Molecular and isotopic analyses on prehistoric pottery from the Virués-Martínez cave (Granada, Spain)

Abstract

The analysis of the organic residues in archaeological pottery usually involves the use chromatography and mass spectrometry techniques. The identification of organic compounds processed in archaeological vessels, which generally degrade over archaeological timescales, provides insights about their origin and uses of the vessels. This paper provides an advance of archaeometric characterization of the organic residues in seventeen pottery vessels from the end of the 4th millennium BCE found in the Virués-Martínez cave (Granada, Spain), using gas chromatography–mass spectrometry (GC–MS), gas chromatography-isotope ratio mass spectrometry (GC-C-IRMS), and ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). To our knowledge this is the first study on the use of UPLC-HRMS on archaeological residues. Despite the fact that the identification of plant remains continues to be elusive, this study demonstrates the potential usefulness of UPLC-HRMS technique to study the polar fraction of plant residues, thus allowing us to formulate more specific hypotheses about the vegetal compounds that have survived in association with the pottery vessels (erucamide, matricarin, piptamine, piceatannol). Our results indicate that the occupants of the cave used the vessels to process plant materials and also degraded animal fats (ruminant fat) and it is very likely that the vessels were used for a variety of purposes, with accumulation of by-products over time, and were not made exclusively for funerary practices. The δ13C values C16:0 and C18:0 fatty acids obtained open a debate on the consumption of dairy compounds in the Iberian Peninsula during the end of the Neolithic and beginning of the Copper Age.