Chronological constraint of Neanderthal cultural and environmental changes in southwestern Europe: MIS 5-MIS 3 dating of the Axlor site (Biscay, Spain)

First published: 08 May 2023. OnlinePublThe cave site of Axlor (Biscay, Spain) preserves one of the most informative Middle Palaeolithic (MP) records for the North Atlantic Iberian region, though its age remains poorly known. Here we use single‐grain optically stimulated luminescence (OSL) and single‐grain thermally transferred OSL (TT‐OSL) dating of sediments to improve the age constraint of Axlor's MP succession (levels N–B). Our new ages are consistent with the previously published terminus ante quem 14C ages for the site (>42.9 cal ka BP), and suggest the sequence accumulated during a period of ~50 kyr. Axlor's levels N–F were deposited ~100–80 ka, probably during marine isotope stage (MIS) 5d–a, while levels D and B were deposited ~70 and ~50 ka, respectively, during MIS 4 and mid‐MIS 3. Our results indicate that major faunal and technological turnovers occurred towards the end of MIS 5, potentially coinciding with broader environmental and climatic changes. Axlor's Quina record, dated here to the onset of MIS 4, is one of the oldest in Europe. Comparisons with neighbouring sites point to complex regional chronologies and development for this particular behaviour, though detailed correlations with other MP sequences remain difficult due to their poor chronological attributes. The present study highlights the important role that single‐grain optical dating can play in elucidating the broader evolution of the MP across southwestern Europe.Martina Demuro, Lee J. Arnold, Jesús González, Urquijo, Talia Lazuen and Manuel Frochos

Identifying Experimental Tool Use Through Confocal Microscopy

Characterizing use-wear traces quantitatively is a valid way to improve the capacity of use-wear analysis. This aim has been on specialists’ agenda since the beginning of the discipline. Micropolish quantification is especially important, as this type of trace allows the identification of worked materials. During the last decade, confocal microscopy has been used as a promising approach to address this question. Following previous efforts in plant microwear characterization (Ibáñez et al. Journal of Archaeological Science, 48, 96–103, 2014; Journal of Archaeological Science, 73, 62–81, 2016), here we test the capacity of the method for correctly grouping experimental tools used for working eight types of materials: bone, antler, wood, fresh hide, dry hide, wild cereals, domestic cereals, and reeds. We demonstrate, for the first time, that quantitative texture analysis of use-wear micropolish based on confocal microscopy can consistently identify tools used for working different contact materials. In this way, we are able to move toward using texture analysis as part of the standard functional analysis of prehistoric instruments.This study is part of the projects HAR2016-74999-P, HAR2015-68566-P, and HAR2016-81971-REDT funded by the Spanish Ministerio de Ciencia, Innovación y Universidades.Peer reviewe

How grinding evolves

An experimental set-up has been devised to monitor mechanochemical processes in situ, yielding direct insights into mechanistic and kinetic aspects of solid-state reactions that are promoted by grinding, such as the synthesis of metal–organic frameworks