March 31, 2010

Climate Change Not The Cause Of Mammoth Extinction

The woolly mammoth died out suddenly and without a loss of genetic variation, all but ruling out climate change and inbreeding as possible causes of their extinction, according to a study published Tuesday in the Proceedings of the Royal Society B.

According to a March 30 article by Marlowe Hood of the AFP, "The culprit might have been disease, humans or a catastrophic weather event, but was almost certainly not climate change."

Furthermore, the scientists, including Anders Angerbjorn of Stockholm University, extracted mitochondrial DNA from the bones and tusks of female mammoths and analyzed them, finding out that even those creatures who survived late in the species' life span had a stable genetic diversity. In fact, the diversity had even increased slightly, meaning that inbreeding was not a serious issue.

Furthermore, previous research has shown that a colony of woolly mammoths had survived on modern day Wrangel Island, north of Siberia, as recently as 4,000 years ago. Radiocarbon dating shows that the members of the species were only active there until approximately 100 years before humans arrived on the island, making it unlikely that mankind hunted the animal into extinction.

The findings, according to the published study, suggest "that the final extinction was caused by a relatively sudden, rather than gradual, change in the mammoths' environment."

According to Hood, the researchers theorized that an event such as "a mega-storm" or "a novel bacteria or virus could have wiped out the remaining population," and that another possibility is that "expanding forests in Europe and parts of Asia robbed the grass-eating mammoths of their preferred habitat, gradually starving them to death."

The wooly mammoth (Mammuthus primigenius) is believed to have been only slightly taller than modern Asian elephants. They were between nine and 13-feet tall and weighed more than 8 tons, and are well known for their thick coat of fur. They also had curved tusks that could reach lengths of over 15-feet. The first members of the species date back approximately 150,000 years.


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