The application of histomorphometry and Fourier Transform Infrared Spectroscopy to the analysis of early Anglo-Saxon burned bone

Macroscopic examination, histomorphometry and Fourier Transform Infrared Spectroscopy (FTIR) are applied to the analysis of burned bones from the early Anglo-Saxon cemetery at Elsham in Lincolnshire, UK. These methods were undertaken to gain a greater understanding of pyre conditions from an archaeological context and the effects of burning on bone microstructure. Sixteen samples were employed for thin-section analysis while eight samples were used with FTIR. The results suggest that these methods correspond well with macroscopic examination, though anomalies did occur. The techniques employed in this paper have demonstrated that the temperatures reached on the funerary pyres at Elsham ranged from 600 °C to over 900 °C under oxidizing conditions.     

The application of a new method of Fourier Transform Infrared Spectroscopy to the analysis of burned bone

A new method of Fourier Transform Infrared Spectroscopy (FTIR) is applied to the analysis of burned bones. FTIR analyses were undertaken to examine changes in Crystallinity Index (CI), Ca/P and C/C ratios in bone experimentally burned to known, but varying, temperatures and durations. Three sample groups were used to assess the new FTIR method. Blind tests were performed to assess the use of the CI for predicting burning conditions. The results suggested that the new method of FTIR was preferable to the traditional approach, but that CI is affected by factors other than temperature of burning, including the method of FTIR used, and that predictions of burning conditions in archaeological material may not extend beyond that of ‘high’ or ‘low’ intensity of burning.     

Infrared and Isotopic Evidence for Diagenesis of Bone Apatite at Dos Pilas, Guatemala: Palaeodietary Implications

The use of stable carbon isotopic analysis of bone apatite to reconstruct prehistoric diets is hindered by the possibility of diagenetic alteration of carbonate during burial. We examine apatite preservation in Classic Period Maya skeletal remains from Dos Pilas, Guatemala, using Fourier transform infrared spectroscopy (FTIR). We use weight % CO₂evolved from apatite, FTIR carbonate/phosphate absorbance ratios, phosphate peak splitting crystallinity indices, fluoride peaks, and stable oxygen isotopic ratios to identify diagenetic change in apatite chemistry. Isotopically light carbon taken up from burial soil is adequately removed from most Dos Pilas bone by treatment with dilute acetic acid, but more severe alteration cannot be reversed by standard preparation methods. Infrared criteria identify recrystallized apatite in a subset of Dos Pilas burials, that is accompanied by isotopic exchange, and that no longer preserves biogenic δ¹³C. These results illustrate that comparatively recent bone may be diagenetically altered and demonstrate a need for systematic evaluation of mineral integrity in all archaeological bone prior to interpreting paleodiets with apatite δ¹³C.     

Examining histology to identify burned bone

Early research suggests that examination of the microscopic internal structure is a valid method for distinguishing burned from unburned bone in the archaeological record. This study compares burned and unburned modern bones with archaeological bones from Sibudu Cave (ca. 60,000 years ago) and Cave of Hearths (over 200,000 years ago) to more fully describe the heat-induced histological changes to bone. We also explore the effects of diagenesis on those changes to determine if histological evidence of burning preserves through fossilisation and diagenetic processes and can be successfully used to identify ancient burning. Application of this technique can help in addressing various issues, including the origins of controlled use of fire and understanding animal butchery and disposal.     

Implications of heat-induced changes in bone on the interpretation of funerary behaviour and practice

Bones submitted to heat experience structural and chromatic modifications. In particular, heat-induced bone warping and thumbnail fractures have been linked to the burning of fleshed and green bones – where the soft tissues have been removed from the bones soon after death – in contrast to dry bones. Those have been suggested as indicators of the state of the individual before being burned thus allowing inferences about the funerary behaviour of archaeological populations. A large sample of 61 skeletons submitted to cremation has been examined for the presence of both of these heat-induced features. Although uncommon, bone warping and thumbnail fractures were present in some of the skeletons demonstrating that its presence is not restricted to the burning of non-dried bones as generally believed. Rather than being an indicator of the presence of bones with soft tissues, bone warping seems to be more of an indicator of the preservation of collagen–apatite links which can be maintained on dry bones with low collagen deterioration. In addition, our results also do not confirm thumbnail fractures as an exclusive sign of the burning of bones with soft tissues. As a result, these heat-induced changes should be used with caution when trying to infer about the pre-burning state of an individual.     

Silver lining: evidence for Inka silver refining in northern Chile

Prehistoric silver purification using lead cupellation has been documented in multiple places throughout the Andes, but direct evidence of the Inka use of this technology has remained elusive. In this study, we use X-ray fluorescence, scanning electron microscopy, and electron-microprobe analysis to document direct evidence of Inka period (AD 1400–1532) silver purification using lead cupellation in the Tarapacá Valley of northern Chile. Local metalworkers used wind-driven huayra furnaces to produce pure lead metal, sustaining temperatures of ca. 900–1100 °C to smelt lead-bearing ores that may have included galena. The lead metal was then used in open-vessel cupellation of silver-bearing ores, some of which may have been cupriferous and derived from the nearby Inka mines at Huantajaya. Phase analyses of the slagged interiors of bowl-shaped ceramic vessels used for cupellation indicate that the metalworkers maintained the oxidizing environment and temperatures between 800 and 1100 °C requisite for cupellation. We argue that the Inka introduced this technique to Tarapacá metalworkers. The absence of finished silver artifacts in local valley contexts suggests that the refined silver was removed from the valley for use elsewhere in the empire.     

In search of the optimum Raman/IR signatures of potential ingredients used in San/Bushman rock art paint

Vibrational spectroscopy (Raman and FTIR) has played an important role in identifying pigments, substrata and deterioration products in rock art studies worldwide: in the laboratory and on-site. However, the detection of organic binders and carrying agents has so far been scarce and the quality of many spectra recorded on-site inadequate. In this study, possible pigments (charcoal, ochre, raptor faeces, thermally treated ostrich egg shell, etc.), binders (fat, egg, blood) and carrying agents (saliva, gall, egg, water) were selected based on artistic considerations and analysed with FTIR and Raman (514.6 and 785 nm excitation, both available in mobile instruments) spectroscopy in order to determine usable marker bands for each ingredient. The resultant marker bands were then used to analyse five ten year old San replica paints. It was found that FTIR spectroscopy is very efficient to identify organic compounds as there is no fluorescence but the broadness of the bands inhibits the exact assignment of many ingredients. A high fluorescence background experienced for many natural products prevented the recording of Raman spectra for all ingredients, in many instances though the sharp peaks usually associated with Raman spectra make identification easier than with FTIR spectroscopy. Most of the ingredients in the paints could be identified, but it is clear that better results are obtained when more that one technique is used.     

An investigation of cortical bone loss and fracture patterns in the neolithic community of Çatalhöyük,Turkey using metacarpal radiogrammetry

Bioarchaeologists have conducted numerous studies on human skeletal remains using metacarpal cortical bone radiogrammetry. This method allows cortical thickness of the second metacarpal to be quantified. As a sensitive index of bone health metacarpal cortical thickness is evaluated in the context of functional adaptations, growth, ageing and bone loss in osteoporosis, as well as used as a reliable indicator of fracture risk. The focus of this study is an examination of the widely used calculation that expresses second metacarpal cortical bone values, followed by an examination of age and sex-related patterns of cortical bone loss and skeletal fragility fracture in a Neolithic archaeological skeletal sample from Çatalhöyük, Turkey. Using metacarpal radiogrammetry, 49 adult metacarpals (f = 27 m = 22) were examined. Data were collected for size variables, length (L) and total bone width (TW) as well as quantity variables, medullary width (MW) and cortical thickness (CT). These parameters were then used to calculate the widely used cortical index (CI) and two new indices expressing medullary width and cortical bone thickness in relation to length (medullary width index, MWI and cortical thickness index, CTI). The ratios were then used to explore age- and sex-related cortical bone loss and fragility fracture patterns amongst the inhabitants of Çatalhöyük. Çatalhöyük males and females demonstrate an inverse relationship where CTI decreases as age and MWI increase. Analyses indicate statistically significant age-related change in MWI amongst the oldest females. Despite age-related loss of bone, no typical fragility fractures are observed. We discuss the role of ageing and lifestyle factors at Çatalhöyük that may have been beneficial to skeletal health and a reduction in the risk of fragility fracture.     

Sorting the butchered from the boiled

Is it possible to identify cooked, rather than burnt, bone? Mild heating (≤100 °C,1 h) – typical of cooking – does not lead to detectable changes in any biochemical parameter of bone yet measured. If it is only possible to detect charred bone, how is it possible to detect cooking in the archaeological record? In a previous paper (Koon et al., 2003, J. Arch. Sci.), we used a Transmission Electron Microscopy (TEM) based approach to investigate changes in the organization of the bone protein, collagen, as it is heated, using bone from heating experiments and short term burials. The work revealed that mineralized collagen, despite requiring aggressive treatment to gelatinise the protein (e.g. 90 °C, 240+ h), readily accumulates minor damage. We believe that the presence of mineral matrix stabilises the collagen enabling the damage to accumulate, but preventing it from causing immediate gelatinisation. Once the mineral is removed, the damage can be observed using appropriate visualization methods.     

Decorated prehistoric pottery from Castello di Annone (Piedmont,Italy): archaeometric study and pilot comparison with coeval analogous finds

Prehistoric pottery decorated with incisions or impressions filled with white and seldom coloured inlays is well documented in the archaeological literature, but the related in-depth archaeometric studies are sporadic. 43 decorated ceramic shards, dating from the Neolithic to the Bronze Age, and an Iron Age fibula from the archaeological site of Castello di Annone (Piedmont, North-Western Italy) were analysed with FTIR, Raman and XRPD for characterization of the ornamental pigments forming these inlays. Few white components were used as fillers, namely talc and bone ash (hydroxyapatite – Bone White), often as a mixture and seldom accompanied by other pigments (i.e. kaolinite and presumably secondary calcite). Comparison with freshly-heated biogenic hydroxyapatite proved that ancient Bone White pigment was calcined at about 900 °C. Such a process was kept separate from pottery firing as these white mixtures show absence of talc degradation by-products and sporadic presence of kaolinite, implying these ceramics were decorated only after firing in furnace. Actual presence of fluorapatite in bone ash could allow dating with the Fluorine Method, but lack of fluorine detection with SEM-EDS causes such an attempt to be impracticable so far. A pilot comparative study with a restricted but representative group (11) of coeval finds from other sites of Piedmont suggests that while recurrence of talc prevails in Castello di Annone from the Neolithic throughout the Bronze age, massive use of bone ash (Bone White) becomes widespread in the close Iron Age settlements, possibly consequent to a more efficient handling of its production technology.     

FTIR and statistical studies on amber artefacts from three Romanian archaeological sites

In the present study Fourier transform infrared spectroscopy in the reflectance mode (FTIR-reflectance) – was performed on well preserved archaeological amber, originating from three Romanian archaeological sites of Roman and Byzantine cultures, which did not allow sampling material. Resulting spectra were subjected to multivariate data analysis (MDA) using Principal Components Analysis (PCA). In the light of the FTIR-reflectance bands of archaeological samples from the region 1275 to 1155 cm⁻¹ and 900–600 cm⁻¹ we could conclude that the samples from first two locations, Ro?ia Montan? and Nuf?ru, are made from amber of Baltic origin. In the case of the third location, Isaccea, we take into account the possibility of a mixture of raw materials, both Baltic and Romanian amber. These assertions are supported by statistical analysis and the historical context. Besides the FTIR spectra comparison or other analytical data, it is very important to correlate any information about the material (colour, conservation status, historical context, connections with other artefacts) and the statistical analysis in order to favour safe conclusions.     

文物彩绘常用胶料的氨基酸组成 及红外光谱特征研究

为了探索鉴定古代文物彩绘胶料的综合分析方法,使用红外光谱仪及氨基酸分析仪对中国古代五种常用文物彩绘胶料的红外吸收光谱及氨基酸组成进行了测定。通过对样品红外光谱特征吸收峰的判别、分析,得出了1653cm-1及1545cm-1处的吸收峰为蛋白类胶料的特征,1076cm-1及1043cm-1处的吸收峰为桃胶的特征,以及奶类同时具有蛋白类胶料及桃胶特征的结果。通过对样品氨基酸组成的分析,得出了动物胶特有羟脯氨酸及较多的甘氨酸,鸡蛋含有较高的天冬氨酸和较低的脯氨酸,奶类的谷氨酸和丙氨酸含量比较高的结果。研究结果表明,通过氨基酸分析结合红外光谱的特征吸收峰,可以基本区分、判定古代文物彩绘常用胶料归属的结论。     

Is vitrification in charcoal a result of high temperature burning of wood?

The term ‘vitrified’ is used to describe the glassy appearance of some charcoals recovered in the archaeological record. It has been generally considered that this phenomenon is a result of wood being subjected to high temperatures similar to the role of temperature in the formation of glass and pottery. Charcoals displaying characteristics of vitrification from three distinct archaeological contexts were analysed using reflectance microscopy to determine their temperature of formation. Charcoal was also generated in laboratory charring experiments at temperatures of 900–1100 °C for durations of 1, 6, 12 and 24 h to determine if subjection to high temperature led to vitrification. None of the laboratory-produced charcoals displayed characteristics of vitrification. Mean random reflectance of the vitrified archaeological fragments indicated temperature of formation from 310 to 530 °C. A charring experiment was also conducted, at 500 °C for 6 h, using green wood with some bark attached, and added sugars, but no evidence of vitrification was seen. Therefore vitrified charcoals do not result from high temperature charring or primarily from the use of green wood.     

EFFECTS OF DIFFERENT SAMPLE PREPARATION METHODS ON STABLE CARBON AND OXYGEN ISOTOPE VALUES OF BONE APATITE: A COMPARISON OF TWO TREATMENT PROTOCOLS*

Researchers have long debated the appropriateness of stable isotope analysis of bone apatite to reconstruct the diets of ancient animals. The debate has centred, in part, on diagenesis of bone mineral from interaction with the burial environment. A number of acetic acid treatments are used to remove diagenetic carbonates from samples; however, less is known on how different protocols alter stable isotope values. We compare two common acetic acid solution treatments (0.1 M versus 1.0 M-buffered) to examine the effects on carbon and oxygen isotope values and Fourier transform infrared spectroscopy (FTIR) spectra in human bone from different burial contexts. Results indicate that both treatments have a similar effect on isotope values and FTIR spectra in bone apatite.     

Burned bone in the Howieson’s Poort and post-Howieson’s Poort Middle Stone Age deposits at Sibudu (South Africa): behavioral and taphonomic implications

Despite a growing awareness of the wide range of information that can be provided by detailed analyses of burned bone from archaeological contexts, such analyses are still relatively uncommon. This paper focuses on the behavioral and taphonomic implications of burned bone from the Middle Stone Age (MSA) site of Sibudu Cave (South Africa), reporting on the analysis of a large sample (>377,000 fragments) of bone recovered from the Howieson’s Poort (HP) and post-HP MSA deposits at the site. Faunal remains were initially sorted into burning categories based on changes in color; microscopic analyses focused on the optical properties of the bone matrix (degree of preservation of the bone structure, reflectance and fluorescence) indicated that the color is a valid indicator of thermally altered bone in the Sibudu assemblage. The association of burned bone with hearths, the intensity of burning damage, and the sheer quantity of thermally altered bone suggests that the bone was not burned primarily as a result of natural fires. We propose that the high incidence of burned bone primarily reflects two types of site maintenance activities: first, the discarding of bone into fire as a means of disposing of food waste (as also argued by Cain [2005, Using burned animal bone to look at Middle Stone Age occupation and behavior. J. Archaeol. Sci. 32, 873–884], for a smaller sample of material from the post-HP and late MSA deposits at the site), and second, the incidental burning of bone on/near the surface during the periodic burning of plant-based bedding. In considering the taphonomic implications of the burned bone, we demonstrate that calcined bone is in fact more heavily fragmented than unburnt or moderately burned bone. Furthermore, cortical preservation was negatively correlated with the intensity of burning damage, which has implications for the study of surface modifications. These results indicate the importance of conducting thorough taphonomic analyses prior to making comparisons between units that show differing degrees or intensities of burning damage.     

Is X-ray diffraction able to distinguish between animal and human bones?

The possibility of determining the human or animal origin of bones from the lattice parameters of their inorganic bioapatite phase, when subjected to a high temperature treatment using the powder X-ray diffraction (XRD) technique, has been explored on a wide number of specimens. Forty-two animal bones were treated in a furnace at 1100 °C for 36 min and compared to 53 cremated human bones from a range of ancient necropolises. The X-ray diffraction patterns of bioapatite were simulated using both monoclinic P21/b and hexagonal P63/m structures to verify any occurrence of phase transformation and any difference in the lattice parameters due to the model. It was determined that the differences between the a-axis and c-axis of the monoclinic and hexagonal lattice were unimportant. Some outlying values were revealed to be caused by the presence of chlorine ions diffused into the apatite structure increasing its average unit cell values. Nevertheless, our results clearly show that in terms of lattice parameters the variability of human specimens are completely overlapped by the non-human variability making the use of XRD in order to distinguish animal from human bones questionable.     

Experimental micromorphology in Tierra del Fuego (Argentina): building a reference collection for the study of shell middens in cold climates

Commonly used in archaeological contexts, micromorphology did not see a parallel advance in the field of experimental archaeology. Drawing from early work conducted in the 1990’s on ethnohistoric sites in the Beagle Channel, we analyze a set of 25 thin sections taken from control features and experimental tests. The control features include animal pathways and environmental contexts (beach samples, forest litter, soils from the proximities of archaeological sites), while the experimental samples comprise anthropic structures, such as hearths, and valves of Mytilus edulis (the most important component of shell middens in the region) heated from 200 °C to 800 °C. Their micromorphological study constitutes a modern analogue to assist archaeologists studying site formation and ethnographical settings in cold climates, with particular emphasis on shell midden contexts.     

Accessing Hunter-Gatherer site structures using Fourier transform infrared spectroscopy: applications at a Taltheilei settlement in the Canadian Sub-Arctic

The results of Fourier transform infrared spectroscopy on soils and caribou bone from a Taltheilei culture settlement in northern Canada contribute to developing micro-archaeological approaches suitable for locating and characterizing hearth and midden features on hunter-gatherer sites. A weak yet pervasive signal for montgomeryite was developed from the diagenesis of dispersed ash and caribou processing residues. Disordered calcite, carbonate hydroxylapatite, charcoal, and burned bone in two pit-house hearth deposits indicate that both wood and bone were used for fuel. Crystallinity indices and carbonate/phosphate ratios for bone indicate high intensity burning. These data, in tandem with the presence of semi-subterranean dwellings, demonstrate that this particular tundra-based encampment was occupied during cold seasons, a type of settlement behaviour previously unrecognized in the Taltheilei archaeological record. Our results confirm that Fourier transform infrared spectroscopy is an accessible, rapid, and cost effective means of discovering micro-archaeological evidence valuable for reconstructing hunter-gatherer site structures.     

Charcoal reflectance measurements: implications for structural characterization and assessment of diagenetic alteration

Charcoal is a valuable source of archaeological and palaeoenvironmental proxy data. However growing evidence suggests that production conditions can strongly influence post-depositional alteration of charcoal. Consequently, both reconstruction of production temperature and understanding of the potential for diagenetic alteration are of great interest. Here, we use mean random reflectance (Ro_mean) in conjunction with other chemical characterization methods to address these questions. Ro_mean was obtained for a suite of modern analogue charcoal, produced under controlled conditions, and for a series of natural charcoal samples, obtained from archaeological and palaeoenvironmental deposits. Ro_mean proves to be a robust measure to assess formation temperature for samples produced at 400 °C and above, even after exposure to highly oxidizing conditions. Ro_mean is also useful for samples formed between 300 °C and 400 °C. However, if an assemblage of charcoals has been exposed to oxidizing conditions, lower temperature charcoals may be preferentially lost. It is apparent that charcoal produced at lower temperatures is more highly susceptible to chemical oxidation, and that there is a continuum in charcoal degradation potential, dependant upon fuel material and production conditions.     

Characterisation and blind testing of radiocarbon dating of cremated bone

The success of radiocarbon dating of burned or cremated bones depends on the exposed temperature during burning and the degree of re-crystallisation of the inorganic bone matrix. We present a method for characterisation of likely cremated bones by employing visual inspection, infrared spectrometry and carbon stable isotope analysis on the bio-apatite fraction. The method of radiocarbon dating of cremated bones was tested by dating paired samples of bone and associated context materials such as pitch, charcoal and a dendrochronologically dated oak coffin. The dating of these paired test samples were largely performed as blind tests and showed excellent agreement between pitch and bone. The weighted mean age difference of all test samples is observed to −9 ± 60 ¹⁴C yr. To test the indicators and the effects of the degree of burning, a Late-Neolithic human individual has been studied, as this individual exhibits the full spectrum from low temperature burning (charred) to high temperature (“cremated”) from one end of a single bone to the other. This is reflected as a marked step in numerous parameters as well as in a significant difference in ¹⁴C age between the charred and the cremated bone samples.