Washington, July 21 : A new study has shown that traces of ancient DNA can survive more than two millennia underwater, which can shed light on what was shipped in particular forms of amphorae in ships in ancient days.
According to a report in The Times, amphorae were the workaday containers of the ancient world, used to ship everything from aromatic wine to smelly fish sauce around the Mediterranean and beyond. housands have been found, in shipwrecks and in fragments at their destinations.
Over the years, certain assumptions have grown up as to what was shipped in particular forms of amphorae and from specific source areas, and the remains of pottery containers have stood proxy for their presumed contents' significance in ancient economies.
In most cases, no direct evidence of those contents could be obtained: long burial in the ground or on the seabed had, it was thought, washed away any evidence.
A new study now shows that traces of ancient DNA can survive more than two millennia underwater.
These can be multiplied using the polymerase chain reaction (PCR) established in forensic analysis to yield evidence of what the amphorae contained.
Writing in the Journal of Archaeological Science, Maria Hansson and Brendan Foley report some surprising results from research work of two complete 2,400-year-old amphorae that were found in a shipwreck off the Greek island of Chios, just off the Turkish coast.
According to the investigators, "The first is a 4th century BC style from Chios typically interpreted as a wine container, the second might be from the Eurasian mainland or Chios itself."
DNA was extracted from organic matter soaked into the vessel walls, cloned by PCR and their structures analysed using an automatic sequencer.
These were then matched with the genetic sequences of plants.
While the first amphora yielded evidence of olive and oregano, the second revealed a plant of the Pistacia genus.
But, neither vessel yielded the expected evidence of wine.
"Archaeologists and historians have assumed for several reasons that amphoras of this particular style from Chios usually contained wine," said Hansson and Foley.
The contents of the second amphora could have been either mastic or terebinth, both used for flavouring and preserving wine.
If the vessel had been used for wine, the absence of its DNA could have been due to degradation or its greater solubility.
It is also possible that the resinous material could have been used to seal the porous walls, keeping the wine from direct contact, according to the researchers.
"Our method enables isolation and identification of genetic fragments trapped for thousands of years and will provide fresh insights into the contents of ancient Mediterranean shipwreck cargoes and the functioning of protohistorical economic networks," the investigators concluded.