Revolutionary method to establish the time between Neanderthal fires

A study develops a revolutionary method to establish the time between Neanderthal fires



Santiago Sossa-Ríos, from the Universitat de València, excavating a hearth at El Salt. Photo: Sven Kleinhapl.

The interdisciplinary research team from the Universitat de València, the University of Burgos, the University of La Laguna, the University of Alacant, the Complutense University of Madrid and the Institute of Geosciences has succeeded in determining with high precision the time between different Neanderthal fires at El Salt site (Alcoi, Alicante). The research is published in the journal Nature, and addresses one of the greatest challenges in prehistoric archaeology: the timescale of human activity in the Palaeolithic. This achievement was made possible by the study of fires or ’hearths’ and their archaeological remains, using an innovative methodology that combines archaeomagnetic and archaeostratigraphic analyses.

The results of the study show that the hearth sequences were formed over a minimum time span of about 200’240 -years, with decades between some of them. This is an unprecedented temporal resolution with important archaeological implications. The temporal sequence implies that the different human groups that made the fires were separated by different generations. This technique represents a major step forward in archaeology, and it will help to better understand human behaviour in the past.

Researcher of Prehistory, Archaeology and Ancient History Santiago Sossa-Ríos believes that the study is crucial to understand that the problem of time in prehistory is still very much open: ’When excavating archaeological settlement areas, we assume that they are the result of many events of human activity, but until now we did not know exactly how much time. We did not know whether it was decades, hundreds or thousands of years. But now we know that at least decade-long intervals took place between some of them.’ Sossa-Ríos explains that this study opens up doors to reaching important conclusions using the common element in Palaeolithic site that is fire. ’From there, within this temporary framework, we can open up new lines of investigation to study, for example, mobility patterns, technological changes or differences in the use of space. Time is there, the challenge is to combine and to extract everything that the methods offer us to get there’, says the researcher from the Universitat de València.

The study was executed throughout almost 10 years, and analyses a sequence of six hearths from the same archaeological unit (Unit X), dating back around 52,000 years. The cave of El Salt is a Neanderthal site, best known for the existence of several well-preserved hearths. These hearths can be on the same surface or separated by a few centimetres of sediment, and they are associated with several stone tools and bone and coal fragments from different periods of human activity. Until now, no one knew the order and time between these different hearths and activity remains, which are common in the worldwide Palaeolithic record. This has made the study of prehistoric societies much more difficult. The study determines that the set of hearths covers at least around 200’240 -years with 99% a probability, with decades between some of them. This is an unprecedented resolution in Palaeolithic archaeology and significantly alters previous ideas about the frequency of the human activity in prehistoric hunter-gatherer societies.

Until now, the available dating techniques for such ancient contexts such as El Salt Unit X have had large temporary uncertainties. In the recent investigation, the stratigraphic position of the hearths and remains was inferred through archaeostratigraphic studies. Once the stratigraphic order of the hearths was inferred, the minimum time between fires was estimated. This is the main methodological result of the study. For this purpose, archaeomagnetism was used. This is the geophysical discipline that studies the register of the direction and/or intensity of the Earth’s magnetic field (EMF) in burnt archaeological materials.

The results

In the case of El Salt Unit X, the results obtained have very important and unexpected implications. The hearths that were distributed in centimetre-thick layers of sediment or on the same surface represent at least two centuries. This discovery questions the usual archaeological practice of studying materials as belonging to a single cultural group or period of human life, and encourages researchers to reconsider their approach.

The fact that the hearths were formed over a minimum time span of about 200’240 -years implies that human groups were separated by generations. There were people who may not have even met each other. The archaeological implications are huge. We must not forget that these were hunter-gatherer groups, constantly on the move in search of resources. The excavation of this site is only an isolated and concrete image of a whole ensemble of activities in a much larger area. These results are small photograms from a very long film, but their temporal context has been achieved with high precision. Furthermore, this is a method that can be applied not only to Palaeolithic chronologies, but also to any period that has well-preserved combustion structures. ’It is definitely a major step forward in archaeology, which will help us to better understand human behaviour in the past’, explain the authors of the study.

Reference:

Herrejón-Lagunilla, Á., Villalaín, J.J., Pavón-Carrasco, F.J. et al. The time between Palaeolithic hearths. Nature (2024). https://doi.org/10.1038/s41586­’024 -07467-0