A Massachusetts archeologist has borrowed crime-solving DNA methods from the State Police to reveal what the ancient Greeks carried in the pointy-bottomed clay pots they stacked in the hulls of ships that sailed the Mediterranean Sea.
Mostly, it wasn’t wine, said Brendan P. Foley of the Woods Hole Oceanographic Institution.
Foley’s tests of nine jugs, or amphorae, that date back more than 2,200 years found traces of DNA from olive oil on six and from grapes on five, in addition to DNA from herbs, nuts, ginger, and legumes. The amphorae were reused continually by the ancient civilizations, Foley said.
The results suggest the ancient Greeks, known for their love of wine, may have been serious about cooking.
“If we see wine, it’s with juniper, sage, or thyme mixed in with grape. That doesn’t sound like the kind of wine served at a symposium,’’ said Foley, who studies shipwreck remains to learn about ancient civilizations. The wine may instead have been a preservative for kitchen or medicinal herbs, he said.
As DNA tests become more sensitive, scientists are realizing they can use genetic fragments from ancient times to try to answer research questions. DNA extracted from the bones of Neanderthals, for example, has been analyzed, suggesting they interbred with humans.
“A quiet revolution is taking place in archeology with these kinds of studies, where you have sufficient organic preservation to allow the identification of DNA,’’ said Kevin Crisman, director of the Center for Maritime Archaeology and Conservation at Texas A&M University.
Scientists have sent Foley’s collaborator, molecular biologist Maria C. Hansson of Lund University in Sweden, more than 100 samples to identify with the ultrasensitive techniques used on the amphorae.
Patrick E. McGovern, an expert in ancient alcohol, conducts chemical analyses of the residues left in old terrestrial pottery, though not of the DNA, and has found alcohol present with thyme, rosemary, mint, and many other herbs, he said.
“These were ancient medicines,’’ said McGovern, scientific director of the Biomolecular Archaeology Laboratory for Cuisine, Fermented Beverages, and Health at the University of Pennsylvania Museum in Philadelphia. “They took herbs and put them into alcohol and either drank them or applied them to their skin.’’
McGovern has found a commercial application for his archeological techniques, consulting for Dogfish Head Craft Brewery in Delaware, which recreates facsimiles of ancient brews. Most recently, he helped the company develop Ta Henket, a beer fashioned after an ancient Egyptian drink with wheat, chamomile, Middle Eastern herbs, and dom-palm fruit, he said.
“I think we are breaking new ground. It’s a liquid time capsule that shows how humans and biology developed,’’ he said of Dogfish’s ancient beers.
Early on, Foley and Hansson took their investigation of amphorae contents to a certain point, then could go no further. They were stumped as to how to extract minuscule DNA fragments embedded in the clay of the ancient jars without harming the vessels. For help, the researchers turned to forensic heavy hitters: experts at the Massachusetts State Police crime laboratory.
Forensics scientist Joanne Sgueglia, previously with the state laboratory and now a validation manager for Life Technologies Corp. of Carlsbad, Calif., was able to advise Foley and Hansson.
“It’s the same method whether it is a very marginal amount of olive oil or in forensics, a tiny amount of occult blood that can’t be seen,’’ Sgueglia said. Also, the crime lab deals with eroded DNA on old evidence, just like the archeologists.
To extract the ancient DNA, Sgueglia suggested wiping the jars with chemically treated nylon squares textured like corduroy, which have tiny teeth that grab onto DNA.
“It very nicely captures the material. We can cover a greater surface area inside the jar this way,’’ Foley said.
Today’s DNA tests are so powerful that even if only 100 out of more than 1 million original base pairs - the molecular subunits that are the “letters’’ of the genetic code - are present in a sample of DNA, an analysis can be done, Sgueglia said.
None of the nine amphorae analyzed by Foley and Hansson, which were pulled up by fishermen from the bottom of the Mediterranean and stored for 20 years by Greek authorities, had more than 150 base pairs present, Foley said, but that was enough. He speculated that the water protected the amphorae from contaminants that could have interfered with the DNA tests.
Hansson matched the DNA from the jars to that of known plants and later created molecular tools to capture related DNA still left on the amphorae. The vessels tell a story, Foley said.
“If we think of a sailing voyage as a packet of information, we can eavesdrop on these ancient telephone calls,’’ he said.
“In the past, archeologists focused on the style of the jars,’’ Foley said. “They try to identify the source of the clay and there’s a whole lexicon to describe the shape of the jar [to discern where it might be from.] But there has been no analysis of their content because they are almost always empty.’’
Many scholars seem to believe that amphorae carried wine almost exclusively, Foley said. Of 27 published studies about amphorae, 95 percent refer only to wine being transported, he said. His latest research raises questions about that belief.
But Mark Lawall, a specialist in Greek amphorae at the University of Manitoba, disagreed that Foley’s research on amphorae significantly advances the study of them. Scholars already knew that ancient Greek amphorae contained more than wine, he said.
“The DNA studies have certainly added a new tool to the arsenal but they have not radically changed specialists’ understanding of these jars’ contents,’’ Lawall said in an e-mail.
Foley estimates 150,000 or so ancient shipwrecks rest on the floor of the Mediterranean, and he has started an ambitious project to survey all of them, he said. His goal: a complete picture of the ancient Mediterranean civilizations through the centuries, accomplished in 25 to 30 years.
“The wood of the ships has gone away but what you’re left with is an open book, the cargo is on display,’’ Foley said.
The MIT-trained Foley relies heavily on high-tech equipment, such as autonomous underwater vehicles that can be dispatched to depths of more than 300 feet and capture images, and a sonar system, from EdgeTech in Wareham, to map the contours of the sea floor.
“The goal is to survey huge areas of the sea floor and extract stuff as quickly as possible,’’ Foley said. “The bottom of the Med is a vast depository of early civilization. It’s just like time travel.’’