Woolly mammoths traveled far and wide

If woolly mammoths lived nowadays, they would have no problem meeting their daily step quota. Analysis of isotope distributions in a well-preserved tusk shows that the animal that grew it traveled repeatedly across vast regions of the Arctic, frequenting select areas during specific phases of its life (Science 2021, DOI: 10.1126/science.abg1134). The study provides a picture with unprecedented detail of the home range, mobility, and life history of an extinct species.

As tissues such as teeth and tusks grow, they incorporate ingested strontium, leaving a lifelong record of an animal’s diet imprinted along the length of its tooth or tusk. The ratio of 87Sr to 86Sr in soil and plants varies geographically, so the tissue can also be used to determine where an animal lived—and ate—at various stages of its life.

A team led by Matthew J. Wooller of the University of Alaska Fairbanks and Clement Bataille of the University of Ottawa obtained that information for a woolly mammoth that lived roughly 17,100 years ago. The team measured the ⁸⁷Sr/⁸⁶Sr ratio at nearly 350,000 points along the length of a 1.7-meter-long tusk—a museum specimen—and compared the results with geological isotope maps for Alaska and northwestern Canada.

The analysis, along with other measurements, enabled the team to determine where the mammoth—a male—lived and roamed as a neonate, juvenile, and adult. It indicates that the animal traveled tens of thousands of kilometers during its life and died at around age 28, most likely from starvation.

The study turned up many surprises, Wooller says. One example is the apparent increase in range and movement after 15 or 16 years. “That fits with this male reaching maturity and being encouraged to leave the herd,” he says. The starvation signature in the last year of life was another surprise. Wooller adds, “the huge magnitude of ground covered in a lifetime is truly amazing.”