A crossdisciplinary project on opium poppy

The project aims to define a chrono-cultural framework for the early domestication of the Opium Poppy and its dispersal from Prehistory to the end of the Iron Age (6000-50 cal BC) in Europe and Southwest Asia. This project began in 2018 with the obtaining of funding from the Fyssen Foundation (coord. A. Salavert, MNHN, France) and the Agrichange project (coord. F. Antolin, univ. Basel, Switzerland) has laid the foundation for a long-term collaborative project. Two grants have been obtained in 2022, ANR JCJC Poppy (France) and FTC DOPE (Portugal) to pursue this research. The project is based on archaeological material, as well as on a sampling of modern and historical biodiversity conserved in seed banks and herbaria. It uses multidisciplinary analyses – archaeobotany, dating techniques, genomics, geometric morphometrics (GMM), spatial analyses.

A crucial need of an accurate chronological framework

Until recently, the hypotheses that have been proposed to assess the origin and early dispersal of the opium poppy are based on inaccurate chronological landmarks, i.e. the relative chronology (pottery, lithic industry) of the layer/structure where the opium poppy is coming from and/or absolute dates not directly performed on poppy. Furthermore, the very small size of seeds deemed impossible their direct dating (typically less than 10-30 microgram/seed). Now, the advent of a new generation of compact Accelerator Mass Spectrometry (AMS), together with optimized preparation protocols allows to significantly reduce the minimum amount of carbon required to date archaeological events . A recent pilot project, funded by the Fyssen foundation, has successfully tested the direct dating of short-lived botanical samples with a small amount of carbon (<100 µgC) (Salavert et al. 2020).

Searching for the wild progenitor

The lack of consensus on the phylogenic history of the opium poppy and its current natural distribution severely hinders the identification and location of its wild ancestor as well as the characterization of the plant domestication process. For about 50 years now, Papaver somniferum subsp. setigerum has been considered the wild ancestor of the cultivated opium poppy (Papaver somniferum subsp. somniferum). This assumption has been based on the easy interbreeding between the two subspecies and the fact that both are the only Papaver producing morphine, one of the most important alkaloids present in the plant. Furthermore, despite the fact that the wild opium poppy is not currently growing in the Near-East and Anatolia, a large diversity of species of Papaver is registered in the eastern Mediterranean Basin. Yet, a cultivated plant may not necessarily have originated where its wild form is recorded today, but possibly where the greatest number of species and varieties of the genus (here Papaver) are present. The current distribution of the wild opium poppy is thus not necessarily the same than in the Early and Middle Holocene. To unlock this interpretative barrier, new elements can be put forward to infer the history of its domestication and dispersal using molecular markers (single-nucleotide polymorphisms-SNPs) of modern landraces and wild accessions of Papaver spp. This method will allow the identification of its wild progenitor(s) as well as elucidate the early geographical movements of the plant. It has already been successfully applied to infer the history of important crop as emmer wheat (Oliveira et al. 2020).

Tracking domestication process in the archaeological records

ntil now, the distinction of the two opium poppy’s subspecies (i.e. somniferum and setigerum) cannot be performed on archaeological seeds. Research conducted some 40 years ago on modern seeds failed to differentiate both subspecies based on the size (height, width), general morphology and outer integument ornamentation . Thus, it is difficult to assess, with objective criteria, whether poppies are wild or domesticated on archaeological sites. New digital morphometric tools can provide an answer to this problematic. Geometric morphometric methods (GMM) allows the quantification of subtle size and shape differences within and between plant species. GMM is particularly useful when the diagnostic features of taxa overlap, and it is even powerful enough to distinguish regional varieties within the same species. Morphological criteria discriminating seeds of P. somniferum subspecies have been successfully identified in a recent pilot project (Jesus et al. 2021).



Citer ce billet
Aurélie Salavert (2023, 22 décembre). A crossdisciplinary project on opium poppy. Opium Poppy. Consulté le 25 juin 2024, à l’adresse https://doi.org/10.58079/vf3w

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