A new technique to identify ancient fires has pushed the known timeline of early human fire use and interaction back to about 1.8 million years ago, according to a new study.

The study builds on the previous discovery, published in a 2012 study in the scientific journal PNAS, which revealed traces of early humans using fire at Wonderwerk Cave in the Kalahari Desert of South Africa as early as one million years ago.

Here, however, researchers using a new method of identifying traces of ancient fires based on the light-emitting properties of burned bone succeeded in pushing back the timeline to 1.07 and 1.79 million years ago.

Researchers explained that when bones exposed to high heat are illuminated with specific wavelengths of light, they light up with a distinctive glow.

Combining this technique with certain chemical analyses, researchers were able to identify burned animal bones with a “high degree of confidence.”

"Evidence of fire from such ancient sites is often subtle and difficult to detect," explained Prof. Kolska Horwitz of the Hebrew University of Jerusalem. "Our study provides new tools for identifying traces of ancient burning and reveals that fire was repeatedly present deep inside Wonderwerk Cave."

The new method is groundbreaking for several reasons: it is non-invasive, portable, and can be used on large collections of fossils without causing damage.

Using this method, researchers analyzed traces of burning on hundreds of tiny, fossilized bones left behind by owls that had once roosted in the cave. 

“Because these remains accumulated naturally on the cave floor,” the study noted, “they provide an independent, non-anthropogenic record of ancient events.”

From the bones, the researchers have discovered clear evidence of fire in an archaeological layer where artifacts believed to be associated with Homo erectus have previously been found.

The location of the remains is also significant. Found approximately 30 meters inside the cave, hidden away from the reach of wildfires and lacking guano remains, indicating that naturally occurring fires - likely those sparked by lightning or wildfires - may have been brought inside to be used until they died out.

Further, the study suggested that the early humans may have used owl pellets as fuel, resulting in the hundreds of tiny burnt rodent bones that researchers studied.

“Nevertheless, bringing fire into a cave and maintaining it represents a significant behavioral achievement,” the study affirmed.

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

The study, titled “New evidence for Early Pleistocene use of fire at Wonderwerk Cave (South Africa),” was published in the journal PLOS One in June 2026 by an international team made up of Hebrew University of Jerusalem researchers, as well as those from Spain, Argentina, Canada, USA, South Africa, Portugal, and Israel.