Scientists collaborating across the globe have unlocked a new, astounding origin story for wine grapes, pushing back the domestication of Vitis vinifera, the grape species used for most winemaking, to more than 11,000 years ago. The findings suggest humans domesticated grapevines around the same time period they domesticated the first cereal plants.
"The grapevine was probably the first fruit crop domesticated by humans," said Wei Chen, an evolutionary biologist at Yunnan Agricultural University in China and a member of the study team.
Chen was speaking via videoconference, along with the study’s lead author, Yang Dong, at the American Association for the Advancement of Science conference in Washington, D.C., last week. They were presenting the results of the extensive study, undertaken by 89 researchers from over a dozen countries. The team sequenced 3,525 grapevine variety genomes, taking samples from private collections, research institutes, vineyards and fields in Europe, the Middle East, the Caucasus and Asia. They studied both Vitis vinifera and its progenitor, the wild Vitis sylvestris.
The dawn of farming
Until now, archaeological evidence suggested humans first domesticated grapes in the Caucasus Mountains—modern-day Georgia, Armenia and Azerbaijan—roughly 8,000 years ago, and that grapegrowing and winemaking spread from there around the world.
But the genetic record pushed the date back to 11,000 years ago, early in the current geological period: the Holocene. Previous timeline theories were determined by the archeological record, rather than evolutionary genetics. Now we can place winegrowing right around the advent of farming.
The second major news is that there wasn’t one sole origin event all those years ago, when humans began cultivating vines. "There are two domestication events that occurred at the same time," said Dong. These two locations for domestication were the south Caucasus and the western part of the Middle East—modern-day Lebanon, Israel, Syria and Jordan. The Vitis sylvestris grapevines that were domesticated in those locations, some 600 miles apart, were two genetically distinct populations of the wild plant, having been separated during the last glacial advance, allowing the researchers to distinguish between them.
While we don't know who these early grapegrowers were, or how the two farmer populations related to one another, archeologists do know that these people traveled, as evidence shows the movement of shells and obsidian between populations. Did ideas travel too?
"It's not like someone had the idea to domesticate grapes," evolutionary genetics professor Robin Allaby, of the University of Warwick in England, told Wine Spectator. "It's more the way they treated the landscape gave rise to grape domestication. Practices in that sense could have been exchanged, but it wouldn't have been quite, ‘Hey, we have this great new thing called grapes. Why don't you try this?’"
Allaby cautioned that domestication (the biological change in the grapevine) was a process that happened over thousands of years. "People have been interacting with plants for a long, long time," said Allaby. "We can see from the selection pressures that although more than 11,000 years ago is when domesticates appear and start to look different in the archeological record, the selection pressures involved actually have to theoretically go back quite a long time before then—we're talking thousands and thousands of years before."
It started with hunter-gatherers foraging for wild plants, then tending wild plants for fruit, followed by more intensive cultivation such as tillage and planting seeds, until they were finally farming domesticated plants.
Archaeobotanical evidence shows that grapes were already one of the annual plants exploited by people living in the Levant. At Ohalo II, a prehistoric settlement on the shores of the Sea of Galilee dating back 23,000 years ago, archeologists found the remains of wild cereals, such as emmer wheat and barley, nuts, grapes, figs and other fruit. The inhabitants had a grinding slab for making flour, but no evidence has been found that they were fermenting wine.
The spread of vineyards
The two origins of grapevine domestication have different legacies, which are present in today's wine culture. The south Caucasus was home to one of our earliest winemaking cultures, but the grapes grown there didn't spread very far. Grapegrowing spread from the Middle East into Western Europe. The genetic record shows that the grapevines moved eastward into Asia, toward Uzbekistan, Iran and China, then westward into modern-day Turkey, Croatia, Italy, North Africa, Spain and France.
The Middle East domestication established four major European cultivated grape clusters, said Allaby, which match the spread of neolithic culture into Europe. This was a period when, archaeologists believe, advanced toolmaking and farming spread from the Middle East to Europe. Questions remain whether the domesticated grapevines traveled via trade or with migrating people, but either way, it places winemaking deep in the history of human culture.
As vines spread, they changed, creating the great diversity of Vitis vinifera today. In Milan, Italian scientists supplied the DNA of wild Italian grapevines for the study. Genetic analysis revealed that when domesticated grapevines arrived from the Middle East, they mixed with local wild varieties, gaining new attributes. "Italy boasts a large number of wild grapevine populations that may have helped in shaping the modern varieties," said Gabriella De Lorenzis of the University of Milan’s department of Agriculture and Environmental Sciences.
Peter Nick, a German molecular biologist and head of molecular cell biology at Germany’s Karlsruhe Institute of Technology, spoke at the conference about how winemaking has shaped the landscape of southwestern Germany over the last 2,000 years. Now, through genomic testing, he said they discovered that German varieties have a surprising ancestry.
"This project, which investigates the genomic history of the grapevine, has helped us understand how German varieties arose and what gene flow has been shaping the evolution of the European wild grape,” Nick said. “We have learned, for instance, that genes coming from as far as Azerbaijan have entered the gene pool of our European wild grapes and of our varieties, which was a big surprise.”
"These genes have traveled along what is nowadays the Silk Road,” he added. “So one can now say the Silk Road has been a wine road."