Contribution of GMM to track domesticaiton process

A paper recently published in PlosOne showed the potential of GMM to address questions about poppy domestication, based on waterlogged archaeological poppy seeds. These seeds are the most direct and common evidence found on archaeological sites, unlike the capsules, which are rarely recovered. Seeds are therefore probably the only archaeological tool that can provide substantial, diachronic and geographically broad information on the domestication/cultivation process.

Scientific framework

This paper is part of the Ph-D thesis of A.C. Jesus, which was defended at IPAS (University of Basel, Switzerland), in the frame of the Agrichange project1, in collaboration with ISEM (Montpellier, France). A previously published paper had already highlighted the contribution of GMM and statistical tools in distinguishing species of poppy, mainly on the basis of current seeds. This paper applies the same methodology and uses the reference samples from the previous publication to classify uncharred (waterlogged) archaeological seeds.

Dataset and results

Several Neolithic and one Bronze age sites (5300 to 1070 cal. BC) with uncharred poppy seeds were analysed. Three specific questions were asked: (1) Is there a relationship between changes in grain size and shape and chronology? (2) Is there a particular relationship between archaeological seeds from Mediterranean and Alps sites? (3) Is the seed morphotype closer to the domestic or wild opium poppy?

Several descriptive criteria were taken into account, following the method published in the previous publication mentioned above: the size of the grains (length, width), their shape and the number of cells on the seed outer envelope.

From Jesus et al. 2023, fig 3. Unrooted tree obtained with hierarchical clustering on the euclidean distance matrix between Fourier coefficients, length, width and number of cells per site. The colours of the lines represent the period colours seen in the previous figures. Photos by Raül Soteras.

The seeds are smaller on the Mediterranean sites than those in the Alps and a continuous change is observed in the width and shape of seeds during the Neolithic period. But this change is most noticeable in the Late Bronze Age (LBA). In the same way, the proportion of seeds with domestic morphotype is higher in non-Mediterranean regions , especially in the LBA. Some differences are also noticed at the regional scale as the width and number of cells are higher north than south of the Alps, whichcan be explained by environmental or varietal differences, or the degree of opium poppy domestication.

The GMM of waterlogged archaeological seeds would therefore reveal the beginnings of domestication or cultivation process of the plant as early as the Neolithic period, but especially at LBA, and outside of the Mediterranean region.

Perspectives

These results are very promising. They demonstrate the value of taking all four descriptive factors into account when studying the domestication process of opium poppy. As the authors point out, this method needs to be applied to a wider range of sites, especially from Neolithic Central Europe in order to tackle this complex issue. A development on carbonised poppy seeds is envisaged as this is a very common preservation state on well-drained sites in Temperate Europe and the Mediterranean.

This work is continuing as part of the ANR poppy project. Not only many more reference samples will be studied, but they will be integrated in ongoing genetic research and all of these analyses together with the archaeological database will enable us to propose a model regarding domestication and varietal diversification of the opium poppy in the coming years.

Reference

Jesus, Ana, Vincent Bonhomme, Allowen Evin, Raül Soteras, Stefanie Jacomet, Laurent Bouby, et Ferran Antolín. 2023. « Morphometrics of Waterlogged Archaeological Seeds Give New Insights into the Domestication and Spread of Papaver Somniferum L. in Western Europe ». PLOS ONE 18(5):e0286190. doi: 10.1371/journal.pone.0286190.



Citer ce billet
Aurélie Salavert (2023, 11 juin). Contribution of GMM to track domesticaiton process. Opium Poppy. Consulté le 25 juin 2024, à l’adresse https://doi.org/10.58079/sjr3

  1. note: Project SNF Professorship “ Small seeds for large purposes: an integrated approach to agricultural change and climate during the Neolithic in Western Europe” (2018-2021, PI: F. Antolin, University of Basel []
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