AMS dating of insect chitin – A discussion of new dates, problems and potential

• The pre-treatment methodology shows satisfactory results on desiccated and carbonised material.
• Long term exposure in chemical solvents, primarily alcohols, may result in problematic dates.
• Insect diets do not have an effect on the quality of the dates.
• The taphonomy needs to be taken into account even when interpreting apparently secure dates.

Results from AMS dating applied to insect chitin from a variety of contexts and different preservation conditions and retrieval methods are presented. Secure contexts, which include other dated organic material from different geographic locations ranging from Egypt to Greenland and different chronological periods, from Lateglacial to Medieval, have been used. In addition, insect species with different dietary requirements have been selected for dating purposes in order to provide an understanding as to whether diet plays a role in the chitin dating results. Dates from each context/site are discussed separately in the context of their stratigraphy and/or archaeology. Our research concentrates on the results from pre-treatment methods which require small quantities of chitin as these could be applied in a variety of Quaternary and archaeological contexts. The dates from carbonised and desiccated remains where no chemicals had been involved in storage fell within the range of dates from other organics or the archaeology. Although some of the dates from waterlogged contexts were successful, problems were encountered and these have been linked with long term storage in various alcohols of uncertain provenance. Whilst short term immersion in paraffin (kerosene) and alcohols during processing probably has no impact, it is recommended that chitinous material for dating be stored in acidified distilled water. Our results demonstrate the potential of chitin as a dating medium and provide a basis for its wider application.