
@ #3
“Humans have a genetic need to deny the function of space rock impacts, which is to periodically cleanse the Earth of accumulated infections.”
You almost make it sound like uncleanliness causes the rocks to hit us. Kinda like a magnet, huh?
I like the rest of it, even though it’s unsubstantiated.
September 1st, 2010 at 1:06 pm
Humans don’t deny that exoplanet impacts have occurred that cause mass extinction. It is widely accepted that 65 million years ago such an event occurred wiping out most of the dinosaurs. Most scientists, who are generally human, also state that such impacts have happened often in the earth’s past and will happen again in the future. Hence why NASA and other space agencies are trying to track large asteroids and other objects that may hit our little blue home.
What scientists REFUSE to say, and with good reason, is that the impact events were part of some master plan of a great diety or some far away superior life force to rid the planet of its ‘accumulated infections’. There is a pattern to these events but the reasons why they have occurred on such a regular frequency has not been properly explained. To think any different would be folly.
September 1st, 2010 at 4:34 pm
“Most scientists, who are generally human,”…..ha! like that! Hey- can we leave the “deity” junk out of a scientific discussion please? The One don’t care about this teeny tiny speck of solar dust, or its arrogant self centered infection. What science in general needs is Wisdom…..and that only comes when one can honestly say to the world at large “I Don’t Know.”
Being able to admit ignorance is truly the first step toward accepting there are things we will never know, and probably shouldn’t try.
September 1st, 2010 at 7:42 pm
Another argument supports a comet collision:
Lamb 1977 reported a Global Climatic Boundary at 2760 BP. The Younger Dryas cold period began 12,679 BP and by subtracting the radio carbon 2760 BP date provides the nominal 9919 years (supposedly two Vulcan orbital revolutions. Vulcan’s theoretical period computed by this web site 4969.0 years is two times this value is = 9938 +/- 11.5 years (one sigma error) compared to the 9919 +/- 32 year value from the comet induced weather change data. The impacts are thought to come from the B:Cl-2. See:
http://www.barry.warmkessel.com/SimplyPut.html
http://www.barry.warmkessel.com/4related.html#a2
September 2nd, 2010 at 2:48 pm
I can’t wait for January of 2013 when the Mayan calendar has passed and the extintion prophecy junkies are forced to either create another happening for us to be concerned with or simply put down the pipes/tabs/crystals and attempt to think rationally.
August 2nd, 2011 at 8:49 am
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