Fire Use at Wonderwerk Cave Pushed Back to 1.79 Million Years
Deep inside a cave in South Africa’s Kalahari Desert, tiny burned bones from owl pellets are rewriting one of the oldest chapters in the human story. The evidence now suggests our ancestors were carrying fire indoors, so to speak, hundreds of thousands of years earlier than previously confirmed.
Extending an Already Remarkable Record
A new study has uncovered evidence that early human ancestors were using fire in South Africa’s Wonderwerk Cave between 1.07 and 1.79 million years ago, extending the chronology of one of the earliest known records of fire use associated with hominins. The research was led by Dr. Liora Kolska Horwitz of the Hebrew University of Jerusalem’s National Natural History Collections, co-director of the Wonderwerk Cave project alongside Professor Michael Chazan of the University of Toronto, working with an international team spanning Spain, Argentina, Canada, the United States, South Africa, Portugal, and Israel. The findings were published in the journal PLOS One.
The current paper builds directly on earlier work at the same site. In 2012, members of the same research team had already dated evidence of fire at Wonderwerk Cave to approximately 1 million years ago, a finding published in PNAS that stood at the time as the oldest evidence for intentional fire use anywhere in the world. The new study pushes that timeline back by extending investigation into a deeper, older layer of the cave.
A New Way to Spot an Old Fire
Determining whether an ancient bone was actually burned, rather than simply discolored by the slow chemistry of fossilization, has always been a genuine technical challenge. “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.”
To meet that challenge, the team applied a new method based on the light-emitting properties of burned bone. When illuminated with specific wavelengths of light, bone that has been exposed to intense heat gives off a distinctive glow. By combining this non-destructive luminescence technique with established chemical analyses, researchers were able to identify burned animal bones with a much higher degree of confidence than earlier methods allowed, all without damaging the fossils themselves.
Reading History in Owl Pellets
The team applied this new method to hundreds of tiny fossil bones left behind by barn owls that had roosted inside the cave over enormous stretches of time. Because these remains accumulated naturally on the cave floor through ordinary owl activity, unrelated to human behavior, they offer an independent, non-anthropogenic record of what was happening inside the cave at different points in its history.
Analysis revealed clear signs of burning in an archaeological layer associated with Initial Acheulean stone tools, artifacts most likely linked to Homo erectus. Crucially, these burned remains were found roughly 30 meters inside the cave, far beyond where any natural wildfire could possibly have reached, and in a layer that lacked guano deposits, which rules out spontaneous combustion as an alternative explanation.
Borrowed Fire, Not Manufactured Fire
The findings don’t suggest these early humans could create fire whenever they wanted. Instead, the evidence points toward the use of naturally occurring fire, likely sparked by lightning strikes or wildfires out on the African savanna. Early humans appear to have carried that borrowed fire into the cave on multiple separate occasions and kept it burning there for a time before it eventually died out.
The team suggests the owl pellets themselves may have served a practical purpose in this process, potentially used as fuel, which would explain why the small rodent bones embedded inside them show burn marks. Even without the ability to strike fire from scratch, repeatedly transporting flame into a dark cave interior and tending it there represents a genuinely significant behavioral leap. “These discoveries show that early humans were not simply passive observers of natural fires,” Kolska Horwitz explained. “They were actively engaging with fire and incorporating it into their lives.”
Why This Matters Beyond a Single Cave
Fire’s importance to human evolution is difficult to overstate. It provided warmth, protection from predators, and light after dark, and it eventually made cooking possible, a shift some researchers have linked to major changes in human diet and physiology over time. Precisely when that relationship with fire began, however, has remained one of archaeology’s most difficult and long-debated questions, largely because the physical evidence tends to be faint and easily confused with natural discoloration.
This study doesn’t claim to settle the broader question of when cooking itself began, since finding evidence of controlled fire inside a cave is a distinct question from proving that fire was being used specifically to prepare food. What it does offer is a considerably more secure foothold at the far end of the fire-use timeline, evidence that early humans were engaging with fire, deliberately and repeatedly, nearly 800,000 years earlier than the previous benchmark set by the same research team’s own 2012 findings.
A Tool for the Rest of the World
Beyond extending the specific record at Wonderwerk Cave, the study hands archaeologists a genuinely useful new instrument. The luminescence-based method is non-invasive, portable, and can be applied to large fossil collections without damaging a single specimen, making it well suited for reexamining other ancient sites where fire evidence has proven difficult to confirm.
As researchers begin applying the technique at additional archaeological sites around the world, it may help resolve one of the more persistent puzzles in human evolution: exactly when, and how, our ancestors first began to make one of history’s most consequential technologies their own.
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