Woolly Questions

Art Courtesy of Patricia Joseph.

For all our Ice Age movies, artistic renderings, and sci-fi murmurings of de-extinction, mammoths have never quite lost their mythic proportions. The thirteen-foot darlings of every natural history museum continue to loom with about as much mystery as majesty. We know that they roamed the tundra steppes for roughly 290,000 years, during which they grazed on arctic plants, briefly brushed shoulders with prehistoric humans, and had their likenesses transferred onto cave paintings. Then, around the time humans were building pyramids, they disappeared. The causes for their extinction—human hunting, climate change, or some mix of both—have been hotly debated as they remain tantalizingly unclear.

Enter Elma, an ancient woolly mammoth, and one of only two specimens with complete tusks in all of Alaska. In a study published last month in Science, Elma is the star as a team of anthropologists and biologists provides an intricate reconstruction of her entire lifetime with the help of isotopic dating technologies. As just the second mammoth reconstruction of its kind, it offers an intimate glimpse into the creature’s habits—and an enticing glance at what mammoth interactions with early humans may have looked like.

“We can’t […] say for sure that humans killed this mammoth, but we’ve got means and motive at this point,” said Audrey Rowe, a PhD candidate at the University of Alaska and the lead researcher on the study. Elma was uncovered at Swan Point, the oldest archaeological site in Alaska, by researchers during the early 2000s. 

The study’s genetic and isotopic analysis chronicles an impressive yet punishing journey through the Alaskan hinterlands that ends in a cryptic fashion. According to the study, Elma trekked roughly one thousand kilometers from southeast Beringia, in present-day Canada, deep into interior Alaska in the span of two and a half years. Then, still at the peak of her life and roughly twenty years old, she died—right next to an area of known human settlement.

This cold case has the set-up of a prehistoric Agatha Christie plot, but there’s no smoking gun. Elma’s remains were uncovered alongside another closely related juvenile and a newborn and were dated from around the same time humans had started populating the region. She died in healthy condition, and her body lacked physical evidence of having been hunted, unlike mammoth samples in Siberia or Poland, which feature spear points lodged in spinal vertebrae or microblades buried in ribs.

All signs nonetheless point to death by humans. “These early people in Alaska also certainly seem to have the technology […] to bring down a mammoth,” said Matthew Wooller, a University of Alaska professor of chemical oceanography and author of the study. Elma was found in the same time layer as the remains of the two younger mammoths, and her path overlaps neatly with human settlement at a time when they were capable of developing lethal stone projectiles—there are simply too many coincidences.

Researchers were just as lucky to come across a tusk as uncompromised as hers. The equivalent of rings on a tree trunk, mammoth tusks offer telling records of life. Rowe explained that their tusks—similar to those of elephants—stack new layers atop each other as they grow, almost like ice cream cones. Elma’s tusk unraveled her story from the tip to her trunk.

Using recently developed isotope analysis techniques, the researchers were able to chart Elma’s footsteps across prehistoric Alaska. They sliced open her tusk, drilled into the ivory at millimeter-length increments, and measured the isotopic ratios of strontium, sulfur, and oxygen—all of whose stable half-lives can be deeply informative. Levels of strontium-87, an isotope formed in rocks by decaying rubidium, vary across the world; what follows is a telltale geographic signature, since strontium can vary across mountain ranges or even just a few valleys. The broad outlines of Elma’s journey took shape when researchers paired their isotope measurements with maps that captured the geographic distribution of strontium-87 ratios. Once coupled with oxygen-18 and sulfur-34—which can track water sources and mean annual temperature, respectively—the 14,000-year-old picture became even clearer. What the data sketched was a trek inland, across highlands and the more arid swaths of the tundra.

Peripatetic, or nomadic, mammoths are no strangers to long-distance, cross-continental hauls. Wooller explained that the previous study of this kind—featuring an 18,000-year-old male—had unearthed even longer treks that had taken the mammoth to similar regions in interior Alaska. Sexual differences were probably at play: like elephants, male mammoths may have left their herds at a younger age and traveled more during their lifetimes.

Roaming some three thousand years after her male counterpart, this study’s mammoth offers a more dramatic portrait of her kind’s sunset, and of an arctic habitat hardly recognizable from the one we might imagine today. “A lot of Alaska was not covered by ice at all,” Wooller said. The mammoth population would have peaked some six thousand years before Elma. The Last Glacial Maximum—the last moment when glaciers covered nearly eight percent of the world’s total surface—had ended, ushering in scrubby forests that crept onto riverbanks and cropped up along the steppes.

For a species so used to their barrenly flat haunts, the dramatic ecological changes would have fractured habitats and made them increasingly vulnerable to predation. The mammoths gravitated towards the same regions as human settlements and increasingly crossed paths with our earliest ancestors. Some combination of human-driven extinction and the forces of climate change likely led to the mammoth’s demise. “I think, at least in interior Alaska, the answer is more nuanced than that black or white,” Rowe said.

Like the mammoth’s shaggy, fifty-centimeter coat, the details remain understandably hairy; piecing together the entire arc of a species calls for a sample size greater than just two. Wooller and Rowe both pointed out the need to analyze more sequences of this kind. In the interim, research could also take new directions—Wooller noted that recent excavations in Canada and Siberia have detected mammoth DNA in permafrost layers less than ten thousand years old, indicating the possibility of late-surviving groups.

“Now that we’ve got something more about the mobility of the animals in this region, it would be great to get at the people as well,” said Ellery Frahm, a Yale anthropology professor not involved in the study. Frahm, whose research focuses on early human group interactions in Eurasia, explained that tracking mammoth movements is crucial to discovering the ways our ancestors engaged with their food sources.

For the researchers, simply coming face to face with our mammoth ancestors is as fulfilling as playing detective. “It’s more exciting to just be learning about mammoth behavior because we have so little knowledge about that right now,” Rowe said. “Studies like this one are starting to actually pin down some actual truths instead of forcing us to make these assumptions.” Amid the decades-long buzz of mammoth DNA extraction and de-extinction projects, tracing their stories may well be the truest gesture of bringing them back to life.

Elma would have been about 13,600 years old by the time “mammoth” entered the dictionary. It came with Russian roots, surfacing in the English vocabulary during the eighteenth century and coming to signify largeness. Big. Colossal. Huge. Gigantic, still fitting today for animals about which there can never be too much space for wonder or questions.