Data Fusion Between Land and Sea: Multi-Isotope Fingerprints of Viking Animals and Modern Plants

Bioarchaeology aims to reconstruct, e.g., the diet or provenance of animals and humans in archaeological times. This can be done by investigating so-called multi-isotope fingerprints, resulting from the analysis of several different isotope systems in parallel. However, the multi-isotope fingerprint of samples from coastal regions can be influenced by the so-called sea spray effect, resulting in "too marine" isotope signatures in terrestrial herbivorous individuals, falling in-between less or un-affected herbivores and marine mammals when clustering the isotope data ("sea spray cluster"), what cannot be explained by the diet or habitat of these individuals. The recently proposed in-between instance (IBI) definition allows the detection of additional sea spray candidates, not grouped into the sea spray cluster, thus less affected by sea spray but still of interest to domain experts. The sea spray effect locally expected in archaeological individuals can also be investigated by isotope analysis in modern plants of the same region. The fusion of isotope data measured in archaeological bones and in modern plants allows us to investigate samples (un-)affected by sea spray, what is relevant for domain experts to understand the potential local range of isotope values at an archaeological site.