Archeologists from Canada are among a team of researchers who say they've unearthed the earliest evidence of winemaking in the world, dating the origin of the practice back hundreds of years earlier than previously believed.
The discovery, reported in a study being published this week in the journal Proceedings of the Natural Academy of Sciences, was made in the South Caucasus region in Georgia, a country on the border of eastern Europe and western Asia.
The excavations on the project were conducted by a team from the University of Toronto and the Georgian National Museum as part of a larger research project investigating the emergence of viniculture in the region. Researchers from the University of Pennsylvania were involved in studying materials recovered from the sites.
Previously, the earliest known chemical evidence of wine made from grapes was dated to 5,400 to 5,000 BC in Iran, but the archeologists say they can now trace the practice to about 6,000 BC in sites about 50 kilometres south of the Georgian capital of Tbilisi.
"What this shows is that (winemaking) was done in small scale in little villages and in the Neolithic period — and it's a period when we're experimenting with agriculture," said Stephen Batiuk, a senior research associate at the University of Toronto's Archaeology Centre, who co-authored the study.
The Neolithic period is characterized by activities that include the beginning of farming, domesticating animals and developing crafts such as pottery and weaving, and the early evidence of winemaking demonstrates further "human ingenuity" at the time, Batiuk said.
Fragments from ceramic jars recovered from the excavated sites were collected and anaylzed by scientists at the University of Pennsylvania to determine that the residue preserved inside came from grapes used to make wine.
"U of T's part is that we've been working with the Georgians on the excavations and what we did was, first of all, increased the area of excavation, changed the excavation strategies and brought in new methodologies," Batiuk explained, noting that the Canadian team joined the Georgian researchers about two years ago.
"It was a way of making sure that the samples that we would eventually get and send to (the University of Pennsylvania) for the analysis would be good, clean samples from good context that we could trace and date properly."
Archeologists found wide jars with narrow bases, which Batiuk said could mean that the wine was either partially buried or fully buried in the ground.
"This is important because this is the way traditional wine is made in Georgia," he said. "So this would suggest perhaps the technology had developed back then."
The absence of charred grape seeds, commonly found at ancient winemaking sites, remain a mystery for the archeologists though, the study says. It also means they are unable to determine the variety of grapes used in the wine.
"Seeds by themselves, they are organic, so they will disappear in the archeological record," Batiuk said. "The ones that are preserved for us, especially going all the way back to the Neolithic, these will be charred and, once they are turned into charcoal, they can survive much better.
"You could easily just say, 'well it's because they never actually exposed them to fire, so that's why we don't have any of them,' but that is kind of a tough argument to make because there is always accidental firing of these things," he added. "That is especially if you are pressing the grapes out afterward ... frequently enough people will toss them out in the fire and that will usually preserve some of the seeds."
Batiuk said the winemaking could have started where the grapes were grown, with the product then transported to villages for the fermenting process. He suspected the grapes could have grown in the wild in the nearby hillsides, an area he said his team plans to excavate next year.
He noted that the future excavation may yield new evidence of winemaking in the hillsides that could predate the current study.
"The hope then is as we move into the different time periods — later into the Neolithic and into the Chalcolithic — we can maybe start to see more of the experimentation and find the missing link between the sites in Georgia and the sites in Iran."
The methodology for identifying wine residues in ancient pottery was initially developed and tested on a vessel found in Iran 40 years ago by a team from the Royal Ontario Museum led by University of Toronto researcher T. Cuyler Young — one of Batiuk's former professors. It was also the oldest-known chemical evidence of wine until the recent discovery in Georgia.
"It's an amazing result after only two years of work," Batiuk said of the latest research. "The idea of actually bringing it full circle back to my original work with Cuyler makes it extra special."