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Taming Wheat Took Time
30 March 2006 (All day)
About 10,000 years ago in the Near East, the first roots of civilization were planted along with the first crops of wheat and barley. What happened next is a matter of debate. Some archaeologists believe that once people started domesticating crops, the practice spread rapidly across the Near East. Others argue for a much more gradual adoption. A new study lends strong credence to this latter view and suggests that early farmers were cultivating wild plants for a millennium or more before their harvests began to resemble today's domesticated crops.
Testing the slow-go hypothesis also took a fair bit of time. Archaeobotanist George Willcox of the National Center for Scientific Research in Lyon, France, and plant geneticist Ken-ichi Tanno of the Research Institute for Humanity and Nature in Kyoto, Japan, examined nearly 10,000 wheat spikelets--the flowering part of the wheat plant that is dispersed when it reproduces--that were unearthed during archaeological excavations. The researchers focused on four settlements of various ages in northern Syria and southeastern Turkey, where wheat was first domesticated.
They could only tell for sure whether the spikelets were domesticated or wild in 804 of the samples. Nevertheless, there was a clear trend: Over nearly 3000 years, the earlier sites had fewer domesticated spikelets, and the later sites had more. At a 10,500 year old site called Nevali Çori in Turkey, for example, only about 10% of the spikelets were clearly domestic, while 36% were domestic at 8500 year old el Kerkh in Syria and 64% at 7500 year old Kosak Shamali, also in Syria. When Willcox and Tanno added data on barley cultivation from two other sites near Damascus into the analysis, the gradualist trend held up, they report 31 March in Science. These results suggest that wild varieties were gradually replaced by domestic varieties, which arose by mutation and then were favored by the cultivation methods used, the authors say.
Archaeobotanist Gordon Hillman of the Institute of Archaeology at University College London, who was one of the first researchers to suggest a rapid transition from wild plant gathering to farming, says that he is "very impressed" with the paper. But Amy Bogaard, an archaeobotanist at the University of Nottingham in the United Kingdom, cautions against drawing firm conclusions because she says the dataset is limited. Nevertheless, Bogaard says, there's now more evidence that early farmers were growing wild plants before they were fully domesticated.