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An international team of researchers led by Dr. Liora Kolska Horwitz of the Hebrew University of Jerusalem’s National Natural History Collections, working at the site of the oldest dated intentional use of fire by ancient human ancestors, South Africa’s Wonderwerk Cave, has found new evidence pushing that date even earlier into prehistory.
The research team behind the potentially history-altering findings said the discovery, which suggests that ancient hominins intentionally controlled fire, resulting in charred animal bones sometime between 1.07 and 1.79 million years ago, provides researchers with previously unavailable insights into how our ancestors first began to harness one of the most important tools in the evolution of human society and culture.
The study also introduced the archaeological community to a promising new method for analyzing burned bone samples by monitoring its light-emitting properties.
According to a statement announcing the study, Dr. Horwitz, who is co-director of the Wonderwerk Cave project with Prof. Michael Chazan at the University of Toronto, and colleagues note the historical significance of fire, ranging from warmth and predator protection to extended daylight and the cooking of meat. However, historians have struggled to identify a single moment or historical period where humanity’s ancient ancestors first started to use fire intentionally.
“Evidence of fire from such ancient sites is often subtle and difficult to detect,” Dr. Horwitz explained.
Before the new analysis, the oldest agreed-upon evidence for intentional fire use also came from Wonderwerk Cave. Situated within the Kalahari Desert of South Africa, the cave provided evidence placing fire use to approximately 1 million years ago.
While that study used the most advanced techniques available, the team behind the new study decided to employ a non-invasive process that involves illuminating ancient bone fragments with specific wavelengths of light to determine whether they had been exposed to intense heat. In cases where bones have been heated to fire-like temperatures, the right wavelength of light will cause them to glow.
Because evidence from ancient sites is scarce, the team’s non-invasive technique allowed them to study tiny fossilized rodent bones left in the cave by owls without damaging them. The team noted that using remains that accumulated naturally on the ancient cave floor provides an “independent, non-anthropogenic record” of ancient events within the local area.
After exposing the ancient bone to specific wavelengths of light, the team found what they described as “clear signs of burning.” Dr. Horowitz confirmed the findings, noting that the team’s analysis reveals “fire was repeatedly present deep inside Wonderwerk Cave.”
Because the deposits were found over 30 meters deep in the cave, the team ruled out wildfires as a possible source of combustion. The layer also lacked bat guano remains, which the team noted “rules out spontaneous combustion.”
A chemical analysis of the charred bones dated them to between 1.07 and 1.79 million years ago, redating the 2012 findings. Critically, the evidence for ancient fire use was in an archaeological layer “associated with artifacts” from the initial Acheulean period, which is consistent with the dating. If correct, this would make the likeliest early human ancestor that used fire Homo erectus.
Although the findings appear to extend the chronology of one of the earliest known records of fire use associated with hominins by as much as 790,000 years, the research team said the findings do not suggest that these early proto-humans could create fire “at will.” Instead, the likeliest scenario involves early human ancestors collecting fire from natural sources, such as lightning-induced wildfires on the African savanna, and bringing it into the cave.
“The early humans introduced this fire into the cave on multiple occasions and maintained it there before it eventually died out,” the team’s statement explained.
The team did not immediately pinpoint what methods these early hominins used to maintain a burning fire. However, they suggested that burning owl pellets as additional fuel may inadvertently have scorched the rodent bones.
When discussing the implications of the new, earlier date for the first intentional use of fire, Dr. Horwitz said the discovery shows that early human ancestors “were not simply passive observers of natural fires,” but instead were “actively engaging with fire and incorporating it into their lives.”
Beyond offering an earlier date range for early fire use, the work provides clues into how our ancestors used fire before they could make it on their own. The study also debuted a new, non-invasive, portable tool for investigating early fire use, which the study authors note “can be applied to large collections of fossils without damaging them.”
“Our study provides new tools for identifying traces of ancient burning,” Dr. Horwitz explained, with the team adding that application of this new technique to sites around the world “may help clarify the origins and development of one of the most consequential technologies in human history.”
The study “New evidence for Early Pleistocene use of fire at Wonderwerk Cave (South Africa)” was published in PLOS One.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.
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