Ancient waterlogged ivory: tracing its origin through DNA analysis and spectrometric methodologies

Abstract

Underwater archaeological excavations at a shipwreck located in the port of Horta (Azores), uncovered a cargo of elephant ivory tusks, likely from a British merchant vessel that sank in the early 18th century. Since the ship’s route remains uncertain, determining the ivory’s provenance was essential for reconstructing its historical and commercial context. A multidisciplinary analytical approach combining X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and ancient DNA (aDNA) analysis was employed. FTIR spectra displayed a typical dentin profile, with Infrared Splitting Factor values (3.45–3.58) indicating moderate diagenetic alteration but overall good preservation. XRF results reflected both biogenic composition and post-depositional effects, with copper absence in two samples possibly linked to biological variation. Molecular analysis identified an African origin for the ivory, probably obtained during a stopover at an African port, supporting the initial archaeological hypothesis. This study also highlighted that EDTA removal after samples decalcification improves DNA extraction efficiency.