Grapevine in the Ancient Upper Euphrates: Horticultural Implications of a Bayesian Morphometric Study of Archaeological Seeds

Abstract

The origins of the main cultivar groups of Vitis vinifera, their relationships with wild grapevine populations, and the use of other Vitaceae are relevant issues for the improvement and conservation of Vitis diversity. Morphometric studies, domestication indices, multivariate analyses, and Bayesian hypothesis testing have been used. Eight different seed types have been identified in the 24 samples analyzed from materials from the Upper Euphrates sites of Tell Khâmis and Tell Qara Quzaq (Early Bronze Age to Hellenistic), ranging from highly domesticated to purely wild. We have been able to establish the predominance among the domesticated of Proles orientalis Negrul (three samples, Domestication Index = 1), the existence of and extinct Proles euphratica (six samples, Domestication Index = 0.67–0.83) and numerous intermediates and hybrids (eight samples). We have determined the continued presence throughout the period studied of wild grapevines related to Vitis sylvestris C.C.Gmelin and V. caucasica Vavilov (5 samples, with Domestication Indices = 0.17–0.5). The existence of Ampelopsis seeds was established for three samples. We determined that the oldest Vitaceae seed linked to human presence, in the Acheulense (780 myr), also belongs to Ampelopsis. Finally, “stenosperms” appear associated with Ampelopsis seeds (three samples), suggesting anomalies in seed formation due to intergeneric cross-pollination. Moreover, if isolated, they suggest the presence of “stenospermocarpic” Vitis vinifera raisins of the Sultanina type. Finally, we must reflect on the role that Ampelopsis species may have played and their possible cultivation and domestication almost 4000 years ago.

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“…Figs 3 and 6), for example at Tilbeshar (5400-3100 BC) and Grai Resh (5 th /4 th millennium BC) [61,62]. The find of underdeveloped grape seeds at Kurban Ho ¨yu ¨k dating to the end of the 4 th millennium BC also suggests grape cultivation [63] and fits with the results of morphometric analysis which identified domesticated grape by the latest in the 3 rd millennium BC in northern Mesopotamia [16].…”

“…Detecting possible early cultivation of grape outside its wild habitat using Zohary and Hopf's map [46] proves to be even more challenging. While this map suggests Tell Brak, where grape seeds and charcoal were found dating to 4000-3600 BC, lies outside the natural distribution range of wild grape vine, recent research indicates that this may not have been the case [16]. There are also other early finds of Vitis seeds from that region (cf.…”

“…We use the wild distributions for olive and grape as given in Zohary and Hopf [46]. Although recent research across several areas of our study region has demonstrated a wider distribution than Zohary and Hopf, especially for grape [16,[47][48][49], we apply the former to maintain regional consistency regarding the uneven distribution of recent studies, with the proviso that it likely represents an underestimation of the total distribution range.…”

“…However, there is a massive lack of data for the Northern Levant that may be crucial for our understanding of the processes. Recent morphological evidence from grape pips suggests that there was a hybrid of Asian and Caucasian domestic grape in northern Mesopotamia already by the 3rd millennium BC [16].…”

“…However, archaeological finds do not support the early dates inferred from genomics [14] and pollen dynamics of cultivated vine are difficult to identify [15]. Shape analysis of grape seeds from the Middle Euphrates region shows many grape varieties in the 3 rd millennium BC, amongst which a local variety of domestic grape, Proles, that was likely a hybrid of Asian and South Caucasian domestic vines [16].…”