The DNA sequences of both ancient and modern barley samples indicate that barley in Israel and Jordan has remained largely unchanged for the past 6,000 years. These results are reported in two studies published online this week in Nature Genetics, representing some of the most comprehensive genetic characterizations of this important cereal crop to date. The combined data clarify the domestication history of barely and its mechanisms of regional adaptation to different global environments.

Tzion Fahima, Johannes Krause, Ehud Weiss, Nils Stein and colleagues excavated 6,000-year-old barley grains from a difficult-to-access desert cave in Masada - an ancient fortress near the Dead Sea in Israel. The arid environment is favorable to biological preservation, so they were able to isolate genetic material and sequence the ancient DNA. In a separate study, Robbie Waugh and colleagues collected and sequenced the DNA of over 260 barley plants from around the world. These two unique data sets were analyzed and then compared to gain insights into the history of barley cultivation by early farmers.

The authors find that present-day barley from Israel and Jordan is the most closely related to the ancient grains, despite the influences of shifting farming practices and climate change over the past six millennia. This lends support to the idea that barley was originally domesticated in the Upper Jordan Valley before spreading across the globe.