A woolly mammoth that perished above the Arctic Circle spent his life as a vagabond, scientists reported this week in the journal Science.
The researchers examined chemicals deposited over time in one of the mammoth’s well-preserved tusks in order to map his movements and geographic range. They discovered that the intrepid animal roamed over most of the state of Alaska before eventually starving in the frigid north. If this wanderlust was shared by other members of his species, the findings could help shed light on why woolly mammoths died out.
“There are many questions about woolly mammoth extinction,” says Yue Wang, a paleontologist at Georgia Tech who was not involved in the research. One of the most crucial considerations is how much ground the animals covered during their lifetimes, which can help scientists understand how woolly mammoths were impacted by a changing climate and human activities.
“This research kind of solves this question,” Wang says. “This gives researchers like me some indications that the lifetime range of woolly mammoths can be very huge.”
Present-day large herbivores such as elephants and caribou regularly cover large distances, and scientists have suspected that woolly mammoths behaved similarly. But it wasn’t clear when or how far they traveled, says Clement Bataille, a geologist at the University of Ottawa in Ontario and a coauthor of the findings.
To find out, he and his colleagues analyzed a 1.7-meter-long (5.6 footlong) tusk from a male woolly mammoth that died around the age of 28 (some researchers have estimated the animals lived for about 60 years). The remains date to about 17,100 years old, during the last ice age.
When animals eat or drink, traces of elements such as strontium and oxygen are integrated into their tissues. Certain versions, or isotopes, of these elements are more common in some locations than others. The ratios of different strontium isotopes in plants and soil reflect the geology of the underlying bedrock. The oxygen isotopes found in water vary depending on climatic conditions such as distance from the coast, temperature, and elevation, Bataille says.
“[In] the mammoth, because he has a continuously growing tusk, the strontium is progressively incorporated as he’s moving across the landscape into the tusk…like kind of a GPS record of what the animal is doing,” he says.
Bataille and his colleagues had previously used hundreds of rodent teeth from museum collections to map how strontium isotopes varied in ecosystems all over Alaska. Unlike mammoths, rodents don’t migrate very far, so they can provide hyper-local data. The researchers also examined oxygen isotopes from mammoth and mastodon teeth collected across the landscape.
The team then compared the isotopic signatures found in the woolly mammoth tusk with these maps. They…