Did Woolly Mammoths Survive 7,000 Years Longer Than Expected?

Did Woolly Mammoths Survive 7,000 Years Longer Than Expected?

The last of the woolly mammoths appear to have lived on an island in the Arctic and survived for 7,000 years longer than those on the mainland.

Researchers suggested the prehistoric beasts were separated as the land masses moved around, and extinction moved more slowly on the island.

They lived on Wrangel Island, which is to the north of where Russia and Alaska come close to meeting.

Groups of the mammals on the continent contain evidence of DNA mutations as they approached extinction, but these are less apparent in the Wrangel Island fossils.

Scientists have found they were wiped out suddenly about 4,000 years ago, likely by a combination of humans arriving, extremely cold weather, and deteriorating drinking water quality.

Researchers at the University of Helsinki and Tübingen and the Russian Academy of Sciences said a combination of factors likely led to the later mammoths’ demise.

A combination of factors is believed to have sealed the ancient giants’ fate including their location on the isolated island, exposure to extreme weather events and even the introduction of prehistoric humans to the island.

Mammoths were widespread across most of the Northern hemisphere from Spain to Alaska during the last ice age, around 100,000 to 15,000 years ago.

But global warming that began 15,000 years ago saw the mammoths reign dwindle as their icy habitats of Alaska and northern Siberia shrank.

The study, published in the latest edition of Quaternary Science Reviews, detailed how a small population of mammoths, cut off from mainland Siberia and Alaska, outlived the rest of the species by 7,000 years.

It was the remnants of this long surviving population of Wrangel Island that researchers used to compare with the bones and teeth of mammoths from Northern Siberia, Alaska, the Yukon.

Scientists from Finland, Germany and Russia studied isotope compositions of carbon, nitrogen, sulfur and strontium in the mammoth bones and teeth ranging from 40,000 to 4,000 years in age.

They discovered that unlike the isotopes found in woolly mammoths from the Ukrainian-Russian plains, who went locally extinct 15,000 years ago, and the mammoths of St. Paul Island in Alaska, who died out 5,600 years ago, the composition of Wrangel Island mammoths’ collagen carbon and nitrogen isotopes did not change with the warming climate.

This suggests that they were not subject to a long-term disturbance in their diet and environment – a fact that has previously left scientists puzzled as to why the mammoths went extinct in what appear to have been favourable conditions.

A change in the DNA of Wrangel Island mammoths was also observed by another study which found mutations in the way the animals metabolised fat.

While Siberian mammoths had to rely on reserves of fat, Wrangel mammoths did not as they did not endure such harsh conditions as their predecessors.

The two populations showed differences in their carbonate carbon isotope values indicating a change in the fats and carbohydrates in the later population’s diet.

Dr Laura Arppe from the Finnish Museum of Natural History Luomus, University of Helsinki, who led the team of researchers said: ‘We think this reflects the tendency of Siberian mammoths to rely on their reserves of fat to survive through the extremely harsh ice age winters, while Wrangel mammoths, living in milder conditions, simply didn’t need to.’

Drinking water for the Wrangel Island mammoths may have been affected by the break down of bedrock as higher levels of sulfur and strontium were found in the bones of later members of the population.

With no obvious conclusion as to why the mammals went extinct so quickly researchers can only theorise the short-term events that led to their demise.

Extreme snow and ice leading to a lack of food and starvation is a likely scenario, say researchers.

Professor Hervé Bocherens from the Senckenberg Center for Human Evolution who co-wrote the study said: ‘It’s easy to imagine that the population, perhaps already weakened by genetic deterioration and drinking water quality issues could have succumbed after something like an extreme weather event.’

However scientists say they have believe human contribution may have played a part.

Human bones dating just a few hundred years were found on on Wrangle island after the extinction of mammoths, meaning it is possible the spread of humans meant a decline in mammoth numbers leading to extinction.

Isolated populations of large mammals are found to be particularly vulnerable to human behaviour and environmental factors by the study.

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