Investigating Isotopic Niche Space: Using rKIN for Stable Isotope Studies in Archaeology

Archaeological applications of stable isotope data have become increasingly prevalent, and the use of these data continues to expand rapidly. Researchers are starting to find that recovering data for multiple elements provides additional insight and quantitative data for answering questions about past human activities and behaviors. Many stable isotope studies in archaeology, however, rarely move beyond comparisons of descriptive statistics such as mean, median, and standard deviation. Over the last decade, ecologists have formalized the concept of isotopic niche space, and corresponding isotopic niche overlap, to incorporate data from two or more isotopic systems into a single analysis. Additionally, several methods for quantifying isotopic niche space and overlap are now available. Here, I describe the evolution of the isotopic niche space concept and demonstrate the usefulness of it for archaeological research through three case studies using the recently developed rKIN package that allows for a comparison of different methods of isotopic niche space and overlap estimations. Two case studies apply these new measures to previously published studies, while a third case study illustrates its applicability to exploring new hypotheses and research directions. The benefits and limitations of quantifying isotopic niche space and overlap are discussed, as well as suggestions for data reporting and transparency when using these methods. Isotopic niche space and overlap metrics will allow archaeologists to extract more nuanced information from stable isotope datasets in their drive to understand more fully the histories of the human conditions.