Alfonso Benito Calvo, a geologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), is part of the international team that has just published a paper in the journal Nature Communications about the work at the Guefaït-4 site in Morocco, and this has made it possible to reconstruct the ecological context of northern Africa 2.5 million years ago. 

Through the multiple analyses conducted, this multidisciplinary research team has been able to show that this area had a diversity of environments where aridity was the dominant ecological context, but there were forested areas, wetlands and more open spaces. This paleoecological information is very important for understanding the evolution of Plio-Pleistocene hominins in northern Africa and comprehending their adaptive capacity to the changing and ever more open environments we find in the African continent at this period. 

This is the principal conclusion of this work led by Iván Ramírez-Pedraza, an FI Agaur Grant researcher at the IPHES-CERCA, and the other participants were researchers from the Universitat Rovira y Virgili (URV), the Faculty of Sciences of the Mohamed I University of Oujda (FSO, UMP), Max Planck Institute of Geoanthropology, Universitat Autònoma de Barcelona (UAB), Bryant University (USA), Consejo Superior de Investigaciones Científicas (CSIC-Junta de Extremadura), University of Iceland, Museo Nacional de Ciencias Naturales (MNCN), University of the Phillippines, Institut National des Sciences de la Arqueología et du Patrimoine (INSAP), and the Histoire Naturelle del Homme Préhistorique (MNHN/CNRS/UPVD), in addition to the CENIEH.

According to the lead author, “our results offer the first ecological framework known for northern Africa, where we did not previously have robust, tightly constrained data, unlike other parts of the continent such as the east and south."

These data were obtained by applying well-tested and complementary analytical techniques. The main techniques were the analysis of stable isotopes and the dental wear on the faunal remains of large vertebrates recovered at the Guefaït-4 site. 

Firstly, isotopic studes of dental enamel furnished information about the types of food ingested and the temperature of the water taken. Secondly, the authors conducted an analysis of the dental microwear: this consists of quantifying a series of marks such as scratches and pits, formed on the tooth surface while food is being consumed.

In addition to these analyses, they also carried out pollen studies, and analyzed the isotopes in the wax of the plants found in the sediments, identifying the different species of micromammals, microcrustaceans and algae at the site.

Expansion of the hominins 

The stratigraphic studies performed at the CENIEH have made clear that the site was generated during a more humid phase which fostered the formation of lagoons at the foot of the mountains, and it was here that sludges and carbonates that permitted the fossilization and preservation of the faunal remains accumulated.

The period between the Pliocene and the Pleistocene (Plio-Pleistocene transition) is when the glaciations in the northern hemisphere and a global trend toward aridity got under way. Thanks to this work now published, we know that this aridity was also present locally, but it formed part of a very diverse ecosystem. This regional mosaic environment, combined with moments during the transition cited when the Sahara greened, could have facilitated the dispersion of communities of mammals (including hominins) from central or eastern Africa toward the north of the continent, occupying ecosystems where the availability of resources was similar to that in their original habitats.

The evidence for the earliest hominins in northern Africa has been dated to around the Plio-Pleistocene transition (about 2.5 million years ago) at the Ain Boucherit site in Algeria. The ecological context for this first population is a key question for understanding how our ancestors and other mammals dispersed through this territory. “If we consider how close together Guefaït and Ain Boucherit are, knowing the ecology of such a large territory can offer us clues to the ecological resources these first hominins could have availed of,” explains M. Gema Chacón, a researcher at the IPHES-CERCA, who is also codirector of the project along with Dr. Robert Sala Ramos, a professor at the URV, and Hassan Aouraghe, a professor at the UMP.

An international undertaking

Since 2006, the Aïn Beni Mathar-Guefaït Basin has been the object of a research project directed by Sala Ramos, Chacón, of the Institut Català de Paleoecologia Humana i Evolució Social (IPHES-CERCA), and Aouraghe, of the Faculty of Sciences of the Mohamed I University in Oujda (Morocco). Its main objective is to investigate the origins of the humans who settled in northern Africa.

The project enjoys the collaboration of the government of the province of Jerada, the local authorities of Aïn Beni Mathar i Guefaït, and Mohamed I University in Oujda (Faculty of Sciences), the Ministry of Youth, Culture and Communication of the Kingdom of Marruecos, and the Institut National des Sciences de l'Archéologie et du Patrimoine (INSAP), also in Morocco. This research is financed by the Agencia Estatal de Investigación (Ministerio de Ciencia, Innovación y Universidades), the CERCA program (Generalitat de Catalunya), the Fundación Palarq, the Ministerio de Cultura y Deporte, the Ministerio de Ciencia, Innovación and Universidades, the María de Maeztu program (CEX2019-000945-M), and is also supported by the activities of the Research Groups (SGR) of the Generalitat de Catalunya, among others.