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Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ As the last woolly mammoths met their deaths on a remote Arctic island

As the last woolly mammoths met their deaths on a remote Arctic island



Mammoth tooth found on Wrangel Island.
Image: Juha Karhu

The last mammoths to hail on Earth lived on the Wrangel Island in the Arctic Ocean. This segregated population lived thousands of years after most of the mammoths left, but when the extinction finally came, it happened quickly. New evidence can finally explain what happened to these stubborn hobbies.

Studies published in Quaternary scientific reviews shed new light on the latest population of woolly mammoths and possible causes for their extinction.

Chemical analysis shows that the mammoth habitat on Wrangel Island was in decent shape when they finally disappeared about 4,000 years ago, and is therefore the unlikely cause of their extinction. Most likely, a new study led by Laura Arpe of the University of Helsinki suggests that long-term isolation on the island has made mammoths genetically weak, making them vulnerable to extreme weather. Other factors, such as poor access to fresh water and predation, have been cited as other possible causes of their death.

During the wicked reign, woolly mammoths occupied territory extending from Spain to Beringia and North America. Mammoths have flourished for hundreds of thousands of years, but something changed between 15,000 and 10,000 years ago that led to their extinction. Scientists disagree about why mammoths died out, but the end of the last ice age and habitat loss, as well as over-hunting by humans, apparently had much to do with it.

Map showing the locations of mammoths used in the new study (1 ka = 1000 years).
Image: L. Arppe et al., 2019

About 10,000 years ago, there were no mammoths – except for two isolated populations: one on St. Paul Island off the southwest coast of Alaska and one on Wrangel Island in the Arctic oceans off the northeastern coast of Siberia. It is improbable that these mammoths, depleted of raised seawater, have survived for thousands of years, but they are also extinct. The mammoths at St Paul's disappeared 5,400 years ago, and the Wrangel population wrapped things up about 4,000 years ago. And that was all – the woolly mammoths were officially made.

The fact that the mammoths were still around on Wrangel Island, which were 4,000 years ago, is extremely amazing. This is good in the Holocene period, some 6,000 to 7,000 years after the mammoths disappeared from Siberia, Beringia and North America, and several hundred years after the ancient Egyptians built the Great Pyramid of Giza. According to a new document, the extinction of Wrangel's mammoths was "rather abrupt" and "without signs of a previous population decline."

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The purpose of the new study was to find out what happened to the mammoths on Wrangel Island, and why things sour so quickly for them. To this end, researchers conducted an isotope analysis of mammoth remnants that they did to better understand the ecology of Wrangel Island during mammoth extinction. This analysis included isotopes of carbon, nitrogen and sulfur, and showed what the mammoth diet was at the time.

In total, the researchers analyzed 77 mammoth specimens from Wrangel Island, Beringia and the lower latitudes of Eurasia, as well as mammoth remains from St. Paul Island. These samples date from 40,000 to 4,000 years ago.

Wrangel's mammoth data suggest that their island habitat was beautiful at the time of their extinction. Therefore, the idea that these mammoths have died out due to the gradual degradation of the environment and the subsequent decline in the quality and quantity of their food is not in line with new evidence. Something else has to happen.

This "something else" may have something to do with their long isolation on the island.

Recent genetic studies of Wrangel mammoths show that they lacked genetic diversity and susceptible to inbreeding – factors that may have "made the population more vulnerable to extinction," the authors wrote in a new article. Compared to their ancestral Siberian ancestors of 40,000 years, Wrangel mammoths have found a significant number of deletions of genes, retrogens and other genetic abnormalities that, while not fatal, can reduce the "survival capacity of already struggling populations." according to the article.

It is important that geneticists have linked many of these gene deletions to mammoths' ability to metabolize fat, an observation found in a new study. Isotopic carbon analysis of Wrangel mammoths revealed large differences between fats and carbohydrates in the diets of Wrangel mammoths compared to their previous Siberian counterparts. This suggests that Wrangel's mammoths were less suited to enduring extreme cold conditions.

"We believe this reflects the tendency of Siberian mammoths to rely on their fat reserves to survive through the extremely harsh winters of the Ice Age, and Wrangel's mammoths living in m & # 39; m conditions are simply not needed," Arpe said in Helsinki University Press Release

Aerial weather was another factor raised in a new paper: Increasing rainfall on Wrangel Island during the Holocene caused the release of toxic chemicals such as sulfide, base metals, copper, and antimony ores on The island's central mountains, which researchers saw as traces of sulfur and strontium in the remainder of the mammoth, lack of clean fresh water did not lead to the extinction of the mammoths, but, as well as their reduced DNA, apparently did not help, according to the paper.

In spite of these difficulties, there is no evidence to suggest that the Wrangel mammoths were gradually declining and, as noted, their disappearance occurred rather suddenly. To explain their rapid extinction, researchers say that this genetically impaired population, which may be even worse with poisoned water, may have been wiped out by an extraordinary weather event.

One possibility is a phenomenon known as snow on snow, in which an impenetrable frozen layer of snow makes it impossible to graze herbivorous animals on the plants below (as a side, this actually happened in the Norwegian Svalbard archipelago last winter). The only rain event in the snow may have been the straw that broke the camel's back on Wrangel Island, reducing the mammoth population to an irreversible extent.

The notion that humans contributed to the extinction of Wrangel mangers was considered unlikely by researchers, but they did not.

The earliest archaeological evidence of humans on Wrangel Island dates to about 3650 – 3350 years ago, which is several hundred years after the mammoths left. These people survived hunting for marine mammals and geese, and there is no evidence that they hunted mammoths. At the same time, "the idea of ​​prehistoric hunters visiting the island and meeting with mammoths cannot be ruled out for the simple reasons that archeological evidence is lacking, since the likelihood of finding such evidence is low," the authors wrote, adding that future research should focus on this opportunity [19659006] Despite this, the end of the mammoths was almost certain of this point. When the Ice Age was firmly in the rearview mirror and much of the Steppe Mammoth replaced by lush forests and marauding people, these majestic beasts said goodbye to a world where they no longer had a place to live.


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