Ancient shipwrecks and archaeological science: characterising cargo items through stable isotope, organic residue, and DNA analysis
Keywords: shipwreck, DNA, isotopes, organic residue analysis, archaeological science, Uluburun, Cape Gelidonya, Kyrenia, Mazotos, Babuljas

Finding a way to accurately characterise the contents of cargoes from ancient Mediterranean shipwrecks would provide invaluable insight into economic, agricultural, and social transformations in antiquity. The three forms in which ancient shipwreck cargo items survive in the archaeological record, as macro-remains, visible residues, and molecules invisible to the naked eye, are analysed here in order to better understand what these ships were transporting, and why.
Despite the abundance of preserved organic material found on shipwrecks, the use of stable isotope analysis on waterlogged archaeological plant material remains largely unexplored. Here we present the results from a small, preliminary isotopic study of olive stones recovered from the 4th century B.C.E. Mazotos shipwreck, Cyprus. Analyses of the stable isotopes of carbon and nitrogen are conducted on 20 ancient, waterlogged olive stones from the Mazotos wreck and 10 modern olive stones from Chios, Greece. The extent of lipid retention, and preservation of original isotopic composition is explored. The possibility of determining the geographic origin of the Mazotos olive stones by isotope analysis is assessed.
The majority of amphorae recovered from ancient shipwrecks appear empty on first inspection, or with barely visible residues adhering to the vessel walls. Ceramic vessels thought to have contained either wine or olive oil recovered from multiple Mediterranean shipwrecks and one terrestrial site are analysed through GC-MS to investigate past vessel contents. Assumptions regarding vessel shape as a determining factor in past use are discussed. Environmental samples from shipwreck sites are analysed and compared with results from GC-MS. Results show a prevalence of conifer products in vessels thought to have contained wine. Environmental samples of seafloor sediment and soil from both the shipwrecks and the terrestrial site contain syringic acid, calling into question the utility of relying on syringic acid as a wine biomarker. Molecules from unexpected or unusual contents were detected in several vessels.
The third method by which this research attempts to characterise ancient shipwreck cargo items is through ancient DNA analysis. There is tremendous potential for DNA studies to resolve long-standing questions in both terrestrial and underwater archaeology. Great optimism for the recovery of ancient DNA (aDNA) from maritime sites has spurred a series of studies claiming to have successfully extracted aDNA from a variety of artefacts recovered from underwater sites including plant remains, human skeletons, and shipwreck amphorae. However, these studies have not adequately addressed the source of the DNA recovered: does it derive from taxa present in the underwater deposition environment or the artefact itself? My research attempts to address this ambiguity by examining the efficacy of extracting aDNA from the ceramic matrix of vessels recovered from six ancient Mediterranean shipwrecks and establishing what DNA can be found in the water column and seafloor sediments that surround these sites. The methods used in this research are designed to enhance current methods, which do not characterise the deposition environment, and utilises shotgun metagenomics to characterise the DNA found on ancient shipwreck sites.