Scientists have uncovered new evidence that early human ancestors were using fire between 1.07 and 1.79 million years ago in South Africa’s Wonderwork Cave. The discovery pushes back one of the oldest known records of fire use involving hominins and provides new clues about how our ancestors first learned to use fire.
Using a newly developed technique that can detect signs of burning in fossilized bones, researchers identified evidence of repeated fires inside the cave. Because these marks were found far away from the reach of natural wildfire, the findings suggest that early humans intentionally brought naturally occurring fire into the cave and kept it burning.
The research was conducted through an ongoing collaboration with an international team of scientists from Spain, Argentina, Canada, the US, South Africa, Portugal and Israel, led by Dr. Leora Kolska Horwitz of the Hebrew University of Jerusalem’s National Natural History Collections (co-director of the Wonderwork Cave Project with Professor Michael Chazan of the University of Toronto). This project combines archaeology, paleontology, geology, and other scientific approaches to examine one of the most important developments in human evolution: the use of fire.
Earlier evidence of the use of fire
The new study builds on earlier work in Wonderwork Cave, located in the Kalahari Desert of South Africa. In 2012, members of the research team reported evidence of fire dating back approximately ~1 million years (published by team members in PNAS in 2012), which was believed to be the oldest known evidence of deliberate fire use anywhere in the world.
Continued excavation and analysis has now extended that timeline. Researchers identified traces of fire use in archaeological deposits dating back 1.07 to 1.79 million years, making Wonderwork Cave one of the oldest known sites associated with hominin fire use. The findings, published in PLOS One, provide new insight into how ancient human ancestors may have interacted with fire long before they learned how to generate it themselves.
Fire provided many benefits, including warmth, protection from predators, illumination after dark, and ultimately the ability to cook food. Nevertheless, determining when humans first began using fire remains one of archaeology’s most difficult questions.
“Evidence of fire from such ancient sites is often subtle and difficult to detect,” said Dr. Kolska Horwitz. “Our study provides new tools for identifying ancient burn marks and shows that fire was repeatedly present inside Wonderwork Cave.”
New technique detects burnt fossil bones
The study also introduces a new approach based on the light-emitting properties of burnt bone.
When exposed to specific wavelengths of light, bones that experience intense heating produce a characteristic glow. The researchers combined this non-destructive luminescence method with established chemical analyses, allowing them to identify burnt animal bones with a high level of confidence.
This technique is portable, non-invasive and can be used on large fossil collections without causing any damage.
To test the method, the team examined hundreds of small fossilized bones left by owls that once lived inside the cave. Because these remains are deposited naturally over time, they provide an independent, non-anthropogenic record of past events preserved on the cave floor.
Fire deep inside Wonderwork Cave
The researchers discovered clear evidence of burning within an archaeological layer associated with early Acheulean artifacts, possibly associated with Homo erectus. The charred remains were found about 30 meters inside the cave, far from the area that could have been affected by natural wildfire. They were also located in a layer that lacked guano deposits, ruling out spontaneous combustion as an explanation.
The evidence does not suggest that these early humans were capable of creating fire whenever they wanted. Instead, the findings indicate that they probably collected fire from natural sources, such as lightning strikes or wildfires on the African Savanna.
According to researchers, these ancient humans would have brought fire to the cave several times and maintained it for some time before it was eventually extinguished. The team also suggested that the owl pellets could serve as fuel, which might explain why the small rodent bones contained within them show signs of burning.
Nevertheless, the ability to carry fire and keep it burning inside a cave represents a major behavioral milestone.
“These discoveries show that early humans were not simply passive observers of natural fires,” explained Dr. Kolska Horwitz. “They were actively connecting with fire and incorporating it into their lives.”
A new window into the origins of fire
In addition to extending the timeline of fire use, the study provides archaeologists with a valuable new tool to determine when and how humans first began using fire.
As scientists apply this technique to archaeological sites around the world, it could help answer long-standing questions about the origins and evolution of one of the most transformative technologies in human history.