As an archaeological chemist, I am interested in advancing scientific methods that reveal a direct and detailed picture of everyday life in the past, particularly in relation to food production and consumption practices and associated land use change.
My recent Humboldt Research Fellowship (2017–2019) at the University of Frankfurt used isotopic analysis of modern and archaeological crops to explore manuring practices during the first two millennia AD in Burkina Faso. I was involved in an ERC funded project at the University of Oxford (2013–2017), which assessed the role of changing agricultural practices in the emergence of urban centres in central Europe, the Aegean and southwest Asia. I obtained my PhD in Chemistry from the University of Bristol (2007–2012), applying nitrogen isotopic analysis of amino acids as a novel approach for the reconstruction of past diet and agricultural practices.
Resilience and breakpoints – exploring linkages between societal, agricultural and climatic changes in Iron Age Denmark (PI: Mads Dengsø Jessen)
Amino acid δ15N values of foliage of various plant taxa, grown at the experimental farm stations of North Wyke, UK and Bad Lauchstädt, Germany were determined by GC-C-IRMS. The difference between δ15N values of glutamate (Glx) and phenylalanine (Phe) were found to differ significantly between woody and herbaceous plants, with mean Δ15NGlx-Phe (i.e. δ15NPhe - δ15NGlx) values of -9.3 ± 1.6‰ and -5.8 ± 2.1‰, respectively. These differences in values are hypothesised to be due to the involvement of Phe in the phenylpropanoid pathway, by which lignin and other phenolic secondary metabolites are produced, leading to isotopic fractionation and enrichment of the remaining Phe pool available for protein biosynthesis. This results in the more negative Δ15NGlx-Phe values observed in woody plants relative to herbaceous plants, as the former are assumed to produce more lignin. To test this assumption, plant leaf tissue lignin concentrations were estimated by solid state 13C cross-polarisation, magic-angle-spinning (CPMAS) NMR spectroscopy for a subset of plants, which showed that tree foliage has a higher concentration of lignin (12.6 wt%) than herbaceous foliage (6.3 wt%). The correlation of lignin concentration with Δ15NGlx-Phe values demonstrates that the difference in these values with plant type is indeed due to differential production of lignin. The ability to estimate the lignin content of plants from amino acid δ15N values will, to give one example, allow refinement of estimates of herbivore diet in present and past ecosystems, enabling more accurate environmental niche modelling.