14,000-year-old seeds indicate the Levantine origin of the lost progenitor of faba bean

Abstract

The understanding of crop domestication is dependent on tracking the original geographical distribution of wild relatives. The faba bean (Vicia faba L.) is economically important in many countries around the world; nevertheless, its origin has been debated because its ancestor could not be securely identified. Recent investigations in the site of el-Wad (Mount Carmel, Israel), provide the first and, so far, only remains of the lost ancestor of faba bean. X-ray CT scan analysis of the faba beans provides the first set of measurements of the biometry of this species before its domestication. The presence of wild specimens in Mount Carmel, 14,000 years ago, supports that the wild variety grew nearby in the Lower Galilee where the first domestication was documented for Neolithic farmers 10,200 years ago.

Figure 1. The context of study.

(a) Map of the Near East; (b) Location of the Natufian site of el-Wad and the Pre-Pottery Neolithic B sites of Ahihud, Yiftahel, and Nahal Zippori where the earliest domesticated faba beans were found. In grey the limit of the Lower Galilee. The images were created with QGIS Development Team, <2015>. QGIS Geographic Information System. Open Source Geospatial Foundation Project. http://www.qgis.org/.

Figure 2. Micro-CT views of Vicia faba L. from EWT.

(A) Lateral view of specimens O9d_B47 (Movie S1). The arrow points to the radicle which is only partially preserved; (B) dorsal view of specimen P7d_B123a (Movie S2). The arrow points to the bottom of the legume where the trace of the hilum was preserved; (C) top view of specimen P7d_B123b (Movie S3); (D) bottom view of P7d_B123a, the arrow points to the gray area in the middle where a trace of the hilum is preserved.

Figure 3. Calibrated date of faba bean from el-Wad Terrace.

Probability distribution of the calibrated radiocarbon range of the faba sample RTD 8021.

Figure 4. Plot of Principal Component Analysis (PCA) of the major Vicieae specimens.

The plot shows analogies and differences between the faba bean from el-Wad (), those from Ahihud, Nahal Zippori and Yiftahel (▲) and modern wild species native to Western Asia (○). The letters_a and_b are used to distinguish different seed and hilum outlines, within the same species. PCA axes 1 and 2 account for 65% of the cumulative variance. PCA axes represent respectively, the seed outline and the hilum relative length. For details, see Supplementary Table S3. Data for the modern species are from Zohary, Gunn and Perrino et al.. The plot was obtained using XLSTAT.