An international team led in part by researchers from the Hebrew University of Jerusalem has uncovered evidence suggesting that early human ancestors were using fire in South Africa’s Wonderwerk Cave between 1.07 million and 1.79 million years ago, pushing back one of the earliest known records of fire use.

The findings, published in the peer-reviewed scientific journal, PLOS One, build on earlier research at the cave that established evidence of intentional fire use dating to about 1 million years ago. The new study extends that chronology and offers fresh insight into how early human beings may have harnessed naturally occurring fire long before learning to create it themselves.

The research is part of an ongoing collaboration between Dr. Liora Kolska Horwitz of the Hebrew University’s National Natural History Collections, who co-directs the Wonderwerk Cave project with Prof. Michael Chazan of the University of Toronto, and an international team spanning institutions in Israel, South Africa, Canada, Spain, Portugal, Argentina, the United States and Britain.

The breakthrough was made possible by a new, non-destructive technique that detects traces of burning in fossilized bones using their light-emitting properties.

“Evidence of fire from such ancient sites is often subtle and difficult to detect,” Kolska Horwitz said. “Our study provides new tools for identifying traces of ancient burning and reveals that fire was repeatedly present deep inside Wonderwerk Cave.”

Wonderwerk Cave, in South Africa’s Kalahari Desert, is one of the world’s most important prehistoric archaeological sites, preserving evidence of human occupation dating back nearly 2 million years.

When exposed to specific wavelengths of light, bones that have been subjected to intense heat emit a distinctive glow. By combining the luminescence technique with established chemical analyses, researchers were able to identify burned animal bones with a high degree of confidence without damaging the fossils.

The scientists examined hundreds of tiny fossil bones left behind by owls that once roosted in the cave. Because the remains accumulated naturally on the cave floor, they provide what researchers describe as an independent record of ancient events.

Clear signs of burning

The team found clear signs of burning in archaeological layers associated with the early Acheulean period, likely linked to Homo erectus. Significantly, the burned remains were discovered about 30 meters (nearly 100 feet) inside the cave—well beyond the reach of natural wildfires—and in layers lacking guano deposits that could have ignited spontaneously.

The findings do not suggest that these early human beings knew how to make fire at will. Rather, researchers believe they brought naturally occurring fires—possibly sparked by lightning or savanna wildfires—into the cave and maintained them before they eventually died out. The team also suggested that owl pellets may have been used as fuel, resulting in the burning of the tiny rodent bones they contained.

“These discoveries show that early humans were not simply passive observers of natural fires,” Kolska Horwitz said. “They were actively engaging with fire and incorporating it into their lives.”

Fire would have provided warmth, protection from predators and light after sunset, and would eventually transform human society through cooking and other technological advances.

Beyond extending the known timeline for fire use, the researchers say the new method could become an important tool for archaeologists investigating one of the most consequential developments in human evolution.

As the technique is applied at archaeological sites around the world, it may help answer one of prehistory’s most enduring questions: when—and how—our ancestors first learned to harness fire.