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Humans to Blame for Ice Age Extinctions, Study Says
National Geographic ^ | August 10, 2005 | Hillery Mayell

Posted on 08/11/2005 11:02:22 AM PDT by ZULU

Humans are likely responsible for the extinction of Ice Age megafauna—large mammals like giant sloths, short-faced bears, mammoths, and saber-toothed cats—that occurred in the Americas around 11,000 years ago, a new study says.

Scientists have long debated whether giant pre-historic mammals disappeared because of climate change or because humans hunted them to extinction.

The mass extinctions coincided with both the end of the last Ice Age and the arrival of humans in the Americas around 11,000 years ago. This timing has made it difficult for scientists to isolate the cause of the species' disappearance.

But a study comparing the extinction of giant ground sloths in North and South America with the disappearance of their smaller relatives in West Indian islands has helped clear up the picture, scientists say.

The researchers say archaeological and fossil evidence strongly suggests that ancient hunters pushed the animals to extinction.

Giant ground sloths "cruised through" at least 22 major climate cycles as the continental ice sheets in North America advanced and retreated over the last two million years, said David Steadman, a paleobiologist at the University of Florida.

Steadman is a co-author of the new study published in the Proceedings of the National Academy of Sciences.

"The only thing that's different [at the end of the Ice Age] is the arrival of people," he said.

Giant Sloth: A Case Study

Until about 11,000 years ago, at least 19 different sloth species lived in North and South America in a variety of ecosystems. Only a few small, tree-dwelling sloth species survive today.

Steadman and his colleagues argue that if ecosystem shifts resulting from climate change caused the sloths' demise, then all extinctions—on both islands and the mainland—should have taken place at the same time, as the last Ice Age ended between 15,000 to 9,000 years ago.

Radiocarbon dates of bones, dung, and other tissue of extinct sloths place their last appearance in North America at around 11,000 years ago and at about 10,500 years ago in South America, Steadman says.

But on the islands of Cuba and Hispaniola—shared today by modern-day Haiti and the Dominican Republic—sloths survived until about 4,400 years ago.

Their subsequent extinction coincided exactly with the arrival of the first humans on the islands, Steadman says.

"What [this study] shows us is that there's this great big suggestive pattern that we find: Wherever human beings first appear all around the world, these large mammals pretty quickly become extinct," said Gary Haynes, an archaeologist at the University of Nevada at Reno, who was not involved in the study.

"[Some] people will say that you have to [establish the cause of extinction] species by species, and I think they're probably right," Haynes added. "But the study does create a good model that might make us think that if it worked for one big animal it's probably what we'll find for other big animals."

Overkill Vs. Climate Change

Steadman and his colleagues argue that megafauna species on the American continents, having evolved in an environment without humans, may have been particularly vulnerable to the sudden appearance of big game hunters.

The 5,000-pound (2,300-kilogram) giant ground sloth is a case in point. In addition to having no fear of humans, it was the size of a modern-day elephant, it couldn't hide, and as it name implies, it moved very slowly.

"Walking up to a ground sloth and trying to spear it to death probably wasn't one of the most macho things they [early hunters] did," Steadman said. "Any hunter could outrun one."

But other scientists maintain that climate change was the driving force in Ice Age extinctions. They argue that the retreat of ice sheets from North America caused a major change in habitat that the giant mammals couldn't adapt to.

At the peak of the Ice Age around 20,000 years ago, the ice covered much of North America.

As the sheets melted between 18,000 and 8,000 years ago, warmer temperatures and shifting rainfall patterns forced plants and animals to move out of old habitats and into new ones.

Proponents of the climate-change theory add that there's little evidence that humans hunted anything other than mammoths. Yet species like wild horses, camels, and saber-toothed cats all went extinct at about the same time.

"There are no archaeological sites for species other than mammoths, and perhaps mastodons, where you find a spear sticking out of an animal, and everyone agrees that there is evidence of human hunting," Nevada's Haynes said.

"So the lack of kill sites doesn't bother me," he added. "There's a real lack of a 'smoking gun' implicating either climate change or human hunting, but that's true for every theory."

Climate change may have been a factor in pushing the animals to extinction, Steadman says, but it took humans to push them over the edge.

"Animals like the ground sloth, which had a poor ability to regulate body temperature, should have thrived in a warmer climate," he said.


TOPICS: Culture/Society
KEYWORDS: bushsfault; catastrophism; culinaryarts; godsgravesglyphs; history; moronscience; powerfuldelusion; revisionistscience
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Burp!!!
1 posted on 08/11/2005 11:02:23 AM PDT by ZULU
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To: ZULU

Oh, I feel sooo guilty. I think I'll go outside and hug a tree.


2 posted on 08/11/2005 11:03:59 AM PDT by conservatrice
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Yeah, all 20 of us that were alive at that time sure did throw a lot of parties.


3 posted on 08/11/2005 11:04:42 AM PDT by TOWER
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To: ZULU

Clearly this is all Bush's fault.


4 posted on 08/11/2005 11:06:01 AM PDT by COEXERJ145 (Tom Tancredo- The Republican Party's Very Own Cynthia McKinney.)
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To: ZULU

"All Bush's fault."


5 posted on 08/11/2005 11:06:23 AM PDT by Designer (Just a nit-pick'n and chagrin'n)
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To: ZULU

Yeah, It's Bush's fault.


6 posted on 08/11/2005 11:06:27 AM PDT by gate2wire (We Honor Those Who Serve---WE REMEMBER--Thank you)
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To: ZULU
PETA is demanding reparations!
7 posted on 08/11/2005 11:06:48 AM PDT by Apercu ("Res ipsa loquitor")
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To: ZULU
The mass extinctions coincided with both the end of the last Ice Age and the arrival of humans in the Americas around 11,000 years ago. This timing has made it difficult for scientists to isolate the cause of the species' disappearance
8 posted on 08/11/2005 11:07:11 AM PDT by konaice
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To: ZULU

Rovian plot!


9 posted on 08/11/2005 11:07:37 AM PDT by threeleftsmakearight
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To: COEXERJ145

His name wasn't Bush back then, it was Thud.


10 posted on 08/11/2005 11:08:16 AM PDT by Extremely Extreme Extremist
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To: ZULU
I blame Atook Bush the cave dweller.
11 posted on 08/11/2005 11:08:35 AM PDT by BallyBill (Laughing at Liberals, it's not just for breakfast anymore!!)
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To: ZULU

I just figured it was one human's fault.....Where was George Bush?


12 posted on 08/11/2005 11:09:49 AM PDT by When do we get liberated?
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To: ZULU

> Humans are likely responsible ... he mass extinctions
> coincided with both the end of the last Ice Age and
> the arrival of humans in the Americas ...

So, not just any "humans", but Native Americans.

They need to trot out that old environmental ad featuring
the chief with a tear rolling down his cheek, with a new
voice-over saying: "Oops. Sorry."


13 posted on 08/11/2005 11:10:01 AM PDT by Boundless
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To: ZULU

Here we have 'scientists' gazing into their crystal balls again.


14 posted on 08/11/2005 11:10:44 AM PDT by MEGoody (Ye shall know the truth, and the truth shall make you free.)
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To: ZULU
"Walking up to a ground sloth and trying to spear it to death probably wasn't one of the most macho things they [early hunters] did," Steadman said. "Any hunter could outrun one."

Which just goes to prove...........

PETA = People Eating Tasty Animals!
Click the Pic J

15 posted on 08/11/2005 11:11:05 AM PDT by Fiddlstix (This Tagline for sale. (Presented by TagLines R US))
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To: conservatrice
I think I'll go outside and hug a tree.

OK.

bzzzzzzzz.

But not that one.

bzzzzzzzz.

NOT THAT ONE!

bzzzzzzzz.

Crack!

Whoosh!

Oh, sorry - Hope it didn't fall on you...

16 posted on 08/11/2005 11:12:12 AM PDT by Izzy Dunne (Hello, I'm a TAGLINE virus. Please help me spread by copying me into YOUR tag line.)
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To: ZULU

So what? We're part of nature aren't we? We evolved from dirt, just like the rest of the animal kingdom. We can do anything we dang well please, then.


17 posted on 08/11/2005 11:14:22 AM PDT by Brilliant
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To: ZULU

No way. Grizzly bears and polar bears ate them all.


18 posted on 08/11/2005 11:15:16 AM PDT by microgood
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To: ZULU

There's no way it could've been a giant flood </sarc>


19 posted on 08/11/2005 11:15:35 AM PDT by Manic_Episode (OUT OF ORDER)
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To: ZULU
ancient hunters pushed the animals to extinction.

I'm a good shot, what do you want from me, eh? I'm a good shot.

20 posted on 08/11/2005 11:16:07 AM PDT by dead (I've got my eye out for Mullah Omar.)
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To: ZULU

"Humans to Blame for Ice Age Extinctions, Study Says"
There is a typo here Humans should read BUSH to Blame


21 posted on 08/11/2005 11:16:19 AM PDT by DM1
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To: ZULU

They were so greedy and primitive back then. They used to order slabs of ribs so huge that they would literally tip their cars over.


22 posted on 08/11/2005 11:16:25 AM PDT by Jaysun (Democrats: We must become more effective at fooling people.)
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To: ZULU

They couldn't believe they ate the whole thing!


23 posted on 08/11/2005 11:16:49 AM PDT by mewzilla (Property must be secured or liberty cannot exist. John Adams)
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To: ZULU

Or rather, the slots evolved into...Democrats!


24 posted on 08/11/2005 11:16:52 AM PDT by kx9088
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To: ZULU

Damn that Fred Flintstone and his rock-wheeled SUV!!!


25 posted on 08/11/2005 11:17:04 AM PDT by Looking4Truth (Never trust the old media for information.)
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To: ZULU
Hold on one cottin' pickin' minute! You say that 11,000 years ago there was an Ice Age? So that means the Earth has been warming since then?

Wow, and here I thought if it weren't for us humans, the earth would go merrily along in pristine perfection for all eternity.

26 posted on 08/11/2005 11:17:08 AM PDT by Yo-Yo
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To: ZULU

Without a video I don't think I'll "choose" to believe this story.


27 posted on 08/11/2005 11:17:43 AM PDT by Mister Baredog ((Minuteman at heart, couch potato in reality))
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To: ZULU
"There's a real lack of a 'smoking gun' implicating either climate change or human hunting, but that's true for every theory."

What is not a theory is that scientists have too much time on their hands coming up with more and more theories. Until they present facts their theories belong in comic books.

28 posted on 08/11/2005 11:18:12 AM PDT by taxesareforever (Government is running amuck)
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To: ZULU

Wasn't Helen Thomas a young girl back then?


29 posted on 08/11/2005 11:18:16 AM PDT by Night Hides Not (The only NOC list containing the name of Valerie Plame was stolen by Ethan Hunt.)
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To: Manic_Episode
There's no way it could've been a giant flood

One that engulfed North American and Canada 11,000 years ago and took 7000 more years to get to Cuba and Hispaniola.

Well, I suppose it could have been a flood of molasses.

30 posted on 08/11/2005 11:19:18 AM PDT by Right Wing Professor (Proudly neocon since 1982!)
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Giant ground sloth - it's what's for dinner!


31 posted on 08/11/2005 11:20:59 AM PDT by vollmond (Careful with that axe, Eugene!)
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To: ZULU
Wait just a minute! There is no way this could be true!

The only humans in the Americas at that time were Indians, uh, sorry, Siberian-Americans, who we all know lived in peace and harmony with their surroundings and were perfect stewards of the environment. (Of course they did cultivate a little of that awful weed for smoking - tobacco.)

They couldn't possibly have caused thye extinction of any species. It has to be evil European white males who are responsible for this travesty. (Maybe the Vikings got here earlier than anybody thought.)

32 posted on 08/11/2005 11:21:09 AM PDT by rmh47 (Go Kats! - Got Seven? [NRA Life Member])
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To: ZULU

Wooly Mammoth... the "other white meat".


33 posted on 08/11/2005 11:21:26 AM PDT by taxed2death (A few billion here, a few trillion there...we're all friends right?)
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To: ZULU
There is dccumented video to support this claim. The Flintstones always orders Dino-Ribs and Bronto-Burgers!

Talk about slothful behavior!!!

34 posted on 08/11/2005 11:21:59 AM PDT by Young Werther
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To: ZULU

No wonder the Vulcans didn't think we were ready for space exploration and the Klingons and Romulans hated us so much.


35 posted on 08/11/2005 11:22:20 AM PDT by VRWCmember
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To: Boundless
So, not just any "humans", but Native Americans.

Needless to say, the professional acitivsts among them hate this theory. See, they were a peaceful people living in harmony with their environment, before Whitey came.

The fact is, the biggest ecological disaster for Australia was the arrival of the aborigines; the biggest for New Zealand was the arrival of the Maoris; the biggest for Hawaii the arrival of the Native Hawaiians. By the time Europeans arrived here and to those places, there wasn't a whole lot left to despoil.

36 posted on 08/11/2005 11:23:10 AM PDT by Right Wing Professor (Proudly neocon since 1982!)
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To: Yo-Yo
the Earth has been warming since then?

Yep. Global Warming started right when humans appeared, nasty little CO2 breathers that we are.
37 posted on 08/11/2005 11:24:36 AM PDT by Famishus (Ted Kennedy's car has killed more people than my gun.)
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To: Right Wing Professor

> The fact is, the biggest ecological disaster for
> Australia ... New Zealand ... Hawaii ...

And we won't even bring up Easter Island prior to whitey.


38 posted on 08/11/2005 11:26:00 AM PDT by Boundless
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To: Boundless
And we won't even bring up Easter Island prior to whitey.

Don't. It's ugly. You've read 'Collapse'?

39 posted on 08/11/2005 11:27:17 AM PDT by Right Wing Professor (Proudly neocon since 1982!)
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To: rmh47

Exactly.

I demand restitution from the American Indians for killing the Mastadon!

. . . around the high plains of West Texas/Panhandle (e.g., near Canyon is one example), you can still find huge piles of bones where the Indians would repeatedly drive entire herds of buffalo off the cliffs . . .

Such a sensitive group of folks.


40 posted on 08/11/2005 11:27:23 AM PDT by MeanWestTexan
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To: Boundless
And we won't even bring up Easter Island prior to whitey.

Don't. It's ugly. You've read 'Collapse'?

41 posted on 08/11/2005 11:27:23 AM PDT by Right Wing Professor (Proudly neocon since 1982!)
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To: Right Wing Professor

42 posted on 08/11/2005 11:27:48 AM PDT by mewzilla (Property must be secured or liberty cannot exist. John Adams)
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To: ZULU

I wonder whether these "native americans" had the chance to read Al Gore's book on global warming.

Certainly, they ended the ice age, what with their campfires and methane farts from eating so much mammoth fur, so early man must have been responsible for the early global warming.


43 posted on 08/11/2005 11:28:10 AM PDT by aShepard
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To: mewzilla
ROFL!

Good thing they weren't smart enough to develop insecticides...er, I guess those would have been 'homicides'.

44 posted on 08/11/2005 11:30:15 AM PDT by Right Wing Professor (Proudly neocon since 1982!)
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To: ZULU
The mass extinctions coincided with both the end of the last Ice Age and the arrival of humans in the Americas around 11,000 years ago. This timing has made it difficult for scientists to isolate the cause of the species' disappearance.

Another huge embarrassment for National Geographic coming...

Remember when they "proved" that we were all descended from one African female? Cornrows and all? I'm sure they's rather not talk about it.
They had it nailed beyond any challenge whatsoever.
And they were 100% wrong.

45 posted on 08/11/2005 11:30:18 AM PDT by Publius6961 (Liberal level playing field: If the Islamics win we are their slaves..if we win they are our equals.)
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To: ZULU

Bushstone's Fault!!


46 posted on 08/11/2005 11:31:16 AM PDT by hispanarepublicana (There will be no bad talk or loud talk in this place. CB Stubblefield.)
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To: Right Wing Professor
Good thing they weren't smart enough to develop insecticides...er, I guess those would have been 'homicides'.

LOL!! I can just see it now. Okay, who's got the Cro Magnon repellent?

47 posted on 08/11/2005 11:32:50 AM PDT by mewzilla (Property must be secured or liberty cannot exist. John Adams)
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To: ZULU

Is it wrong that the most upsetting part of this whole thing (to me) is that I'll never get to know what giant sloth or wooly mammoth taste like with Stubbs BBQ sauce?


48 posted on 08/11/2005 11:33:02 AM PDT by leoncaruthers
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To: ZULU

If only PETA had been around 11,000 years ago, then no doubt the woolly mammoths would still be here today.


49 posted on 08/11/2005 11:34:24 AM PDT by jpl
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To: ZULU

It was Bush's great-great-great-great-grandparents fault!


50 posted on 08/11/2005 11:35:57 AM PDT by Stark_GOP
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