Species identification of archaeological dung remains: A critical review of potential methods

Abstract

Dung, macroscopically recognisable as such or not, can more commonly be found in archaeological contexts than is perhaps realised. Up to now, identification of dung to the species which produced it is usually either tenuous, or is not possible. However, species identification can be very informative and is necessary before any further studies can be conducted on the dung, for example on health and hygiene in the past and palaeoecology. This study presents a review of potential methods by which species identifications of archaeological dung can be undertaken. Criteria for identification can be divided into three broad categories: morphometric features of the dung; the content of dung and contextual evidence. Overall, the chances of a precise identification are high; however, a combination of different criteria and techniques will often be necessary to establish a secure identification. Moreover, preservation issues may exclude the application of some criteria while several criteria require more research and the expansion of reference collections of recent material. The overall aim is to move towards standardised methods for species identification of archaeological dung.     

Holocene archaeological evidence of extinct and very rare British Scarabaeoidea

Abstract

The analysis of British Holocene insect assemblages has discovered nine species of scarabaeoid dung beetles which are now extinct in Britain and two more that are extremely rare. Some of these species had been suspected as native by early 19th century entomologists but doubt had been cast on specimens in old collections of British Coleoptera. Eight are dung feeders which, although they would have initially been favoured by clearance for pasture and a possible warm climate episode in the middle Bronze Age, subsequently declined as a result of increasing cultivation and a slight cooling of the summer climate. The other three species probably became extinct due to human-induced habitat loss.     

Phytolith-rich layers from the Late Bronze and Iron Ages at Tel Dor (Israel): mode of formation and archaeological significance

The presence of many phytolith-rich layers in late Bronze and Iron Age deposits at Tel Dor, Israel, are indicative of specific locations where plants were concentrated. Detailed studies of six of these phytolith-rich layers and associated sediments from Tel Dor show that the phytoliths were derived mainly from wild and domestic grasses. The most common domestic grass was the cereal Triticum aestivum (bread wheat). Three of these layers have a microlaminated microstructure, associated dung spherulites and phosphate nodules; characteristics that all point to the phytolith-rich layers having formed from dung in animal enclosures. In two of the layers, the microlaminated structure is absent while dung spherulites and phosphate nodules are present, suggesting that these too originate from dung that was not deposited in an enclosure. The sixth layer is microlaminated but does not contain spherulites. We thus cannot suggest a parsimonious explanation of its observed properties. Concentrations of burnt phytoliths are present in three locations, implying that dung was either burnt in situ or the ashes from burnt dung were redeposited. The transformation of dung accumulations into phytolith-rich layers involves a loss of organic material and hence a significant reduction in sediment volume, which is clearly apparent in the stratigraphy of some of the locations examined. The volume reduction can be observed in the macrostratigraphy and has important implications with regard to macrostratigraphic interpretation. The presence of abundant phytolith-rich layers on the tell has significant implications for the concept of ‘urbanism’ during these periods.     

Subsistence practices in an arid environment: a geoarchaeological investigation in an Iron Age site,the Negev Highlands,Israel

The Negev Highlands (southern Israel) is an arid zone characterized by settlement oscillations. One settlement peak occurred in the early Iron Age IIA (late 10th and early 9th centuries BC). The most conspicuous structure in many sites of this period is an oval compound comprised of an internal courtyard surrounded by rooms. Two hypotheses for the function of these oval compounds are that they served as Israelite fortresses which guarded the southern border and routes of the Solomonic kingdom, or that they represent local agro-pastoral groups. In order to gather more information regarding the subsistence practices conducted in these oval compounds, we carried out a small-scale excavation at the site of Atar Haroa. We focused on sediment sampling and used several geoarchaeological, as well as isotopic, techniques in order to identify macroscopic and microscopic remains related to animal husbandry and crop agriculture. The remains identified from the archaeological sediments were compared with modern reference materials collected from abandoned Bedouin camps. The excavation included two half rooms and several test pits in the courtyard of the oval compound, featuring one Iron Age occupation level composed of gray sediments and relatively small amounts of pottery, bones and macro-botanical charred remains. Micromorphological, mineralogical, dung spherulite and isotopic analyses carried out on the gray occupational sediments from the rooms show that they originate from wood ash and dung, both used as fuel. Similar analyses of the gray sediments in the courtyard show that they originate only from degraded livestock dung. Phytolith analyses show that the gray anthropogenic sediments have similar concentrations of phytoliths as in control (yellowish) sediments and in the dung of winter free-grazing desert livestock and lichen-grazing black dwarf Bedouin goats. Phytoliths indicative of cereal crops are completely absent in the archaeological dung remains, indicating that cereal crops were not processed by the site inhabitants. Based on ethnographic and archaeological parallels, and on the presence of grinding stones and absence of sickle blades in the excavated rooms, we infer that the inhabitants at the oval compound at Atar Haroa subsisted on livestock herding and bought or exchanged cereal grains. Our results support the hypothesis that the inhabitants at the oval compound at Atar Haroa were desert-adapted pastoralists, rather than garrisoned soldiers.     

The relative abundance of Onthophagus species in British assemblages of dung beetles as evidence for Holocene climate change

Abstract

The ratio between scarabaeid beetles of the genera Aphodius and Onthophagus in European dung faunas is influenced by summer climate, such that individuals of Aphodius species predominate in Northern Europe but are largely replaced by Onthophagus species in the Mediterranean region. Detailed study of insect assemblages from Neolithic to Saxon date showed a changing ratio between the genera with time. For the Neolithic and most of the Bronze Age, individuals of Onthophagus contributed around 16% of the sum of Aphodius and Onthophagus, but during the Iron Age the proportion of Onthophagus fell to around 3% and remained low. This decline of Onthophagus was probably the result of a slight cooling of mean summer temperature and agricultural intensification. However, the proportion of Onthophagus peaked at over 60% during the middle Bronze Age around 1450 BC. This is argued as reflecting a brief warm episode with mean July temperatures for Central Southern England at least 2°C warmer than at present.     

Fuel, Fire and Heat: an experimental approach to highlight the potential of studying ash and char remains from archaeological contexts

As in traditional societies today ancient societies probably selected different fuels to meet specific heat requirements. Char and ash, the end products of fire, are often found in abundance in archaeological contexts. These end products can provide information regarding (i) the original fuel resource and type, (ii) the characteristics of the fire and (iii) combined with other archaeological evidence shed further light on possible socio-economic activity(-ies) associated with that fire. The three main fuel resources would have been (i) modern vegetation, (ii) fossil fuel and (iii) animal by-products. Local availability and abundance would have influenced the choice made.In this study an experimental approach was adopted to try and distinguish between the three different fuel resources that are known to have been used by ancient societies (and continue to be used by traditional societies today) from their char and ash remains to help determine original fuel-type and understand the relative heating properties. For this end one fuel-type from each fuel resource listed above, namely wood, peat and cow dung, was chosen.     

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.     

Holocene hyrax dung deposits in the afroalpine belt of the Bale Mountains (Ethiopia) and their palaeoclimatic implication

Abstract

The results of pollen analysis and radiocarbon dating are presented for two hyrax dung deposits from rock shelters found in the Afroalpine zone of the Bale Mountains (South-Central Ethiopia). Deposits accumulated from about 15,000 to 1500 (cal) years BP and from 7000 (cal) years BP till nowadays, respectively. Pollen spectra of the initial stages of deposit development (up to 15,000 (cal) years BP) correlate with unfavourable conditions in the Late Glacial Maximum. The African Humid Period (AHP) (15,000–5000 (cal) years BP) is registered in this palaeoecological record as well as the Younger Dryas event (about 12,500 (cal) years BP). Upward shift of Afromontane forest belt and expansion of ericoid communities at high altitudes were characteristic of the Pleistocene/Holocene transition (about 10,000 (cal) years BP). The AHP which continues around 10,000 (cal) years BP after Younger Dryas, was interrupted by a dry episode around 8200 (cal) years BP. Principal aridisation trend during the last 5000 years was observed. Presumably the first traces of human activities in this area can be shown for up about 2500 (cal) years BP.     

What goes in does not always come out: The impact of the ruminant digestive system of sheep on plant material,and its importance for the interpretation of dung-derived archaeobotanical assemblages

Abstract

On archaeological sites where livestock dung was a major fuel source, plant material that survives digestion intact may well be preserved in the remnants of dung-fuelled fires. Preserved plant remains which were derived from dung relate to the diet of animals, and thus provide a way of investigating the agro-pastoral economies of the past. In order to improve our understanding of the taphonomic processes to which plant material is exposed to during digestion, we applied archaeobotanical methods to the analysis of dung from sheep fed a known diet of cereal and wild plant material. Two clear patterns emerge from these investigations. First, cereal material (grain or chaff) survives digestion poorly and was rarely found in the dung analysed. Second, large proportions of seeds of various wild species survive digestion in an identifiable form, probably due to their small size and/or protective coating. These findings are crucial for reliable interpretation of dung-derived plant material in archaeological settings.