Archaeological discoveries

Did Paleolithic men use fire to give life to their engravings?

Stone plates discovered on a Paleolithic site in the south of France, which bear engravings of animals or anthropomorphic forms, questioned a team of researchers on their function. They suggest that these stones were used to create some sort of lively nighttime spectacle through fire.

Photograph showing ambient light levels and the position of the platelet replicas relative to the fire during the researchers' experiment.

What could our ancestors be doing 15,000 years earlier, when evening was falling? The discoveries made at the Montastruc site (France) provide an overview. The artifacts found date to the Magdalenian, an Upper Paleolithic cultural era that spans 17,000 to 14,000 BCE. It was for Homo sapiens a period rich in the production of portable or parietal art in Western Europe, over a geographical area stretching from Portugal to Germany. Among these finds, engraved stone plaques have attracted the attention of researchers regarding their use:were they functional, decorative or ritual? This study, published in PLOS One on April 20, 2022, brings a new way of understanding European Paleolithic art.

Enigmatic engraved stones

In the middle of the 19th century, Peccadeau de l'Isle, an archaeologist, discovered around fifty limestone slabs in Montastruc, a town in the south-west of France. They were exhumed from a limestone shelter 29 meters high, near the Aveyron River, which was a place occupied by human societies around 15,000 years ago. They are covered with engravings of animals (horses, reindeer, ibexes, cattle), anthropomorphic shapes and abstract patterns, sometimes intertwined with each other. For almost two centuries, these plaques were kept in the British Museum as artistic artefacts from the Paleolithic era.

Recently, a team of archaeologists wanted to analyze them thoroughly, despite an important shortcoming:the context of discovery of these plates is too old and not precise enough. Without an idea of ​​their original location in the shelter, of their depth of burial when they were discovered, the interpretation of their function is all the more speculative. The analysis of these platelets using digital technologies nevertheless revealed clues. Radiocarbon dating of two of them concludes that they were made between 16,000 and 13,500 years before present, their homogeneity suggesting an in situ deposit .

A close connection with fire

Thanks to an arsenal of techniques such as microscopy, 3D modeling and virtual reality, it was possible to see that these wafers had been weakly exposed to light, but also that the majority of them bear traces of heating. It is likely that they remained in the shelter and near a fireplace with low ambient light. Several are cracked or bear thermal fractures, as well as traces of pinkish discoloration that show they have been burned. This is the phenomenon of reddening:the stone takes on a red color when it has been heated between 100°C and 300°C. Above 600°C, the stone takes on a light gray tint.

According to the team, this platelet burning activity could be unique to Montastruc. Several assumptions are made:

What could our ancestors be doing 15,000 years earlier, when evening was falling? The discoveries made at the Montastruc site (France) provide an overview. The artifacts found date to the Magdalenian, an Upper Paleolithic cultural era that spans 17,000 to 14,000 BCE. It was for Homo sapiens a period rich in the production of portable or parietal art in Western Europe, over a geographical area stretching from Portugal to Germany. Among these finds, engraved stone plaques have attracted the attention of researchers regarding their use:were they functional, decorative or ritual? This study, published in PLOS One on April 20, 2022, brings a new way of understanding European Paleolithic art.

Enigmatic engraved stones

In the middle of the 19 e century, Peccadeau de l'Isle, an archaeologist, discovered about fifty limestone slabs in Montastruc, a town in the south-west of France. They were exhumed from a limestone shelter 29 meters high, near the Aveyron River, which was a place occupied by human societies around 15,000 years ago. They are covered with engravings of animals (horses, reindeer, ibexes, cattle), anthropomorphic shapes and abstract patterns, sometimes intertwined with each other. For almost two centuries, these plaques were kept in the British Museum as artistic artefacts from the Paleolithic era.

Recently, a team of archaeologists wanted to analyze them thoroughly, despite an important shortcoming:the context of discovery of these plates is too old and not precise enough. Without an idea of ​​their original location in the shelter, of their depth of burial when they were discovered, the interpretation of their function is all the more speculative. The analysis of these platelets using digital technologies nevertheless revealed clues. Radiocarbon dating of two of them concludes that they were made between 16,000 and 13,500 years before present, their homogeneity suggesting an in situ deposit .

A close connection with fire

Thanks to an arsenal of techniques such as microscopy, 3D modeling and virtual reality, it was possible to see that these wafers had been weakly exposed to light, but also that the majority of them bear traces of heating. It is likely that they remained in the shelter and near a fireplace with low ambient light. Several are cracked or bear thermal fractures, as well as traces of pinkish discoloration that show they have been burned. This is the phenomenon of reddening:the stone takes on a red color when it has been heated between 100°C and 300°C. Above 600°C, the stone takes on a light gray tint.

According to the team, this platelet burning activity could be unique to Montastruc. Several assumptions are made:either it is a fortuitous burning of these chips, or they were purely functional (as an oven structure or boiling stone for example), or it was a non-functional activity, perhaps - be artistic. "The study is innovative because it brings together several levels of tools and techniques with an experimental input, which allows a rather complete analysis of these platelets ", note to Sciences et Avenir Oscar Fuentes, archaeologist at the National Center for Prehistory. "It comes in addition to other work such as that of Catherine Ferrier on the experiments of heating the walls of caves and the similar phenomena that emerge ."

Dramatic color changes

During an experiment at the York experimental archeology research centre, the research team placed limestone slabs similar to those found at Montastruc under real conditions, near a fire. Some were at a medium distance from the hearth, others very close to the flames. They observed that the stone showed "spectacular color changes "when the limestone was heated, particularly at the level of the engraved parts, and which corresponded to the reddening temperatures recorded on the Montastruc slabs. The researchers concluded that it was possible to witness different visual effects caused by the variations of light intensity of the fire.

The following video shows the VR simulation of plate no. 662, which offers a good example of the effect of these overlapping engravings in the light of a fire. Depending on the angle of positioning relative to the focus, some ibex engravings are more highlighted.

Video of wafer #662 in VR lighting simulation, oriented in two different directions. ©Andy Needham &all / PLOS One, 2022

The researchers noted that the wafers placed near the fire produced "notable visual effects (...) by shimmering on the etched surface ", adding dynamism to the various patterns. The effect was "particularly remarkable for the overlapping engravings ", seeming to come alive under the effect of the flames. "The study of the relationship between manipulable engraved stones and their visual effect against the light of a hearth is relatively innovative , continues Olivier Fuentes, there is not much work on this aspect. It is quite probable that this type of platelet was used in this way, but this can only be confirmed by supporting this hypothesis by studying other corpora exhumed on other sites, in particular engravings presenting animals stacked or with several pairs of legs ."

A voluntary staging

It is very likely for archaeologists that this is a desired effect. According to them, human neurology would be perfectly suited to interpret changes in light and shadow as movements, not to mention the influence of pareidolia. This assumes that these societies were experts in observing local wildlife, a recurring theme in their artistic production. These are, for the researchers, conditions conducive to the "triggering of visual psychological responses ", the light being able to believe in the illusion of a movement. If the results do not exclude other causes of these traces of heating, the intentional placement of these pads is very likely. The team notes that it there were also plates that have no traces of heating, no doubt used as decorative or ornamental objects.

Olivier Fuentes calls for caution on these interpretations:"We don't know the context in which these plates were found, in fact my feeling is mixed with regard to the results. The use of firelight on parietal engravings is already known, but concerning mobile plates, their multiple possibilities of use do not allow to ensure their main function. Montastruc is difficult to study from this point of view. The study could have mentioned in particular that the reddening of the stones was sometimes intentional, in order to make the whiteness of the engraving even more visible. This has been observed at the prehistoric site of La Marche, in Vienne, where stones were rubbed and re-engraved several times to "refresh" the whiteness of the patterns. "