Today the journal eLife publishes the results of a multidisciplinary dating work revealing for the first time that Homo naledi lived between 230,000 and 330,000 years ago in South Africa. Based on the combination of a wide range of methods such as Luminescence, Paleomagnetism, Electronic Spin Resonance (ESR) and Uranium-Thorium Series, this work enables for the first time to obtain a reliable date for this new species discovered and published by the paleoanthropologist Lee R. Berger and his team in 2015.

This new scientific study led by Prof. Paul Dirks from James Cook University involved many researchers from several institutions in Australia, USA, South Africa and Spain, including the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) in Burgos, Spain.

Since the announcement of its discovery in September 2015, several hypotheses have been formulated on the age of H. naledi, based mainly on the archaic morphology of the fossil remains. One of the hypotheses with more weight proposed a very old age, up to 2 million years. However, the new dating undoubtedly points towards a much more recent chronology.

The central point of the work is the direct dating of several human teeth with the ESR method, since it is the only method that can be used for fossil remains older than 50,000 years, the maximum time range covered by the Radiocarbon dating method. Part of this work was carried out in the CENIEH laboratories by Dr Mathieu Duval, a CENIEH researcher, within the framework of a European research project Marie Curie IOF, and in collaboration with Prof. Rainer Grün, director of the Australian Research Centre for Human Evolution (ARCHE) at Griffith University (Brisbane, Australia).

The central point of the work is the direct dating of several human teeth with the ESR method

"In order to obtain a reliable age result without destroying the human teeth, we had to use a special analytical procedure that consists in measuring enamel fragments by ESR in combination with high resolution Laser Ablation ICP-MS U-series analyses. Today, there are probably no more than two or three laboratories in the world where you can apply this cutting-edge protocol", says Mathieu Duval, currently Senior Research Fellow at ARCHE.

The obtained data allow locating H. naledi in a position much more advanced than initially expected in the human evolutionary tree, for example with a more recent chronology than the hominins found in the deposit of the Sima de los Huesos of Atapuerca. "With these new results, we see all the complexity of the human evolutionary tree that is being progressively drawn based on the recent discoveries made over the last years," says Mathieu Duval.

The CENIEH at the forefront in dating

The results of this work demonstrate the major limitations in determining the age of a prehistoric site based on the morphological and/or technological aspects of the fossil remains or lithic industries. Instead, they indicate the need to use the most advanced dating methods to obtain reliable chronologies.

This paper on H. naledi is the most recent one of a series of important works recently published by the Geochronology Research Program of CENIEH, which deal with the dating of relevant prehistoric sites, such as the ancestors of the “Hobbit” of Flores, the Sima de los Huesos fossil record and TD6 level of Gran Dolina, both from Atapuerca (Burgos , Spain), or the archaeological site of Fuente Nueva-3 in Orce (Granada, Spain). According to Prof. Josep M. Parés, coordinator of the CENIEH Geochronology Research Program, "the importance of these dating results recently published undoubtedly position the Geochronology Research Program, and thus the CENIEH, at the forefront in age dating of key prehistoric sites."