Probing ancient shipwrecks with DNA
Jan 04,2008 00:00
Studying an ancient Greek shipwreck, scientists say, they’ve found they can decode ancient DNA to learn about the original contents of jars sunken for over 2,000 years.
It’s a feat “no one thought was even possible,” wrote Maria Hansson of Lund University in Sweden, one of the researchers, in an email. The discovery “opens up a whole new field of molecular archaeology,” she added, as scientists could use the technique to gain insights into ancient agriculture and trading networks.
Ancient Mediterranean civilizations, some of the world’s earliest, often used ceramic jars called amphorae as shipping containers. Invented by the Canaanites of the Near East in the 16th century B.C., amphorae took on varied styles in different regions and time periods, wrote Hansson and a colleague in a paper reporting their work.
Ancient amphorae, or storage jars, at the Chios shipwreck site. (Courtesy Chios 2005 Shipwreck Survey - WHOI, Hellenic Ministry of Culture: Ephorate of Underwater Antiquities, Hellenic Center for Marine Research)
Model of a 4th-century B.C. Greek merchant ship based on the Kyrenia, a wreck salvaged in 1967.
Piles of amphorae often remain as lone, mute witnesses to ancient shipwrecks where the boats themselves have been long since eaten away.
But researchers trying to learn the jars’ original contents usually come up dry, according to Hansson and colleague Brendan Foley of the Woods Hole Oceanographic Institution in Massachusetts. That’s because the amphorae only infrequently contain visible clues, such as olive pits.
Ancient DNA molecules, though degraded with time, could supply some of the needed evidence, wrote the pair, whose findings appear in the advance online edition of The Journal of Archaeological Science.
The researchers scraped ceramic from inside two amphorae from a 4th-century B.C. shipwreck found near the Greek island of Chios in 2004. The wreck, about 60 meters (200 feet) underwater, has drawn headlines before because—being to deep to explore by conventional diving—investigators have mapped it using robotic devices.
Adding another new technology to the project, Hansson and Foley analyzed small DNA fragments found trapped in the pottery.
They determined that one vessel probably contained olive oil flavored with oregano, a surprise because historians have believed that amphorae of that style from Chios usually carried wine, they wrote. Chios was known for “fine and distinctive vintages,” they noted, but the find suggests Chian agricultural exports might have been more diverse than generally assumed.
The other jar, they wrote, contained DNA of mastic—a shrub cultivated on Chios—or of pistachio, a related plant. Scholars have hypothesized that ancient Chians used mastic resin as a wine preservative and flavoring, Hansson and Foley wrote.
Some ancient foods, they added, are more likely than others to leave genetic calling cards behind. For instance, because the second jar was thought to have likely contained wine, they checked for grape DNA, but found none. It may have washed away because wine dissolves in water better than oil or resin, Hansson and Foley observed. But overall, they wrote, the findings “contribute definite evidence for Classical Greek commodity exchange and open new vistas for molecular archeological analyses.”
Courtesy of World-Science