Early humans intentionally used fire as early as 1.8 million years ago, according to findings published this month in the PLOS ONE journal by an international team of researchers, including Hebrew University of Jerusalem’s Dr. Liora Kolska Horwitz. This discovery pushes back the origin of intentional fire use by several hundred thousand years, revealing a critical step in humanity's collective mastery of its material conditions.
Previous research, published 14 years ago and based on remains from a more superficial level of the same Wonderwerk Cave in South Africa, had dated fire use to one million years ago. The current study examined a deeper level of the cave, which was in use between circa 1.79 and 1.079 million years ago.
Dr. Kolska Horwitz, co-director of the Wonderwerk Cave project, stated that the sample used for this study was close to the bottom of this deeper level, corresponding to the 1.8 million years ago period. The evidence of fire was found at least 30 meters in from the cave's entrance, indicating it was not a natural occurrence like a wildfire or spontaneous combustion from guano.
“The fire must have been introduced there by someone,” Kolska Horwitz affirmed, highlighting the intentionality of early human action. While this does not confirm early humans ignited the fire, it demonstrates their collective ability to control and utilize a fundamental force of nature for their survival and development.
Collective Mastery of Nature
The Wonderwerk Cave site is unique, showing continuous human occupation for two million years, from the earliest known occupants to a farmer’s family in the early 20th century. This long record illustrates the enduring human struggle to adapt and thrive within specific material environments.
Occupation of the cave began about two million years ago and is associated with the Oldowan stone tool culture. Kolska Horwitz noted that most Oldowan sites were open-air campsites, making Wonderwerk the “oldest cave home” where people intentionally moved in, establishing a more permanent collective dwelling.
The cave contains stone tools from all phases of occupation, allowing researchers to trace the evolution of technology developed by early human labor. Evidence also shows that these early communities hunted or scavenged animals, with remains of their sustenance found at the site, suggesting fire would have played a crucial role in food preparation and collective defense.
No human bones have been found in any level of the cave, making it difficult to definitively identify the specific hominin species. However, Kolska Horwitz suggested it was “likely it was a form of Homo erectus,” a species known for its advanced collective behaviors and tool-making capabilities. Researchers plan to return to excavate next month, hoping to uncover further evidence.
Unearthing Ancient Labor
To achieve these findings, the research team developed an innovative, non-invasive technique to detect signs of burns on fossilized bones. Kolska Horwitz explained that standard methods are expensive and destructive, requiring the grinding of bone samples.
“The idea was to develop a method that’s quick, cheap, and can also be run by people working in the field in a small field station,” she stated. This new method, which uses luminescence to detect burning, involves applying a substance to the bone, waiting for a reaction, and examining it under UV light where burnt areas glow white. This development represents a collective effort to create accessible tools for scientific labor worldwide.
Kolska Horwitz, who has worked at Wonderwerk for over 20 years, expressed hope that other researchers globally will adopt this method, potentially leading to more discoveries about early prehistoric fire use. The dating of the site itself was a collaborative effort, primarily carried out by an Israeli team from the Hebrew University and the Geological Survey of Israel.
Tools for Understanding Our Past
Scientists employed paleomagnetic dating, a standard method in Earth sciences that relies on changes in Earth’s magnetic field, using sediments in the cave to get a signal of magnetic directionality. They also utilized cosmogenic burial dating, which analyzes quartz grains in sediments to determine when they entered the cave and stopped receiving cosmic radiation.
With the confirmation of fire use close to 1.8 million years ago, archaeologists now plan to investigate the deepest level of the cave’s occupation, dating to two million years ago, for even earlier evidence. This ongoing collective scientific inquiry continues to illuminate the foundational acts of human labor and ingenuity that shaped our species' development.