Ancient DNA fragments inside Classical Greek amphoras reveal cargo of 2400-year-old shipwreck

The origins and spread of eastern Mediterranean civilizations 4000-2000 years ago constitute defining events in human development. Interregional connections across the sea played critical roles in building increasingly sophisticated economies and societies. Research of trade and exchange among these first centers has relied upon ancient societies' archaeological artifacts. The most ubiquitous artifacts recovered from shipwreck sites are ceramic transport jars, amphoras. However, for archaeologists and historians determining the original contents of these containers has been problematic, aided only occasionally by physical evidence (e.g. olive pits, resins) found inside excavated jars. Here, we investigate whether modern DNA analyses can reveal original contents of amphoras containing no visible physical remains. Using chloroplast DNA markers and PCR we analyzed the walls of two amphoras recovered from a 2400 year-old shipwreck off the Greek island of Chios. Our results show that short (≤100 bp) ancient DNA fragments can be extracted from scrapings taken from amphoras' interior walls. These DNA fragments identify the amphoras' original contents. Our analyses indicate that one of the amphoras most likely contained olive oil and oregano, even though no physical traces of remains are visible inside the jar. The second amphora might have contained mastic resin; resins of various types were preservatives commonly added to ancient wine. Our analyses are the first to demonstrate that ancient DNA fragments can be extracted from the walls of amphoras recovered from underwater shipwreck sites. This opens a new field of molecular archaeology analyses, and provides a powerful tool for obtaining information about the agricultural production, contact networks, and economies of the early civilizations.