Reacción a "Hominids used fire more than 700,000 years earlier than previously estimated, according to a study involving Spanish researchers"

This is a study of great interest to global prehistory, as it addresses one of the most significant topics for humanity: fire. María Dolores Marín-Monfort and her collaborators propose a significant shift in the current paradigm regarding its use, pushing its origins back by some 800,000 years and situating it 1.8 million years ago in a South African cave, Wonderwerk, which, notably, already housed the previous candidates for humanity’s oldest anthropogenic fires.

In my opinion, the most interesting aspect of this study is the introduction of a new rapid and non-destructive protocol, based on stimulating the bone remains with an external energy source. This technique is known as luminescence. It is important to note that one of the worst “enemies” of bone is heat, which significantly alters its composition. These changes are reflected in how the bones respond to exposure to a special, very powerful blue light: burned bones glow differently than unburned ones, which is key to distinguishing them.

The authors have applied this new methodology to the bones of small animals that were part of pellets—that is, the undigested and regurgitated remains of the prey of nocturnal birds of prey. The results show that, in the Wonderwerk Cave (1.8 million years old), many of the bones comprising these pellets are burned. Thus, the proposal by the research team, led by the National Museum of Natural Sciences in Madrid, is that humans were responsible for using these natural pellets as fuel inside this South African cave.

A key point to discuss is the likelihood that the Wonderwerk fires were of natural origin. This is something that occurs more frequently outdoors, where there is a greater amount of plant fuel and ignition sources are present, such as lightning, just as happens today with unprovoked wildfires.

The methodological impact of the article is unquestionable, as the authors make a crucial contribution to the characterization of burned bones in extremely ancient contexts. However, what raises more doubts is the anthropogenic origin of these fires, since there is no direct evidence that humans were involved in their genesis within the cave.

Traditionally, it has been argued that the oldest documented fires were the result of exploiting natural fires. Marín-Monfort and colleagues’ interpretation fits within this framework, though they go a step further: they suggest that our ancestors did not make a completely passive use of the fires, but rather would have brought lit torches from outside into the cave, up to 30 meters deep, to ignite the clusters of pellets.

The researchers have several factors in their favor. First, the location of the remains 30 meters from the current entrance makes it unlikely that the burning material traveled accidentally from the outside. Second, the fact that these fires recur throughout the stratigraphic sequence.

However, to propose a change of such magnitude—with such significant interpretive consequences for global prehistory—I believe more compelling direct evidence related to its functionality (for example, food cooking) would be required. Furthermore, it would have been advisable for the authors to include an experimental section, using hairballs, to assess the total combustion time, the need for refueling, the type of smoke, or toxicity, given that generating a fire in an enclosed, unventilated space can quickly render the air unbreathable.

In conclusion, if the dating (1.8 million years) and, above all, the intentionality of introducing fire into the cave are confirmed, we would be facing a milestone that would change the course of prehistory. Prior to this article, no fires involving human activity of such antiquity had been recognized.

Thus, the origins of one of humanity’s most revolutionary technologies would be rooted deep in time, occurring very close to another major transition that would give rise to the Acheulean technological complex. This not only represented a significant change in the typology and method of carving stone tools but also in the capabilities.