A cave in France that was used by Neanderthals – or possibly their ancestors – may contain the oldest direct evidence of controlled fire use by humans in Europe. While it’s currently unclear exactly which species of ancient hominid lit these prehistoric campfires, the discovery suggests that our lineage had developed the ability to ignite flames at will by 270,000 years ago.

Reporting their findings in a yet-to-be-published study – which is currently undergoing peer review – researchers explain that retracing the use of fire in the distant past is notoriously challenging. For one thing, it’s often impossible to determine whether charred artifacts were burnt by anthropogenic – or human-made – fires or natural blazes. Even where evidence for deliberate fire use is strong, there’s often no way of knowing if the inferno was ignited deliberately or opportunistically, such as by carrying burning sticks or embers from elsewhere in the landscape.

So while there is a wealth of evidence to suggest that fire was used at human sites from about 1.6 million years ago, determining when exactly we learned to control the element is something that continues to keep anthropologists up at night.

Hoping to throw some light onto the subject, the study authors turned their attention to a cave in southeast France called Orgnac 3, which was inhabited by humans during the Early and Middle Stone Age, long before Homo sapiens arrived in Europe. Intriguingly, a number of hearths have been identified in the cave, and researchers recently discovered a sooty speleothem – or mineral formation – which indicates the presence of fire within the cavern at some point in the past.

Using a modern dating method called fuliginochronology, the study authors were able to recreate the history of fire use at Orgnac 3, discovering that between 23 and 27 fires were lit over the course of a millennium some 270,000 years ago. Based on this finding, the hearths may have been used by Neanderthals or their most recent common ancestor with our own species, known as Homo heidelbergensis.

Overall, it’s clear that the cave fires were not lit on a daily basis, although the frequency of flames within the cave does suggest that someone was periodically returning to ignite a campfire every few decades. Furthermore, the fact that these fires occurred so deep within a cave immediately hints at the fact that they were lit by people rather than natural events like lightning strikes. 

Previously, the earliest evidence of repeated, controlled fire use had come from a cave in Spain, where hearths may have been lit some 245,000 years ago. If the authors of this new study are correct, then humanity’s mastery of fire began at least 25,000 years earlier than that.

And yet, the researchers can’t be entirely sure that these fires were controlled or ignited from scratch, rather than made from flames harvested from natural forest fires. However, further analyses revealed that 52 percent of these fires coincided with wet periods, when natural blazes were unlikely to spread through the local landscape, therefore suggesting that the cave fires were probably lit in situ using some kind of pyrotechnology.

“Given the evidence of human activity, the environmental conditions, the enclosed nature of the site, and the association of soot films with microsparite deposits formed during wet periods, the most likely and parsimonious hypothesis is that the soot traces in [Orgnac 3] are indeed remnants of anthropogenic fire,” write the study authors.

“Therefore, this study provides strong evidence of fire mastery among Mid-Pleistocene hominins,” they conclude.

The study is currently available as a pre-print on Research Square.