Crop domestication: Baked beans

Sci. Rep. 5, 14370 (2015)

Fava or broad beans (Vicia faba) are a widely grown crop and the third most cultivated legume after soybean and pea. As well as being an excellent accompaniment to a fine Chianti they are particularly efficient nitrogen fixers. However, the origin of their domestication is unclear. By using carbon isotope analysis of archaeological samples Caracuta et al. have shown that fava was already a significant crop in the southern Levant over ten thousand years ago.

Fava bean grains have been found in abundance at three Neolithic sites in the Galilee region of northern Israel. However fava bean remains are rare or absent at other sites of a similar age in Israel, Syria and Turkey. These grains had been charred by fire complicating attempts at carbon dating. Therefore the authors first took modern fava beans and charred them at various temperatures to observe how the size of grains and their carbon isotope composition was affected.

With this modern data as calibration the researchers were able to use radiocarbon dating to determine that the earliest beans are 10,200 years old, while stable carbon isotope analysis showed that they had been grown at a time of relative water abundance. The success of this initial domestication probably relied on farmers' subsequent selection of seeds able to grow in the dryer conditions that later ensued.