Exogenous carbonaceous contaminants coming from sediments significantly bias the radiocarbon date of collagen samples extracted from archaeological bone and teeth. In this study, a new approach ...combining pyrolysis, comprehensive gas chromatography and mass spectrometry (Py-GC × GC/MS) was proposed to ensure their removal during the demineralization and bone collagen extraction. This approach permitted to identify hydrocarbon contaminants for archaeological samples from the Neolithic period, in 30–40 μg of collagen. The use of 2D GC improved importantly the separation, selectivity and resolution compared to 1D GC thus permitting to detect organic contaminants within the complex chromatograms issued from collagen pyrolysis. Moreover, efficiency of the extraction steps in collagen sample preparation for radiocarbon dating (acid and alkali treatments, filtration steps) could be evaluated for four different protocols on the basis of organic contaminant removal. Radiocarbon dating of the extracted collagen of four of the tested protocols corroborated the results of the Py GC × GC/MS data. This approach opens new perspectives for the use of comprehensive gas chromatography in the domain of archaeological sciences.
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•Soil contaminants in archaeological collagen may be detected upstream.•Collagen extraction protocols are differently effective for removing contaminants.•Py-GCxGC/MS is efficient to assess contaminant persistence and collagen preservation.
Collagen glue has been used for nearly two centuries to consolidate bone material, although its prevalence in museum collections is only now becoming visible. Identifying and removing collagen glue ...is crucial before the execution of any geochemical or molecular analyses. Palaeolithic bone objects from old excavations intended for radiocarbon dating were first analysed using ZooMS (Zooarchaeology by Mass Spectrometry) to identify the animal species, however peaks characteristic of both cattle and whale were discovered. Two extraction methods for ZooMS were tested to identify the authentic animal species of these objects, which revealed that these were originally whale bone objects that had been consolidated with cattle collagen glue. This is the first time animal collagen glue has been identified in archaeological remains with ZooMS, illustrating again the incredible versatility of this technique. Another technique, Fourier Transform Infrared Spectroscopy in Attenuated Total Reflectance mode (FTIR-ATR), was also tested if it could rapidly identify the presence of collagen glue in archaeological bone material, which was not the case. Two other cleaning methods were tested to remove bone glue contamination prior to radiocarbon dating, along with two modified collagen extraction methods for ZooMS. These methods were applied to bone blank samples (FmC = 0.0031 ± 0.0002, (n = 219), 47 336 ± 277 yr BP) that were experimentally consolidated with collagen glue and to the Palaeolithic bone material (ca. 15 000 and 12 000 yr BP). The experimental bone blanks produced excellent
C ages, suggesting the cleaning methods were successful, however the
C ages for some of the Palaeolithic material remained too young considering their contextual age, suggesting that the collagen glue contamination had most likely cross-linked to the authentic collagen molecule. More research is needed in order to gain a deeper understanding of the occurrence and elimination of cross-linked collagen-based glues in material from museum collections.
Bone remains of small vertebrate fossils provide valuable information for paleoenvironmental and paleoclimatic reconstructions. However, direct radiocarbon dating of small vertebrates remains ...challenging as the extraction of sufficient good quality collagen is required. The efficiency of eight collagen extraction protocols was tested on seven samples, representative of different ages and burial environments, including both macro and small vertebrate taxa. First, the samples were prescreened using attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) to quantify collagen content in archaeological bones, revealing that one should be discarded for 14C dating. Then, the quantity of protein extracted (yield) and collagen integrity were checked using conventional elemental analysis. The results show that one protocol was not able to accurately extract collagen from the samples. A soft HCl-based protocol seems more appropriate for the pretreatment of archaeological small mammal bones, whereas a harsher protocol might be more efficient to extract a higher amount of collagen from large mammals as well as amphibian bones. The influence of the tested protocols on carbon and nitrogen isotope values was also investigated. The results showed that isotopic variability, when existing, is related to the interindividual differences rather than the different protocols.
Because hard tissues can be radiocarbon dated, they are key to establishing the archaeological chronologies, palaeoenvironmental reconstructions and historical-biogeographical processes of the last ...50,000 years. The advent of accelerator mass spectrometers (AMS) has revolutionized the field of archaeology but routine AMS dating still requires 60-200 mg of bone, which far exceeds that of small vertebrates or remains which hold a patrimonial value (e.g. hominid remains or worked bone artefacts). Here, we present the first radiocarbon dates obtained from minute amounts of bone (3-60 mg) using a MIni CArbon DAting System (MICADAS). An optimized protocol allowed us to extract enough material to produce between 0.2 and 1.0 mg of carbon for graphite targets. Our approach was tested on known-age samples dating back to 40,000 BP, and served as proof of concept. The method was then applied to two archaeological sites where reliable dates were obtained from the single bones of small mammals. These results open the way for the routine dating of small or key bone samples.
Abstract
Conservation of the preserving medium is an essential element for the proper preservation of specimens in fluid collections. However, the preservatives can become chemically altered over ...time or be lost by processes such as evaporation. To combat such changes and properly care for and maintain immersed specimens, it is therefore necessary to know what preservative fluid was initially chosen and how its chemistry may have evolved with time. The present work explores the possibilities offered by Raman spectrometry for a rapid, nondestructive, noninvasive alternative to commonly employed chemical identification tests, which are often limited to the identification of simple fluids. In a first step, fluids were reconstituted and analyzed in small standard glass containers to evaluate the potential of the technique. Then we successfully applied the procedure to real cases and considered its possible use to estimate the concentration of ethanol and to detect small quantities of formaldehyde (down to 1%). The results demonstrate the power of this technique, which opens up new possibilities for the management of fluid collections.
En 2010, la fondation Institut de paléontologie humaine (Paris) a acquis un squelette monté de rhinocéros laineux, Coelodonta antiquitatis (Blumenbach, 1799), dont le remarquable état de conservation ...a permis une étude pluridisciplinaire : analyses anatomique, biométrique, géochronologique (datations par le carbone-14 par AMS de la corne et de certains os) et biogéochimique (reconstitution de la paléoalimentation et du paléoenvironnement par la méthode des isotopes du carbone et de l’azote). Une recherche sur l’origine de ce spécimen et son parcours avant son acquisition a également été menée. Ces différentes investigations nous ont conduits à préciser l’identification spécifique du fossile sibérien, son âge biologique et son sexe, ainsi que son attribution chronologique et son comportement alimentaire.
In 2010, the foundation Institut de paléontologie humaine (Paris) acquired an assembled skeleton of woolly rhinoceros, Coelodonta antiquitatis (Blumenbach, 1799). Its exceptional state of preservation allowed a multidisciplinary study: anatomical, biometrical, geochronological (AMS radiocarbon dating on horn and some bones) and biogeochemical analyses (reconstruction of the palaeodiet and the palaeoenvironment using the method of carbon and nitrogen isotopes). A research about the origin of this specimen and its story before its acquisition was also carried out. These different investigations led us to precise the species identification of this Siberian fossil, its biological age and its gender, as well as its chronological attribution and its dietary behavior.
The house mouse (Mus musculus) represents the extreme of globalization of invasive mammals. However, the timing and basis of its origin and early phases of dispersal remain poorly documented. To ...track its synanthropisation and subsequent invasive spread during the develoment of complex human societies, we analyzed 829 Mus specimens from 43 archaeological contexts in Southwestern Asia and Southeastern Europe, between 40,000 and 3,000 cal. BP, combining geometric morphometrics numerical taxonomy, ancient mitochondrial DNA and direct radiocarbon dating. We found that large late hunter-gatherer sedentary settlements in the Levant, c. 14,500 cal. BP, promoted the commensal behaviour of the house mouse, which probably led the commensal pathway to cat domestication. House mouse invasive spread was then fostered through the emergence of agriculture throughout the Near East 12,000 years ago. Stowaway transport of house mice to Cyprus can be inferred as early as 10,800 years ago. However, the house mouse invasion of Europe did not happen until the development of proto urbanism and exchange networks - 6,500 years ago in Eastern Europe and 4000 years ago in Southern Europe - which in turn may have driven the first human mediated dispersal of cats in Europe.
Ancient bone proteins provide a plethora of information regarding the identity, period, and diet/environment of animal species through proteomic analysis, radiocarbon dating and isotopic analysis ...respectively. However, each technique imposes specific constraints for bone protein extraction. Despite the sample preciousness and heterogeneity, these analyses are not routinely performed on the same aliquot. Protocol for radiocarbon dating are the most restrictive in terms of sample preparation and their effects have seldom been evaluated at the molecular level. Here, several extraction protocols were tested using modern and archaeological bones. Molecular characterization of the extracts was performed using electrophoresis and proteomics. Protocol-induced biases in peptide sequences and their effect on species identification were evaluated using database searching and partial de novo sequencing. This work shows that extraction protocols corresponding to mild bone decalcification conditions and using ultrafiltration are the most suitable for species identification.
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•Molecular characterization of bone proteins extracted following eight different radiocarbon dating protocols.•High influence of extraction protocols on collagen integrity.•Softer protocols and ultrafiltration are better suited for palaeoproteomics.
The analysis of the skeletal remains of vertebrates in archaeological contexts provides information about human-animal relationship and their environment. Their taxonomic identification based on ...macroscopic observation is not always possible due to fragmentation and poor preservation. In recent years, proteomics has emerged as an alternative but there is clearly a lack of data in arid environment where diagenesis rapidly affects the integrity of bone proteins. Here, we report the efficiency of three protocols for protein extraction. The protocols used harsh (1 M HCl and 0.6 M HCl) and soft (Tris-EDTA) decalcification agents and were tested on unidentified splinters from the 2000 years-old site of Toteng, Botswana. The preservation of the organic phase was first estimated using attenuated total reflectance Fourier transform infrared spectroscopy and a set of samples with contrasted collagen contents were selected for palaeoproteomics. The extracted proteins were submitted to a bottom-up proteomic approach involving trypsin digestion followed by ultra-high-performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). Our results identify Tris-EDTA buffer as the most suitable decalcification protocol for poorly preserved bones and propose a collagen content threshold of ~3% weight content for successful detection of peptides. This approach, combined with biogeographical and chronological repartitions of mammals in Africa allows refining taxonomic attributions for four out of nine splinters, leading to species identification. Data are available via ProteomeXchange with identifier PXD010725.
•Tris-EDTA buffer is identified as best decalcification agent for palaeoproteomics analyses of splinters from Botswana.•ATR-FTIR prescreening threshold of collagen preservation is proposed for palaeoproteomics samples selection.•Combination of palaeoproteomics and chrono-biogeographical repartitions of African mammals allowed species identification.
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