It all began 11,700 years ago. The Earth then experienced the end of one of its Ice Ages, which also marked the beginning of the end for the woolly mammoth. The climate was becoming warmer and humans were hunting more and more, causing the mammoth to gradually disappear from its vast continental habitat in Eurasia and North America. This was 10,000 years before our era.
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After this period, the mammoth left us some traces of its existence, which were discovered in 2004 on St. Paul Island in Alaskan waters. These new discoveries suggested that the animal lived in these regions 5,700 years ago. But another study revealed that mammoths actually died out on Wrangel Island, much further north.
How do we know the mammoths died out there?
A team of researchers has begun analyzing the isotopes of many woolly mammoth teeth and bones around the world to learn more about the environmental changes that these animals may have undergone.
In general, the isotopes present in the soil can be absorbed by plants, which in turn are consumed by humans and animals. Isotopes then replace some of the calcium in teeth and bones. It is by analyzing them that isotopes can be dated and mapped to geographical locations and various climate changes.
In addition, this type of observation makes it possible to gather a lot of information on the mammoth's diet and its different lifestyles up to its extinction.
The woolly mammoth mutated before it disappeared
During DNA analyses carried out in 2017, scientists found genetic mutations in mammoths on Wrangel Island, causing cognitive disorders, modifying their hair and most importantly affecting the way their bodies were managing fat.
By studying the isotopes of carbon, nitrogen, sulphur and strontium, the researchers were also able to observe a radical change in the environment and diet of these mammoths. These two discoveries lead to the same conclusion, as explained by Laura Arppe, a geochemist at the Finnish Museum of Natural History, who is leading the study:
Our findings show that Siberian mammoths relied on their fat reserves to survive during the Ice Age winters, while Wrangel mammoths living in milder climatic conditions no longer needed this ability.
An inevitable extinction
If the climate was milder, and if they were on islands, how could mammoths have disappeared, and what is more, why so suddenly? Several theories have been put forward by researchers, such as an intensely human activity that would have decimated the last populations, or a specific meteorological event like winter rains, which would have frozen the ground and made food inaccessible.
A thorough observation of the isotopes of the bedrock on the island of Wrangel also suggested a decline in the quality of drinking water on the island, which possibly caused diseases or even multiple deaths due to animal dehydration, as explained by Hervé Bocherens, a geoscientist at the University of Tübingen:
It is easy to imagine that the population, perhaps already weakened by problems of genetic deterioration and drinking water quality, would have succumbed to an extreme weather event.
