On the age of Ain Hanech Oldowan locality (Algeria): First numerical dating results

Our current understanding of early human settlements in North Africa relies on a few well-contextualized Oldowan and Acheulean sites (e.g., Ain Hanech, El Kherba, Ain Boucherit Lw and Up, Tighennif in Algeria; Thomas Quarry in Morocco). In particular, the site of Ain Hanech has documented for many decades the earliest evidence of human presence in North Africa (e.g., Sahnouni and de Heinzelin, 1998), until older stone tools were recently reported at the nearby Ain Boucherit locality (Sahnouni et al., 2018). While the Early Pleistocene antiquity of this Oldowan assemblage has never really been questioned, its exact age has, however, been discussed. In the early 2000s, a series of articles were published in this journal arguing either for an age of ~1.8 Ma (Sahnouni et al., 2002, 2004) or much younger, around 1.2 Ma (Geraads et al., 2004). Although subsequent chronostratigraphic studies have provided additional evidence for the older age (Pares et al., 2014 ; Sahnouni et al., 2018; Duval et al., 2021), Ain Hanech site had never been numerically dated until now. Moreover, beyond the archeological relevance of the site, Ain Hanech faunal association has also long been used as a reference for biochronological inferences and comparative studies with other paleontological localities of the region (e.g., Geraads, 2002; Sahnouni et al., 2002; Van der Made and Sahnouni, 2013; Van der Made et al., 2021). In other words, the accuracy of North African biochronology over the Early Pleistocene timescale partly relies on the age of Ain Hanech. In this context, we present here the dating results from electron spin resonance (ESR) and uranium-series (U-series) methods tentatively applied to optically bleached quartz grains and fossil teeth from Ain Hanech and the nearby stratigraphically equivalent site of El Kherba (Sahnouni and de Heinzelin, 1998).