Seen by some as emblematic of the Mediterranean landscape and cuisine, the olive tree in fact has its domesticated roots in Kurdish regions, said a study Wednesday that seeks to settle an age-old debate.
Harvesting of wild olive trees called oleasters has been documented from the Near East (the area around ancient Palestine and Jordan) to Spain since the Neolithic or New Stone Age that started about 10,000 BC.
The tree then became domesticated, a process thought by some researchers to have started in the Near East about 6,000 years ago.
Other experts, though, have offered evidence for simultaneous domestication of different olive cultivars across the Mediterranean.
Now an international team of experts used genetic data, molecular dating, fossil records and climate modelling to determine that the iconic tree's roots lie in only one place—somewhat further north and east than many had thought.
"We conclude that the western Mediterranean was not a major primary centre of domestication of the olive tree," the team wrote in the journal Proceedings of the Royal Society B: Biological Sciences.
"The cradle of primary domestication of the olive tree is located in the northeastern Levant."
This refers to the modern-day Kurdish zone between Syria and Turkey, study co-author Guillaume Besnard of the French National Centre for Scientific Research (CNRS) told AFP.
From there, the domesticated olive probably spread through the eastern Mediterranean and Cyprus, westwards to Turkey, Greece, Italy and the rest of the Mediterranean "in parallel to the expansion of civilisations and human exchanges in this part of the world", said the report.
The domesticated olive tree, Olea europaea, is central to Greek, Roman and early Christian mythology, and the olive branch remains a symbol of peace today.
The ancient Greeks believed that Athena, goddess of war and wisdom, presented the Athenians with their first domesticated olive tree, from which all others sprouted.
"The importance of the cultivated olive tree in people's lives has turned this species into a symbol of ancient, sacred literature, and the origins of this crop are often subject to controversies," the paper said.
"According to our study, the maternal origin of the majority (about 90 percent) of cultivated olives today is clearly the Near East," or roughly the modern-day Middle East, added Besnard.
"I don't think anybody will dispute that any more."
For the study, the team sampled DNA data from 534 cultivated olive types and 1,263 oleasters from 108 locations, as well as 49 trees from a sub-Saharan subspecies.
The researchers also concluded that three main branches of wild olive split from a common ancestor at least 1.5 million years ago, said Besnard.
The olive tree has been called "the tree of life" for the sustenance it provides and its non-food uses, ranging from soap to oil for lighting and sculpture.
The olive today yields some 2.4 million tonnes of oil in Europe alone, with Spain the top producer.
It is farmed as far afield as southern Africa, Australia, Japan and China.
Explore further: Intracellular ABC transporters enable leaf beetle larvae to accumulate defensive precursors when feeding