Washington (AFP)

A distance equivalent to twice the circle of the Earth in 28 years of life: researchers have retraced the path traveled by a woolly mammoth that lived about 17,000 years ago in Alaska, proving for the first time that this iconic animal was indeed a great walker.

Their discovery, published Thursday in the prestigious journal Science, could shed light on the hypotheses on the extinction of this gigantic mammal, whose teeth were larger than a human fist.

"In all popular culture, for example if you watch (the cartoon) + the Ice Age +, there are always mammoths who migrate, who move, who move around a lot", noted Clément Bataille, assistant professor at the University of Ottawa and one of the lead authors of the study. But there is "no real reason, because it is such a huge animal that moving around uses a lot of energy," he told AFP.

And yet, the researchers were amazed by their results: the mammoth studied traveled an "enormous" distance, about 70,000 kilometers, and did not settle into a plain as they expected.

"We see that it travels throughout Alaska, therefore an immense territory", underlines Clément Bataille.

"It was really a surprise."

- Readings on a tusk -

For their work, the researchers selected a male who lived at the end of the last ice age.

A particularly interesting specimen, because it is quite recent and therefore close to the time of the extinction of its species, around 13,000 years ago.

One of the two tusks was cut in half to take readings of so-called "strontium isotope ratios".

Strontium is a chemical element very similar to limestone.

Isotopes are different forms of this element.

Present in the soil, strontium is transmitted to vegetation, and when the latter is ingested by a living being, it is placed in bones, teeth ... or tusks.

These last grow continuously: the tip reflects the first years of life, and the base the last.

A mammoth tusk cut in half and studied to trace the course of this animal, on an undated image transmitted by the University of Alaska Fairbanks JR Ancheta University of Alaska Fairbanks / AFP

As the isotope ratios are different depending on the geology, Clément Bataille developed an isotopic map of the region.

By comparing it with the data from the tusks, it is thus possible to say precisely when the mammoth was where.

- Long trips -

At the time, glaciers covered all of the mountains of the Brooks range in the north and the Alaska range in the south.

In the center is the plain of the Yukon River.

In general, the animal returned regularly to certain areas, where it could stay for several years.

But his movements have changed greatly depending on his age, before he eventually died of hunger.

During the first two years of her life, researchers were able to observe signs of breastfeeding.

Then between 2 and 16 years, movements are recorded, but mainly in central Alaska.

"What was really surprising was that after the teenage years, the isotopic variations start to be much more important", explains Clément Bataille.

The mammoth has, "three or four times in its life, made an immense journey of 500, 600, even 700 kilometers, in a few months."

To explain such movements, scientists have two hypotheses.

As with elephants, perhaps this male mammoth moved solitary, from herd to herd, to reproduce.

Or maybe he was facing a drought or a particularly harsh winter, forcing him to seek out an area where food was more plentiful.

- Lessons for today -

Whether for questions of genetic diversity, or of resources, it is "clear that this species needed an extremely large area" to live, points out Clément Bataille.

However, at the time of the transition between the ice age and the interglacial period, that is to say at the time of its extinction, "the area was reduced, because more forests grew" and "the humans exerted a rather strong pressure on the south of the sea. 'Alaska, where mammoths probably moved a lot less,' he explains.

According to the researcher, understanding the factors that led to the disappearance of mammoths can help protect other currently threatened megafauna species, such as caribou or elephants.

Today, on the one hand, climate change is warming the planet.

On the other hand, "we are going to restrict these species of megafauna to parks" or protected areas, he says.

"Do we want our children 1,000 years from now to view elephants the same way we view mammoths today?"

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