Editorial: Isotopes in Archaeological Science

Archaeometry, vol. 62, pp. 1–2

Abstract

Archaeology uses knowledge and techniques from many different academic disciplines, but one approach that has been particularly successful from the onset of archaeological science as a discipline is the assimilation and further development of isotopic analysis. Questions about diet and subsistence, migration, the natural environment, and the use, transport and exchange of raw materials and finished goods have all been investigated using mass spectrometry. Isotope ratio measurements in archaeology began with the investigation of inorganic materials, particularly metals and vitreous materials, but more recently archaeological chemistry has seen mostly biogeochemical tools applied to human and other organic remains. In inorganic materials analysis, just about every element of the periodic table has been used at some time to compare the typical composition of resource materials with that of archaeological artefacts. Depending on the nature of the materials analysed, multi-method provenance studies will often combine, for example, petrography and mineralogy with chemical techniques such as element and isotope ratio analysis. Elements and isotopic systems are chosen for their occurrence as major or trace element in the material under study, and the nature of the geological–mineralogical information they provide. Where the first applications of isotope ratio measurements were focused on lead, oxygen and then strontium, the last decade or so has seen the adaptation of new systems for archaeological research that use (but which are not exclusive to) neodymium, copper, tin, antimony and boron. In the analysis of organic materials, mostly human, animal and plant remains, and biomolecular components of residues in and on archaeological materials are examined. Best known are carbon and nitrogen isotopic analysis of bulk collagen in bone to estimate dietary patterns, to indicate the trophic level or to identify species. More recently, compound-specific isotopic compositions of a range of biochemical components, such as amino acids, are being looked at. Other applications include oxygen isotope ratios to indicate (bio-averaged) water intake, also acting as a proxy for temperature/precipitation and thus the climate of a region; and strontium isotopes, which are almost routinely used to track mobility of people and animals. Techniques are adapted quickly from the bio- and geosciences. New instrumentation continually makes new approaches possible, first for specialists and subsequently for archaeologists more widely. In this way, previously difficult-to-measure isotopic variations can be investigated, and eventually applied to archaeological research. The evolution from bulk analysis to high-resolution phase separation at very low detection limits has likewise allowed compound-specific analysis, while developments in (semi-)non-destructive sampling have made the investigation of rare and precious objects possible. Micro-sampling has also improved the spatial and thus (often) temporal resolution of the analysis of materials, making short-term studies possible within one individual or sample. This can then be balanced with longue durée studies, selecting different archaeological individuals, materials or contexts. Next to improving hardware, approaches to the nature of the data obtained and the treatment of (large) data sets have also experienced a paradigm shift. As boundaries are pushed for which part of the periodic table is used at which detection limit, it is being reassessed what old protocols and databases really can show. Many data sets could do with a thorough reinterpretation in terms of wider archaeological questions, for example, discussions about lead isotopes and their use in the reconstruction of pyrotechnology being a prime example. Unconventional data-processing and data-mining, and advanced statistical methods are often suggested for this purpose. However, the very nature of the material looked at is also sometimes put into question, as there may be doubt about whether the sample analysed can really answer the question asked. Both an optimistic view on what isotope ratio measurements can contribute to archaeology as well as some pessimism towards their practical and theoretical limitations can be observed in the papers presented in this special issue. What is certain is that isotopic analysis in archaeology can remain a key tool and an area of study for decades to come.

Authors 1

1. Patrick Degryse corresponding Aachen Faculty of Archaeology Leiden University Einsteinweg 2 Faculty of Archaeology, Leiden University

   Leiden University · KU Leuven

   Affiliation as printed

   Department of Earth and Environmental Sciences Katholieke Universiteit Leuven Celestijnenlaan 200 E, 3001 Leuven Belgium

   Faculty of Archaeology Leiden University Einsteinweg 2, 2333 CC Leiden The Netherlands

   Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Celestijnenlaan 200 E, 3001 Leuven, Belgium

   Faculty of Archaeology, Leiden University, Einsteinweg 2, 2333 CC Leiden, The Netherlands