In a first, an international team of researchers has successfully sequenced the genome of 6,000-year-old barley grains retrieved from Yoram Cave in Israel's Judean Desert which was used only for a short time by pre-historic humans probably as an ephemeral refuge.
The team found that genetically, the pre-historic barley was very similar to present day barley grown in the Southern Levant, supporting the existing hypothesis of barley domestication having occurred in the Upper Jordan Valley six millennia ago.
"These archaeological remains provided a unique opportunity for us to finally sequence a Chalcolithic plant genome. The genetic material has been well preserved for several millennia due to the extreme dryness of the region," said Ehud Weiss from Bar-Ilan University in Israel.
In order to determine the age of the ancient seeds, the researchers split the grains and subjected half of them to radiocarbon dating while the other half was used to extract the ancient DNA.
"For us, ancient DNA works like a time capsule that allows us to travel back in history and look into the domestication of crop plants at distinct time points in the past," said Johannes Krause from the Max Planck Institute for the Science of Human History in Jena, Germany.
The genome of Chalcolithic barley grains is the oldest plant genome to have been reconstructed to date.
Wheat and barley were already grown 10,000 years ago in the Fertile Crescent, a sickle-shaped region stretching from present day Iraq and Iran through Turkey and Syria into Lebanon, Jordan and Israel.
Till date, the wild forms of these two crops persist in the region. It was from there that grain farming originated and later spread to Europe, Asia and North Africa.
The results of the analysis were published in the journal Nature Genetics.