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By Claudia Moricca

Grapevine (Vitis vinifera) is one of the most important fruit crops of the past and present world, both economically and culturally. The wild and domesticated forms, respectively Vitis vinifera subsp. sylvestris and V. vinifera subsp. vinifera, differ by an array of traits, including the form of their seeds, which may be retrieved in archaeological assemblages. These are smaller, rounder and with a shorter stalk in the case of wild grapevine, and larger, more elongated, and less sharply sculptured in the cultivated varieties [1]. Due to these differences, morphometry – the statistical analysis of form and its (co)variation – has played a key role since the beginning of the 20th century for the study of grape pips retrieved from archaeological contexts, to distinguish wild and domesticated seeds [1][2]. Such approach, initially based on linear measurements, recently refined with geometric morphometrics and outline analysis [3], now allows to perform morphotype prediction within the domesticated compartment, thus approaching cultivar-level distinctions. While comparison of archaeological material with modern varieties is less problematic for desiccated and waterlogged samples, recent studies have shown that this is possible also for charred samples [4].

Although grape domestication and viticulture are believed to have originated in Georgia, recent SSR studies suggest the presence of at least two separate domestication events and several centers of diversity [5]. Nonetheless, there appears to be a clear link between Phoenicians and the spread of viticulture in the Western Mediterranean [6].

The present study – published in the Journal of Archaeological Science: Reports and performed in collaboration with Laurent Bouby, Vincent Bonhomme, Sarah Ivorra, Guillem Perez-Jorda, Lorenzo Nigro, Federica Spagnoli, Leonor Pena-Chocarro, Peter van Dommelen and Laura Sadori – aims to contribute to the investigation of the role of Phoenicians in the spread and trade of grapevine through morphometric analysis of grape pips. Waterlogged and charred samples were selected from three Western Mediterranean sites: Motya (Sicily), Nuraghe S’Urachi (Sardinia) and Huelva (Andalusia). While only Motya is a Phoenician foundation, all three were undoubtedly associated with Phoenician expansion and cultural interaction (Fig. 1).

Figure 1. The studied sites within the Mediterranean.

The comparison of archaeological pips preserved through different fossilization processes (waterlogging and charring) represented the key challenge. Although it is impossible to undo the charring conditions that created the archaeobotanical assemblage, experimental charring in reducing conditions of a set of selected cultivars from the “Vivaio Federico Paulsen” in Marsala (Sicily) was used to obtain seeds that may be compared to well-preserved archaeobotanical material. The use of two reference datasets of the same modern cultivars, one uncharred and one charred, has allowed to tackle the complications of differential preservation.

Modern (both pre- and post-charring) and archaeological grape pips were positioned on a blue background and photographed in dorsal and lateral position at a fixed magnification (Fig. 2). These images were processed to obtain black masks on a white surface. Outlines coordinates (x; y) were extracted and 360 points, equally spaced along the curvilinear abscissa were sampled. The outlines were normalized. Elliptic Fourier transform (EFT) approach was used to turn the shape into multivariate coefficients. The two views were treated separately, and their coefficients were later combined. A mean score was drawn up for each variety.

Figure 2. Experimentally charred “Perricone” pip in dorsal and lateral position.

The Momocs package [7] was used for morphometric analysis. All analyses were performed in the R environment, version 4.0.2 [8].

The PCA (Principal Component Analysis) approach was chosen to assess shape variability of the modern charred and uncharred pips and the archaeological seeds. These statistical analyses allowed an inter-site comparison, showing that samples from the three sites are clearly distinguishable based on their morphology (Fig. 3). It is also possible to identify different pip shapes within the site of Motya itself. This indicates the use of different varieties which may be due to different factors.

Figure 3. Archaeological seeds plotted against the (uncharred and charred) reference collection. PC1 (38.2%) describes elongation, while PC2 (21.0%) mostly captures the straightness/curviness of the pip outline in lateral view.

Statistical analyses of pip outlines show that archaeological material from these sites is morphologically comparable to that of modern varieties, suggesting that the archaeological finds may be described as “strongly domesticated”. Nonetheless, no apparent correspondence to modern cultivars was found. This is partly related to the limited size of the reference collection, to the centuries of history that have had an impact on grape diversity, and to taphonomic factors.

Our analysis represents a first step towards a better understanding of diachronic and synchronic relationship between vines grown in the ancient West Mediterranean.

More details at https://doi.org/10.1016/j.jasrep.2021.102991

Claudia Moricca (claudia.moricca@uniroma1.it) is an archaeobotanist, who recently obtained a PhD in Earth Sciences, curriculum Environment and Cultural Heritage, at Sapienza University of Rome (Italy) under the supervision of Prof. Laura Sadori and Prof. Lorenzo Nigro. Her thesis titled ‘Palaeonvironmental reconstruction of a Phoenician site: Archaeobotany at Motya (Sicily, Italy)’ concerned the archaeobotanical analysis of materials found in the archaeological site of Motya, a small island (ca. 40 ha) located in the Stagnone di Marsala, a coastal lagoon of western Sicily. She also studies plant remains from the excavation of Tell es-Sultan/Jericho, directed by Prof. Lorenzo Nigro. Furthermore, she has focused on the introduction of New World species to Europe, through the analysis of an Early Modern Age context in Rome (Italy).
During her academic career, she has had the opportunity to perform research in foreign institutions, including the University of Montpellier (France), the National and Kapodistrian University of Athens (Greece) and the Universidade de Evora (Portugal).

References

  1. Mangafa, M., Kotsakis, K. (1996). A new method for the identification of wild and cultivated charred grape seed, Journal of Archaeological Science, 23(3), 409–418.
  2. Stummer, A. (1911). Zur Urgeschichte der Rebe und des Weinbaues. Mitteilungen der Anthropologischen Gesellschaft in Wien, 61, 283-296. German.
  3. Terral, J.F, Tabard, E., Bouby, L. et al. (2010). Evolution and history of grapevine (Vitis vinifera) under domestication: new morphometric perspectives to understand seed domestication syndrome and reveal origins of ancient European cultivars, Annals of botany, 105(3), 443–455.
  4. Bouby, L., Bonhomme, V., Ivorra, S. et al. (2018). Back from burn out: are experimentally charred grapevine pips too distorted to be characterized using morphometrics?, Archaeological and Anthropological Sciences, 10(4), 943–954.
  5. Forni, G., 2012. The origin of “Old World” viticulture. Vitis, 51, 27–38.
  6. Pérez-Jordà, G., Peña-Chocarro, L., Fernández, M.G., Rodríguez, J.C.V. (2017). The beginnings of fruit tree cultivation in the Iberian Peninsula: plant remains from the city of Huelva (southern Spain). Vegetation History and Archaeobotany, 26(5), 527–538.
  7. Bonhomme, V., Picq, S., Gaucherel, C., Claude, J. (2014). Momocs: Outline Analysis Using R. Journal of Statistical Software, 56(13), 1–24.
  8. R Core Team (2020). R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna https://www.R-project.org.

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