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Ice Age: New Findings and Theories.

 
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ramonmercadoOffline
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PostPosted: 03-05-2006 14:56    Post subject: Ice Age: New Findings and Theories. Reply with quote

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Ice Age Horses May Have Been Killed Off by Humans, Study Finds
Brian Handwerk
for National Geographic News

May 1, 2006
Some 12,000 years ago, North American mammoths, ancient horses, and many other large mammals vanished within the short span of perhaps 400 years.

Scientists cannot be sure what killed them, but a new study suggests that humans aren't off the hook just yet.




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The large animals' disappearance at the end of the Pleistocene era (50,000 to 10,000 years ago) happened at about the same time that many large animals, or megafauna, went extinct around the globe.

Victims included species such as the saber-toothed cat and the diprotodon—a rhinolike beast that was the world's largest marsupial.

Now a new study of the fossil record fuels the debate about the cause of the creatures' fate.

In North America two major events occurred at about the same time as the megafaunal extinctions: The planet cooled, and early humans arrived from Asia to populate the continent.

For decades scientists have debated which of these factors was responsible for widespread megafaunal extinctions.

Was the climate change simply too much for the animals to withstand? Or did the ancient mammals succumb to human hunting pressure?

Many experts suggest a combination of these factors and perhaps others, such as disease.

"It's hard to see this as one of those things where a single piece of evidence will make it obvious what happened," said Scott Wing, a paleobiologist at the Smithsonian Institution's National Museum of Natural History.

"The phenomenon that people are trying to explain is not something that happened in one place at one time. It happened across the globe, at different times on different continents. I think that there are clearly multiple factors involved."

Humans Not Exonerated

Previous research had suggested that Alaska's caballoid horse species became extinct some 500 years before the first humans arrived.

Those dates would mean that overhunting could not have contributed to the extinction of Alaska's ancient horses—though humans could have contributed to the demise of North American mammoths, which stayed on the scene for perhaps another thousand years.




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But Andrew Solow, a geostatistician at Woods Hole Oceanographic Institution in Massachusetts, and colleagues have published a statistical evaluation of the fossil record that suggests that humans shouldn't be exonerated just yet.

Their data, to be published in tomorrow's issue of the journal Proceedings of the National Academy of Sciences, reveal that horses did disappear before mammoths, though only by perhaps 200 years.

Their findings also suggest that both species may not have gone extinct until after human arrival—so human hunting may well have played a role in their demise.

"You can't just take the latest fossil remains [and assign their date] as the time of extinction," Solow said. "There's a sampling issue.

"We constructed a confidence region—that's the set of dates that you can't rule out with confidence as the extinction times."

Those dates suggested the possibility that both caballoid horses and mammoths survived well past the generally accepted arrival dates for humans.

The results don't identify the cause of the extinctions, and experts say a fossilized "smoking gun" seems unlikely.

"Even if a fossil told you that [species] survived past the arrival of humans, it's still the case that there was climate change going on as well as hunting pressure," Solow said.

"I think the notion that there was a single cause is probably not right. It's probably more complicated than that."

The Smithsonian's Wing believes that the complicated circumstances leave paleobiologists and others with their work cut out for them to determine just why so many of the world's large animals vanished.

"I think that leaves everyone with a big job to do to investigate new sites, date remains, date human occupations, and try to do the best that they can," he said.

"It may take a long time to accumulate enough evidence. But this is the kind of thing that has to happen."

Ice Age


Edit to amend title.


Last edited by ramonmercado on 26-08-2010 11:57; edited 1 time in total
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PeniGOffline
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PostPosted: 03-05-2006 22:08    Post subject: Reply with quote

Okay, as stupid and misleading headlines go, that one's more annoying than amusing. And I'm afraid the reportage is of the sort that gives people an entirely wrong impression of the field.

Since we don't know when humans arrived in North America; since we don't understand the mechanisms of mass extinction; and since we don't have more than the vaguest notion of the timing of the late Pleistocene megafaunal extinctions - of course we can't rule humans out as a factor. But we can't exactly find ourselves guilty, either!

This sort of slow, incremental work to gather the data that will eventually make hypotheses such as Overkill testable (though in its original form Overkill has already been falsified and I wish people'd get over it) isn't dramatic, but it's very important, and I wish reporters would discuss that angle instead of pretending there's a revelation hidden in here somewhere. Actually I don't suppose the reporter wrote the headline, so maybe I shouldn't be too hard on him.

Okay, rant over; now to look at the bright side.

It encourages me that someone is focusing on horses, because from the point of view of understanding megafaunal extinction they are extremely interesting. Item: Horses evolved in North America. Item: When horses were reintroduced to North America in historic times, they succeeded very well indeed, establishing a large and viable feral popularion so fast it makes your head spin. Item: At the time of megafaunal extinction, mammoths went extinct in Eurasia and horses did not. Item: At the time of megafaunal extinction, the grassland habitat which horses love so well was (so far as current data indicates) expanding at the expense of less horse-friendly habitats like forest and tundra. Item: As megafauna go, horses are more comparable to more species than charismatic mondomegafauna like the mammoth and the ground sloth.

Put it all together and, if we can figure out what happened to horses, we've got a good chance of figuring out what happened to the others, too. Camelids are another interesting species - they went extinct only in North America, and an attempted historic reintroduction did not pan out.
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ramonmercadoOffline
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PostPosted: 04-05-2006 09:46    Post subject: Reply with quote

i guess i could have changed the headline, but it was NGs. they usually are more careful about these things. an interesting article and certainly food foe thought (puts on nosebag).
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PostPosted: 04-05-2006 10:36    Post subject: Reply with quote

V. interesting. PeniG's reply took most of my rant...so, if you'll excuse me...me too (lazy)...hmm, perhaps other megafauna were lazy...damn, written my own extinction obit Laughing
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ramonmercadoOffline
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PostPosted: 26-08-2010 11:58    Post subject: Reply with quote

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Ice Age remains found during A46 widening work
http://www.bbc.co.uk/news/uk-england-nottinghamshire-11094111

A46 dig Ice Age artefacts along with Roman remains have been uncovered

Archaeological remains from the Ice Age have been uncovered by workmen widening the A46 in Nottinghamshire.

Flint tools dating back to 11,000BC were discovered at Farndon during work to turn the road into a dual carriageway.

The stretch from Newark to Widmerpool has already revealed a Roman road and fragments of Roman pottery.

More than 100 archaeologists have worked to ensure important remains have been properly recorded and recovered.

Geoff Bethel, A46 Highways Agency project manager, said: "As the A46 follows the route of the old Roman road, we expected to uncover a number of artefacts from Roman Britain and we were not disappointed; but to uncover such rare flint tools dating back to the end of the Ice Age was very exciting."

The Department for Transport is spending more than £340m improving the A46 between Newark and Widmerpool.

The 17-mile (28km) stretch is designed provide a new, fast link between the A1 and M1.
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ramonmercadoOffline
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PostPosted: 03-04-2011 13:09    Post subject: Reply with quote

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Creswell Crags cave art site gets cash boost
http://www.bbc.co.uk/news/uk-england-12938363

Creswell Crags The caves are in cliffs which run for hundreds of metres along a gorge
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* Caves on world heritage shortlist
* Bid to preserve prehistoric site
* Ice Age cave art site preserved

Ice Age cave art site Creswell Crags is to be given a £38,000 boost from Derbyshire County Council.

The prehistoric attraction on the border of Nottinghamshire and Derbyshire has also been nominated as a World Heritage Site.

Creswell Crags, a series of limestone caves occupied between 50,000 and 10,000 years ago, has produced numerous tools and unique rock art.

A site spokesman said the money will be used to help run its visitor centre.

The site is recognised as an important European place of cultural, archaeological and scientific interest.
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