The first person to reach the North Pole was the American explorer Robert Peary, in 1909. Or maybe it was Frederick Cook, in 1908. Historians still aren’t sure which man really made it there first.

At any rate, it’s a fitting story of discovery for the Arctic, a corner of the world where ambiguity reigns. There isn’t even an official consensus on the exact parameters of the label: Technically, the Arctic refers to anything above the Arctic circle, which has a latitude of 66 degrees, 32 minutes North, but the U.S. definition includes all of the Bering Sea (which stretches as far south as 53 degrees), and some scientists use the Arctic tree line or average temperatures to draw their boundaries. And many of the region’s research stations are built on sheets of sea ice, drifting masses that have no true fixed location.

Also adrift is our current understanding of when humans arrived in the Arctic. In a new paper published today in Science, a team of Russian researchers made the case that humans occupied the region as early as 45,000 years ago, several millennia earlier than archaeologists had previously believed.

But the discovery on which they base their argument isn’t a frozen mummy, or any sort of man-made object. Instead, it’s the body of a mammoth, discovered in 2012 on the shores of Siberia’s Yensei Bay. The researchers were able to date the bone to around 45,000 years ago, an age supported by analysis of branches, peat, and other natural materials found around and on top of the body.

This mammoth was conspicuously healthy before it died. An examination of its teeth put it at around 15 years old at the time of its death, while the large amount of fat in its hump (much of its soft tissue remained intact) indicated that it was generally healthy, ruling out disease as the likely cause of its demise.

In fact, the researchers said, the carcass is marked in such a way that could only have been caused by human-made weapons. A small, symmetrical hole on the skull indicated that the mammoth had been pierced by a spear, as did dents on the leg and shoulder bones; further analysis revealed that the injuries had happened before the animal’s death, meaning these changes to the bone weren’t just the result of wear and tear over the millennia. Pieces of the trunk had also been stripped away, which the authors speculate may have been a way for the animal’s hunters to make the tools they needed to butcher it.

To back up their findings, the study authors also cited the recent discovery of a wolf carcass from a separate location in the Siberian Arctic. A bone analysis dated the wolf to around the same time period as the mammoth, while X-rays found a mark on one of the leg bones to be “a result of a penetrating injury inflicted by a sharp weapon.” The bone also showed signs of healing, indicating that the wolf survived the injury and eliminating the possibility that it occurred after the animal’s death.

“These two incidents suggest that even during the early phases of [Marine Isotope Age 3, the period of time between 3,000 and 57,000 years ago], humans inhabited the Arctic quite widely, although the population was probably small and remained sparse for a long time,” the researchers wrote.

It’s the second time in just over a decade that a Siberian discovery has given archaeologists reason to rethink their timeline for the region. In 2004, a team of researchers led by Vladmir Pitulko, an archaeologist at the Russian Academy of Sciences and one of the new Science paper’s lead authors, discovered 31,000-year-old hunting tools along the Yana river in central Siberia, pushing back evidence for a human presence by around 15,000 years.

Unlike the 2004 find, though, this more recent paper is notable for its suggestion that a gap in human history could be filled in without any actual humans (or human-made objects) as physical evidence. And in an area where harsh conditions, inaccessibility, and permanently frozen ground make archaeological expeditions difficult, it may help researchers collect more information to add to their relatively sparse knowledge of the prehistoric Arctic.

“Huge spaces remain almost (or totally) unpopulated even in the 21st century,” Pitulsko wrote in an email. “Because of that, they remain weakly studied, almost unexplored in terms of the history of human population.”