Mammoths are one of the most famous residents of the last ice age, but their journey through the tundra has long been a mystery. Now, experts use the chemical composition of 17,100-year-old mammoth ivory from Alaska to map where this animal wanders during its lifetime. They found that its mileage was almost enough to circle the world twice.
During the last ice age, mammoths roamed North America, Europe, and northern Asia. Most were extinct about 10,000 years ago, and a few populations survived on a small island in the Arctic Ocean until about 2000 BC. Today, millions of long, heavy ivory from the now extinct giant are buried in the Arctic and Siberian earth. They are still intact, so much so that they are sought after as a source of commercial ivory. But their value is not only ornamental. “Ivory is like a timeline,” said Matthew Wooler, a paleoecologist at the University of Alaska Fairbanks and the first author of the new paper.
A silver alkaline earth metal called strontium has different versions or isotopes, each with a different atomic mass. The ratio of these isotopes varies in soils around the world. When mammals eat plants that grow in these soils, their bones and teeth contain a small amount of strontium-for mammoths, their tusks are modified incisors.
Catherine Smith, a paleontologist at Georgia Southern University who was not involved in the new study, said that ivory “is an excellent record of the history of the earth because they grow in layers.” By dividing the ivory into two and examining the many chemical layers in it, Wooller and his collaborators began an unprecedented analysis: They mapped the journey of the ivory owner 17,000 years after his death.
Wooller and his team cleverly split the elephant tooth in two from the middle-this is a risky task that requires careful planning and leads to what Wooller calls “a year’s nightmare”, which is to break it and make it change. It’s useless. The researchers then measured the ratio of strontium isotopes on the five-and-a-half-foot-long ivory and compared them to create a route for the mammoth to roam.
Tusk comes from a male mammoth who lived about 28 years old in what is now Alaska during the last ice age. In its lifetime, It walked nearly 50,000 miles, Team report science, Challenged some people’s impression that mammoths are more sedentary beasts. “All of us entered this project with preconceived ideas about the behavior of mammoths,” Wooler said. But the researchers finally got “one surprise after another.”
When the mammoth was young, it was likely to be part of a herd in the interior of Alaska, similar to the behavior of modern mammoths. At around 16 years of age, at the beginning of sexual maturity, it will attack on its own and travel long distances on both sides of the Arctic Circle. During the last year and a half of its life, it stayed mainly in a small area in what is now northern Alaska. The isotopic signature of Telltale suggests that it may starve to death near the foothills of the Brooks Mountains.
“One of the really exciting things is to see how this mammoth’s range of activity changes with the different stages of its life,” Smith said. The fact that its range expands at the age of 16 “Really cool, this is what we see on elephants.” The size of the woolly mammoth is about the same as the largest land mammal in Africa today. These two are related. Species have other similar characteristics. Like their modern counterparts, mammoths live in matrilineal groups, and Smith wants to know the difference in lifetime mobility between males (such as the one in Wooler’s study) and females. Wooller and his team plan to apply the same technique to more specimens in the next few years. “We have hundreds of mammoth tusks,” he said. “We are happy to make more ivory.”
This article originally appeared in Science spectrum And reprinted with permission.