New study develops revolutionary method for establishing time between Neanderthal fires
Santiago Sossa-Ríos, from the Universitat de València, excavating a hearth at El Salt. Photo: Sven Kleinhapl.
The interdisciplinary team of researchers 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 the El Salt site (Alcoi, Alicante). The study, published in the journal Nature, addresses one of the greatest challenges in prehistoric archaeology - the timeline of human activity in the Palaeolithic period. 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 period of about 200’240 -years, some with decades having passed between them. This is an unprecedented temporal resolution and has important archaeological implications. The temporal sequence implies that there was a generational separation between the different human groups who were responsible for the fires. This technique represents a major step forward in archaeology, and it will help us to better understand human behaviour in the past.
Santiago Sossa-Ríos, a researcher in prehistory, archaeology and ancient history, believes that the study is crucial to the understanding that the problem of time in prehistory is still very much open for debate. ’When we excavate 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 had passed between these activities. We did not know whether it was decades, centuries 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 the door to drawing important conclusions using a common element of Palaeolithic sites - fire. ’From there, within this temporary framework, we can open up new lines of investigation to study, for example, patterns of mobility, technological change or differences in the use of space. The time is there, the challenge lies in combining and extracting everything that the methods offer us to uncover it’, says the Universitat de València researcher.
The study, which was conducted over a 10-year period, analysed a sequence of six hearths from the same archaeological unit (Unit X), dating back around 52,000 years. The El Salt cave is a Neanderthal site, best known for the existence of several well-preserved hearths. These hearths either appear on the ground’s surface or lie just beneath it, separating one from another by a few centimetres of sediment. Many stone tools, as well as bone and coal fragments have also been found here from different periods of human activity. Until now, the timeline of these hearths and remains of this human activity, common throughout the Palaeolithic world, has remained unknown, making the study of prehistoric societies much more difficult. The study determined, with 99% probability, that the set of hearths took place over a minimum of 200’240 -years with decades between some of them. This is an unprecedented resolution in Palaeolithic archaeology and significantly alters previous ideas about the frequency of human activity in prehistoric hunter-gatherer societies.
Until now, the available techniques for dating such ancient contexts such as the 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 registration 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, distributed in centimetre-thick layers of sediment or at the ground’s surface represent at least two centuries. This discovery challenges 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 peroid 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.
