A Brilliant Experiment Demonstrates How Our Forefathers Used Lighting Sources in Caves
Humans lived in and explored caves in quite different ways tens of thousands of years ago than we do today. While they may not have had access to modern flashlights, this does not mean they lived in total darkness.
To gain a better understanding of ancient cave-dwelling life – from rock art painting to social interaction – a team of academics has replicated three popular forms of old illumination techniques: torches, grease lamps, and fireplaces.
All three were utilized in the Upper Paleolithic period, some 50,000 years ago; the scientists then tested their lights in the Isuntza 1 Cave in Spain.
“Humans [..] need light to enter the deep parts of caves, and their visits to those places depend on the physical characteristics of their lighting systems,” the researchers wrote in their article.
“The luminous intensity, radius of action, type of radiation, and color temperature of the light determine the perception of the environment and the human use inside (such as the execution of art, funerary activities, and cave exploration).”
The researchers wore eight different lights inspired by prehistoric artifacts: five torches composed of ivy, juniper, oak, birch, and pine resins, two stone lamps burning animal fat (cow and deer bone marrow), and a small, static fireplace constructed of oak and juniper wood.
Inside the cave network – two larger open spaces and a tunnel – measurements were made of the brightness of each illumination source, its duration, and the temperatures generated.
The torches fashioned from hardwood sticks appeared to be the finest for exploring and maneuvering: they lasted a reasonable amount of time (on average 41 minutes), radiated light in all directions (nearly six meters or 20 feet), and could be readily relit by waving them from side to side. They did, however, generate a great deal of smoke.
The grease lamps were the most effective at illuminating tiny rooms for an extended period of time, burning for nearly an hour without emitting much smoke – however their light only extended approximately half as far as the torches’ light.
The fireplace, on the other hand, had to be extinguished after 30 minutes due to the amount of smoke it produced — despite the fact that it illuminated a distance of 6.6 meters (21.7 feet). According to the researchers, the fire would need to be located in an area with adequate ventilation or be large enough to generate its own convection currents.
These studies provide insight into the limits that humans in the Upper Paleolithic faced when it came to tunnel exploration, living in deeper caves, and even generating cave art.
According to Ars Technica, some experts believe that ancient cave art was purpose-built for a flickering, uneven source of illumination – and may even have been painted to create the sense of movement when the light fluctuated.
That is not a feature included in this new study, but the scientists did run a simulation using their illumination measurements to determine how these torches, lamps, and fireplaces would perform in Spain’s Atxurra cave, which is famous for its Paleolithic-era artworks.
Static fireplaces appear to have been required to illuminate all of the cave art, as light from torches and lights would not have reached far enough.
The researchers behind the new study believe that this is only the beginning of this type of investigation – additional types of lighting sources and fuels can be tested and simulated in additional types of environments to gain a better understanding of how our forefathers and mothers spent their time in caves.
“Our experiments on Paleolithic lighting point to planning in the human use of caves in this period and the importance of lighting studies to unravel the activities carried out by our ancestors in the deep areas of caves,” the researchers write.
The study was published in the journal PLOS One.