Mammoth Tusk Analysis Reveals Epic Lifetime Journey around Alaska
Researchers find the mammoth walked far enough to circle the globe twice
By Esther Megbel, Tess Joosse on September 9, 2021
Mammoths are among the best-known inhabitants of the last ice age, but their travels across the tundra have long remained a mystery. Now experts have used the chemical composition of a 17,100-year-old mammoth tusk from Alaska to map out where the animal wandered during its lifetime. They found it put in almost enough miles to loop around the world twice.
Woolly mammoths roamed North America, Europe and northern Asia during the last ice age. Most died out about 10,000 years ago, with a few populations surviving until around 2000 B.C. on a small island in the Arctic Ocean. Millions of long, hefty tusks from the now extinct giants are buried in the Arctic and Siberian earth today, still so intact that they are sought after as sources of commercial ivory. But their value is not just ornamental. “Tusks are like timelines,” says Matthew Wooller, a paleoecologist at the University of Alaska Fairbanks and first author of the new paper.
A silvery, alkaline earth metal called strontium comes in different versions, or isotopes, each with a different atomic mass. The proportions of these isotopes vary in soils around the world. When mammals eat plants growing in these soils, small amounts of strontium are incorporated into their bones and teeth—and, in the case of mammoths, their tusks, which are modified incisors.
Tusks “are excellent records of Earth’s history because they grow in layers,” says Kathlyn Smith, a paleontologist at Georgia Southern University, who was not involved with the new study. By bisecting a tusk and examining the many chemical layers within, Wooller and his collaborators began a first-of-its-kind analysis: they mapped the travels of the tusk’s owner 17,000 years after it died.
Wooller and his team delicately sliced the tusk in two down the middle—a risky task that required careful planning and caused Wooller what he calls “a year of nightmares” about shattering it and rendering it useless. The researchers then measured the ratios of strontium isotopes along the five-and-a-half-foot-long tusk and compared them to create an itinerary of where the mammoth wandered.
The tusk came from a male mammoth who lived to be about 28 years old during the last ice age in what is now Alaska. Throughout its lifetime, it walked nearly 50,000 miles, the team reports in Science, challenging an impression among some that mammoths were more sedentary beasts. “All of us went into the project with a preconceived idea of what mammoth behavior is,” Wooller says. But the researchers ended up with “surprise after surprise after surprise.”
https://www.scientificamerican.com/arti ... und-alaska