The 'invisible' product: developing markers for identifying dung in archaeological contexts

Dung is one of the most valuable resources in arid countries: traditional communities all over the world use it for heating, cooking, building and decorative purposes. It is commonly assumed that the same happened in the past, especially after the domestication of herbivores in the 11th millennium B.C. The presence and use of dung in archaeological contexts has been routinely studied through different techniques among which spherulites (calcium carbonates that form in animals guts) and small seeds assemblages' analyses. However all the proxies considered so far to trace dung can be unreliable, especially when used singularly. After a review of the traditional methods used to trace dung in archaeological contexts, this paper presents the results of an ethnographic study on 11 modern dung cakes collected in northern India that were analysed for chemical, spherulite and phytolith content. Our results show that the lack of spherulites cannot be taken as absence of dung input and that the combination of phytolith and chemical signatures can be a reliable proxy for the inference of dung presence in archaeological contexts. (C) 2011 Elsevier Ltd. All rights reserved.