Aided by archaeological clues from caves used as Stone Age dwellings, a new study tests ancient cave lighting solutions to better understand how early humans lived in these caverns.

Since humans are not physiologically adapted to see in the dark, lighting systems aside from those naturally provided (such as from the sun) were necessary to ensure survival. Furthermore, a source of cave lighting probably helped our ancestors develop social and economic behavior during the Paleolithic ages.

This follows the humans' discovery and subsequent control of fire, allowing the first symbolic behavior in deep caves some 176,000 years ago. The new inquiry on cave lighting methods in the Stone Age appears in the journal PLoS ONE, in a report titled "The conquest of the dark spaces: An experimental approach to lighting systems in Paleolithic caves."

Traditional Indian Diya, One of the Oldest Lighting Systems
(Photo: Kumar83 via Wikimedia Commons)

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An Experimental Study on Cave Lighting

The research team was led by Mª ángeles Medina-Alcaide, from the Department of History at the University of Cordoba and the International Institute for Prehistoric Research of Cantabria (IIIPC) both in Spain. Together with her colleagues, the team used archaeological clues of lighting found from different Paleolithic caves in Southwestern Europe that feature some cave lighting. They then experimentally recreated these artificial lighting systems and analyzed them qualitatively and quantitatively - conducting their experiments n the Isuntza I Cave in the Basque region of Spain.

As much as possible, they made their experimental lighting systems on archaeological evidence to be as authentic as possible. They used five torch replicas using ivy, oak, birch, juniper, and pine resins as ingredients; two stone lamps fueled by animal fat, taken from cows and deers' bone marrows; and a small fireplace made from juniper wood and oak.

Different Cave Lighting for Different Purposes

Researchers discovered that all three cave lighting systems had diverse features, which suggests that there were varying contexts and purposes for the use of each. For example, wooden torches made from different sticks lit together worked especially well for exploring dark caves or crossing wide spaces since they projected light in all directions. Depending on the material, these recreations of paleolithic torches gave off light for up to 6 meters. Additionally, these torches were easy to transportable and didn't blind or dazzle the bearer with their light, despite being five times brighter than the double-wicked grease lamp.

Stick torches also lasted for an average of 41 minutes, with the experiments lasting from 21 minutes to 61 minutes. However, the torches were not consistent in giving off light, requiring close supervision from the bearer when they're lit. They were, however, easy to relight by oxygenation or allowing them to absorb oxygen by lightly swinging the torch.

The main disadvantage of the stick torches, according to the researchers, was in the amount of smoke they produced.

On the other hand, keeping small sections of the cave illuminated was a job best done by grease lamps. Giving off as much light as a candle can light up to three meters, which can be increased depending on the number or volume of the wick used. In contrast to the torch, grease lamps lit consistently and without much smoke. They were, however, unsuitable for cave lighting while moving due to their dazzling tendencies for the user, as well as their poor floor illumination.

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