Monday, December 14, 2009

NorAm Megafauna Held Out For Past 13k Years Ago

Woolly mammoths and prehistoric horses grazed on the North American plains for several thousand years longer than hitherto assumed

This is shown by samples of ancient DNA, analysed by an international team of research scientists under the leadership of Professor Eske Willerslev from Copenhagen University. Analyses of ancient DNA thereby once again revoke results of more common methods of dating, such as carbon 14 analysis of bone and tooth remains from extinct animals. These methods which had previously dated the extinction of mammoths and prehistoric horses in Central Asia to within 13-15,000 years ago. But with the DNA-test methods of Eske Willerslev and his colleagues, this boundary has now moved between 2,600 and 5,600 years closer to our time and has thus revised our previous opinion of when the last mammoths and prehistoric horses grazed on the North American Plains.

The ancient DNA that formed the basis for this sensational result, was discovered by scientists in samples of soil from the permafrost tundra surrounding the windswept town of Stevens Village on the bank of the Yukon River in Central Alaska.

Professor Eske Willerslev says about his discovery:

"In principle, one can take a pinch of soil and uncover which living creatures, animals and plants lived in the area half a million years back in time. With ancient DNA analysis, we are completely independent of skeletons, bones, teeth and other macro-fossil evidence from extinct animals. This greatly increases the possibility of finding evidence of the existence of a species through time. Whilst an animal leaves only a single corpse when it dies, it leaves quantities of DNA traces through urine and faeces whilst it is still alive. It is these DNA traces which we find in the soil."

When the remains of the last member of an extinct species were hard to find, Willerslev and a team of international research scientists decided to carry out an expedition to Central Alaska to solve the riddle of "The last surviving mammoths" using ancient-DNA tests from permafrost soil.

Surprisingly, the scientists found that the later samples with mammoth DNA could be dated back to between 10,500 and 7,500 years ago, and are therefore between 2,600 and 5,600 years after the supposed extinction of the mammoths from mainland Alaska. Thus, the scientists found proof that mammoths had walked the earth several thousand years longer than previously believed; presumably by lesser herds of these animals threatened with extinction, surviving in small, isolated enclaves, where living conditions were intact.


DNA extraction from soil. Interesting. They draw some conclusions about the extinction that may not be right, but...it does knock the comet impact something hard.

2 comments:

Anonymous said...

The idea that a handful of the North American megafauna (particularly mastodons and mammoths, but short-faced bears, dire wolves, and, yes, horses have also been suggested) is not exactly a new one. Its been known for quite a while that mammoths and mastodons managed to survive for a while past the rest of the megafauna, perhaps as you said due to isolated populations living in areas inhabitable to humans. There has been a suggestion that a similar population of Columbian Mammoths hid out near Moab for a couple thousand years past the extinction, but I don't know if this has met with widespread acceptance.

Will Baird said...

There have been mammoth and mastodon finds that were almost into the Upper Holocene (5 to 6k years ago). They are sometimes regarded as questionable though.