An enlightening new study conducted by prehistoric archaeologists from Tel Aviv University in Israel has revealed how early humans cave dwellers who lived 150,000 to 170,000 years ago managed the fires they set inside caves.
For the purposes of their study, which was just published in the journal Scientific Reports , researchers Yafit Kedar, Gil Kedar, and Ran Barkai used archaeological data collected from Lazaret Cave in France, a well-explored site that was first occupied by early humans during the Lower Paleolithic period .
Excavations at the cave proved that these cave dwellers had chosen to place their community hearths in the same general location over and over again across the centuries. This suggested they were choosing that location for logical reasons, rather than just building their fires randomly.
Through their work, the Tel Aviv University researchers were able to verify this theory. Early human cave dwellers chose hearth sites that reflected a knowledge of fire’s characteristics and properties. They built their fires in a particular spot in order to maintain a comfortable and livable indoor environment, where they could reside safely and securely in all types of weather conditions.
Excavations at the Lazaret Cave, France. (De Lumley, M. A. / Public Domain )
Where There’s Smoke, There’s Fire—and Vice Versa
For early cave dwellers the hearth functioned as a primary gathering place. Members of hunting-gathering groups who’d chosen a cave residence would rely on a well-tended and sustained fire to provide them with warmth and light. They would cook all of their food over their cave fires, and use the intense heat to shape or harden their flint tools . A hot and roaring fire would help keep potentially dangerous animals away, making the cave environment safer for humans to occupy.
But cave dwellers couldn’t just put their hearth anywhere. They had to start their fires in a location where ventilation was good and the smoke would disperse as rapidly and efficiently as possible. If the smoke was too dense near the fire, they could have experienced serious respiratory issues and other health problems.
But did early humans actually possess the cognitive abilities necessary to make the best decisions about where to set their cave fires? That is what the Tel Aviv University scientists were anxious to find out.
In the past, the only way to study smoke flow patterns inside a cave would have been to go there and set fires in different locations, and then take measurements to find out where the smoke was going. Such an approach would of course have been impossible, since it would have irreparably damaged sensitive archaeological sites.
Fortunately, modern technology has alleviated the need for such extreme (and impossible measures). Using a software-based smoke dispersal simulation model to recreate such activity, the Tel Aviv University scientists were able to calculate precise smoke exposure levels throughout the cave for 16 hypothetical fire locations.
Smoke dispersal in a cave. Smoke is emitted towards the ceiling in the direction of the cave opening. The arrows represent air circulation, and the broken line represents the balance point between the cold and hot air flows. (Kedar, Y. & Barkai / Nature)
Running through all of these calculations, the researchers identified a section of the cave that would have made an ideal location for a sustained fire. If a community hearth were placed in this area, people would be able to huddle or sleep next to the fire for as long as they wanted without having to worry about unsafe or uncomfortable levels of smoke exposure. This section comprised less than 10 percent of the cave’s 3122 square feet (290 square meters) of available floor space, and was located near the cave’s center.
To the researchers delight, this section coincided perfectly with the location of the hearths that had been identified in Lazaret Cave’s various excavation layers.
The scientists’ model predicted that the lowest smoke density in the cave as a whole would be achieved by placing the fire at the back of the cave. But if that had been done, the smoke would have accumulated around the fire enough to make its immediate vicinity unpleasant to inhabit. In other words, people would have had to stay too far away from the fire to benefit from the warmth and light it was producing.
“Early humans needed a balance—a hearth close to which they could work, cook, eat, sleep, get together, warm themselves, etc. while exposed to a minimum amount of smoke,” Yafit and Gil Kader explained in a Tel Aviv University press release . “Ultimately, when all needs are taken into consideration—daily activities vs. the damages of smoke exposure—the occupants placed their hearth at the optimal spot in the cave.”
Optimal, in the sense that smoke density was not the lowest possible, but the lowest consistent with the need of the people to stay close to the fire for extended periods of time, without suffering from dangerous levels of smoke inhalation.
Survival as a Motivation for Learning
It should be noted that simple trial-and-error procedures wouldn’t have been sufficient to determine the prehistoric fire builders’ final choice of hearth location. If this had been the case, the archaeological record would have revealed evidence of fires started in many locations in each layer, as the trial-and-error process proceeded. What it shows instead is the consistent choice of the same general location, meaning the fire makers must have known exactly what they were doing and why.
This new innovative research from Israel makes it clear that early humans understood how to work with fire in enclosed environments, where managing them thoughtfully and carefully would have been necessary to achieve the desired results. This reveals important details about the thinking and learning patterns of early humans, giving scientists greater insights into their true level of intelligence.
“Our simulations of smoke density at Lazaret Cave clearly show that Lower Paleolithic humans in this cave were able to choose the perfect locations for their hearths,” the archaeologists wrote in their Scientific Reports article. “This ability is the reflection of experience, ingenuity, and planned actions. The acquaintance of early humans with the effects of operating a hearth inside Lazaret cave is nothing short of astonishing, as are the clever and thoughtful considerations that went into organizing the space inside the cave.”
Fire was essential to survival for Lower Paleolithic humans. This gave them great motivation to learn how to manage it as precisely and intelligently as possible.
Top image: Reconstruction of ancient human cave dweller in the Lazaret Cave, France, showing the hearth at the side of the cave. Source: De Lumley, M. A. / Public Domain
By Nathan Falde