By Paul Arnold
The exact origin of bread wheat (Triticum aestivum) is still a mystery, but researchers believe they are edging closer to the source of one of the most important food staples worldwide. Using genetic studies and ancient plant remains, an international team of scientists has narrowed the location and timeline to the Neolithic period(around 8,000 years ago) in Georgia, in the South Caucasus. They present their findings in a paper published in the journal Proceedings of the National Academy of Sciences.
Bread wheat is the most widely grown type of wheat globally, accounting for around 95% of wheat production and consumption. Previous DNA studies of modern wheat plant genomes and wild grasses suggest that the South Caucasus and the Caspian Sea region were the likely places where the first mixing of domesticated wheat and wild goatgrass took place. This produced the hybrid that eventually became bread wheat. But that didn't settle matters, as no clearly identifiable physical evidence had been discovered.
Searching for ancient seeds
To find ancient plant remains, researchers sifted through soil and charred debris excavated from Gadachrili Gora and Shulaveris Gora in Georgia, two Stone Age villages.
Searching for burnt bread wheat seeds and distinguishing them from similar types, like durum wheat, is not easy because, when burnt, both appear similar. So researchers looked for the rachis, a tiny part of the stem that holds the grain to the ear of wheat and varies among species.
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