Doctoral defence: Shidong Chen "Unravelling prehistoric plant exploitation in eastern Baltic: organic residue analysis of plant-based materials by multi-method approach"

On 12 September at 12:15 Shidong Chen will defend  her doctoral thesis "Unravelling prehistoric plant exploitation in eastern Baltic: organic residue analysis of plant-based materials by multi-method approach"  for obtaining the degree of Doctor of Philosophy (in Chemistry).

Supervisors:

Associate Professor in Analytical Chemistry and  Archaeology Ester Oras, University of Tartu

Professor of Analytical Chemistry Ivo Leito, University of Tartu

Opponent:

Shinya Shoda, Nara National Research Institute for Cultural Properties (Japan)

Summary

This PhD work is aimed at unravelling the plant exploitation in ancient eastern Baltic area with focus on two types of plant-derived materials: resinous materials and dietary plants. The main innovations are developing multi-methodological approaches and interpreting multi-proxy datasets with chemometric and statistical methods. For identifying the composition of resinous adhesives, ATR-FT-IR analysis was conducted in combination with a PCA-based DA classification model for further compositional and spatial/temporal classification. This method can help simplify IR spectra interpretation and reduce the need for GC-MS analysis. For identifying dietary plants, a multi-method approach was applied by plant micro fossil analysis and EA-IRMS combined with ORA. EA-IRMS can provide preliminary origins of samples with plant and/or animal bases. Plant micro fossil analysis and ORA in complementary can identify the species of plant remains. Correspondence analysis further compares and indicates the agreement of three methods and visualizes the correlations between the multi-proxy data The plant exploitation in prehistoric easter Baltic shows different patterns with dedicated multi-method case studies on several Stone Age, Bronze Age and Iron Age sites. In Stone Age, plant exploitation was more technological (adhesives and resinous compounds) than dietary-related. The plant consumption for dietary purposes became more abundant in the Bronze Age. The major changes happened with the Iron Age displaying more diverse plant-based diet with more inclusion of C3 cereals (e.g., wheat and barley), yet the spread and cultivation of C4 millet may not have emerged in this region.

Defence can be also followed in Teams.