A Genetic History of Barley

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It’s what beer’s made of, and it comes from the Upper Jordan Valley.

By Nathan Collins


(Photo: Wikimedia Commons)

Barley is marvelous stuff. If nothing else, it’s what gave us beer and scotch whisky. It also makes for tasty bread, and it’s where we got the word “barn.” And, a new study confirms, barley was probably first domesticated in the last place many of us would expect: northern Israel’s Upper Jordan Valley.

From a biological standpoint, the Upper Jordan Valley actually makes a lot of sense. Though there’s evidence barley was domesticated in Tibet, a wild form of barley is common throughout the Fertile Crescent, the region comprising the Nile, Tigris, and Euphrates River valleys and the lands along the eastern Mediterranean Sea—home to both agriculture and civilization more generally. Indeed, it’s widely acknowledged that wheat, barley, and other crops were first domesticated somewhere in the Fertile Crescent.

Still, Martin Mascher and a slew of colleagues from Israel, Europe, and North America wanted to know if they could get more specific, and they had an interesting starting point from which to work: five well-preserved grains of barley recovered from Yoram Cave on the cliffs beneath the ancient Masada fortress. Radiocarbon dating put the age of those grains at roughly 6,000 years old.

Barley was probably first domesticated in the last place many of us would expect: northern Israel’s Upper Jordan Valley.

Having confirmed the barley grains’ ancient provenance, the team next compared their sample to wild and cultivated barley from Europe, Africa, and Asia. The ancient grains were most genetically similar to modern cultivated barley, or landraces, from Syria, Jordan, Israel, and Egypt. Among wild samples, the Masada grains were most similar to landraces from the Upper Jordan Valley. Finally, conducting the same genetic analysis between modern landraces and wild barleys suggested “the Upper Jordan Valley as a peak for genetic similarity with domesticated barley,” the team writes in Nature Genetics. Taken together, those results suggest northern Israel as perhaps the earliest site of barley farming.

In a separate Nature Genetics paper, Joanne Russell and many of the same co-authors from the Masada paper examine wild and domesticated barley’s genetic variation. Despite its origins in the Fertile Crescent, the team writes, it has undergone substantial genetic adaptation, allowing the grain to survive today everywhere “from the Arctic Circle to equatorial highlands to southerly latitudes.”

In particular, experiments conducted in Scotland, Germany, and Minnesota showed that genes associated with the plant’s height and the timing of its flowering contributed to barley’s adaptation to such a wide range of environments, although much remains to be learned, the authors note.