Widespread exploitation of the honeybee by early Neolithic farmers.

The pressures on honeybee (Apis mellifera) populations, resulting from threats by modern pesticides, parasites, predators and diseases, have raised awareness of the economic importance and critical role this insect plays in agricultural societies across the globe. However, the association of humans with A. mellifera predates post-industrial-revolution agriculture, as evidenced by the widespread presence of ancient Egyptian bee iconography dating to the Old Kingdom (approximately 2400 BC). There are also indications of Stone Age people harvesting bee products; for example, honey hunting is interpreted from rock art in a prehistoric Holocene context and a beeswax find in a pre-agriculturalist site. However, when and where the regular association of A. mellifera with agriculturalists emerged is unknown. One of the major products of A. mellifera is beeswax, which is composed of a complex suite of lipids including n-alkanes, n-alkanoic acids and fatty acyl wax esters. The composition is highly constant as it is determined genetically through the insect's biochemistry. Thus, the chemical 'fingerprint' of beeswax provides a reliable basis for detecting this commodity in organic residues preserved at archaeological sites, which we now use to trace the exploitation by humans of A. mellifera temporally and spatially. Here we present secure identifications of beeswax in lipid residues preserved in pottery vessels of Neolithic Old World farmers. The geographical range of bee product exploitation is traced in Neolithic Europe, the Near East and North Africa, providing the palaeoecological range of honeybees during prehistory. Temporally, we demonstrate that bee products were exploited continuously, and probably extensively in some regions, at least from the seventh millennium cal BC, likely fulfilling a variety of technological and cultural functions. The close association of A. mellifera with Neolithic farming communities dates to the early onset of agriculture and may provide evidence for the beginnings of a domestication process.

Differences in birch tar composition are explained by adhesive function in the central European Iron Age.

Birch bark tar is the most widely documented adhesive in prehistoric Europe. More recent periods attest to a diversification in terms of the materials used as adhesives and their application. Some studies have shown that conifer resins and beeswax were added to produce compound adhesives. For the Iron Age, no comparative large-scale studies have been conducted to provide a wider perspective on adhesive technologies. To address this issue, we identify adhesive substances from the Iron Age in north-eastern France. We applied organic residue analysis to 65 samples from 16 archaeological sites. This included residues adhering to ceramics, from vessel surface coatings, repaired ceramics, vessel contents, and adhesive lumps. Our findings show that, even during the Iron Age in north-eastern France, birch bark tar is one of the best-preserved adhesive substances, used for at least 400 years. To a lesser extent, Pinaceae resin and beeswax were also identified. Through statistical analyses, we show that molecular composition differs in samples, correlating with adhesive function. This has implications for our understanding of birch bark tar production, processing and mode of use during the Iron Age in France and beyond.

Investigating grandmothers' cooking: A multidisciplinary approach to foodways on an archaeological dump in Lower Casamance, Senegal.

Because they hold information about cultural identity, foodways have been the focus of a variety of disciplines in archaeology. However, each approach documents different stages of culinary preparation and is constrained by the preservation specificities of each type of artefact and ecofact. Difficulties in achieving an interdisciplinary approach may explain the scarcity of such studies. In this paper, we propose a methodology that combines archaeozoological, carpological and microbotanical analysis of ecofacts retrieved in the sediment, with use-alteration, organic residue and microbotanical analysis carried out on pottery vessels, recovered during the excavation of a XXth century archaeological dump site in Lower Casamance (Senegal). The results demonstrate the strength of this multiproxy approach in reconstructing past foodways by characterising the importance of aquatic, terrestrial animals and plant products in the Diola Kassa diet. In addition, this study questions the modalities of food transformation by assessing the preparation techniques of animal and vegetal products (cutting marks, heating processes etc.) and the function of pottery vessels (transport, storage, cooking etc.). Aquatic products and rice were a significant part of the diet of the users of the dump (from archaeozoology, carpology, phytoliths and organic residue analysis) and wet cooking (boiling?), salty and acidic foods seem to have been particularly prevalent (from use-alteration). The absence of specific animal and plant parts in the archaeological record, as well as some pottery function, is also questioned. Beyond gathering the results of each approach, this study focuses on the interweaving of different research methods to depict past foodscape.

Alteration of Asian lacquer: in-depth insight using a physico-chemical multiscale approach.

Oriental lacquer has been used in Asian countries for thousands of years as a durable and aesthetic coating material for its adhesive, consolidating, protective and decorative properties. Although these objects are made from an unusual material in Occident, Western museum collections host many lacquerwares. Curators, restorers and scientists are daily confronted with questions of their conservation and their alteration. The characterization of their conservation state is usually assessed through visual observations. However deterioration often starts at the microscopic level and cannot be detected by a simple visual inspection. Often, ageing and deterioration of artworks are connected to physical, mechanical and chemical transformations. Thus new insight into alteration of lacquer involves the monitoring of macro-, microscopic and molecular modifications, and this can be assessed from physico-chemical measurements. Non-invasive (microtopography and Scanning Electron Microscopy - SEM) and micro-invasive (infrared micro-spectroscopy using a synchrotron source - SR-µFTIR) investigations were performed to study the degradation processes of lacquers and evaluate their level of alteration. In particular, spectral decomposition and fitting procedure were performed in the 1820-1520 cm(-1) region to follow the shift of the C=O and C=C band positions during lacquer ageing. The present work proves the potential of this physico-chemical approach in conservation studies of lacquers and in the quantification of the state of alteration. It evidences chemical phenomena of alteration such as oxidation and decomposition of a lacquer polymeric network. It also demonstrates for the first time the degradation front of artificially aged lacquer and the chemical imaging of a more than 2000 years old archaeological lacquer by using SR-µFTIR.

First identification of an evolving Middle Stone Age ochre culture at Porc-Epic Cave, Ethiopia.

The use of mineral pigments, in particular iron-rich rocks, holds significant importance in understanding the emergence and evolution of human cultures. However, sites that have yielded a number of pieces large enough to precisely identify how the use of this material changed through time are rare. In this study, we examine one of the largest known Middle Stone Age (MSA) ochre collections, from Porc-Epic Cave, Ethiopia, consisting of more than 40 kg of ochre (n = 4213 pieces), 21 ochre processing tools and two ochre-stained artefacts. By combining the analysis of the elemental and mineralogical composition of the archaeological material with that of natural ochre collected in the surroundings of the site, and correlating this information with shifts in ochre modification techniques over time, we unveil how MSA inhabitants of Porc-Epic Cave exploited mineral resources. We show that they could predict the properties of different ochre types accessible in their environment, and gradually adapted their technology to cope with changes in raw material availability. Furthermore, the analysis of ochre residues on a painted pebble, likely used to produce red dots on a surface, identifies an ochre type that was specifically employed for symbolic purposes.

First chemical evidence of royal purple as a material used for funeral treatment discovered in a Gallo-Roman burial (Naintré, France, third century AD).

Violet-purple residues collected from a Gallo-Roman burial dated back to the second half of the third century A.D. and excavated at Naintré (France) were chemically investigated by multi-analytical methodology involving the use of Raman spectroscopy, direct exposure-mass spectrometry (DE-MS) and high-performance liquid chromatography (HPLC-UV-visible). Little is known about funeral treatment and rituals during Roman times. Retrieving valuable information on these by chemical analysis of organic residues was thus a key aspect of this work. Analyses demonstrated the presence of the very precious purple colorant obtained from shellfish glands commonly known as Tyrian or royal purple and its exceptional preservation. Chemical investigation and archaeological evidence have shown that purple was widely spread after the deposition of the body for burial. These results are the earliest chemical evidence of purple colorant used during funeral rituals (not as textile dye) and enabled us to highlight new aspects of funeral practices in Roman times.

Advanced discriminating criteria for natural organic substances of cultural heritage interest: spectral decomposition and multivariate analyses of FT-Raman and FT-IR signatures.

Natural organic substances are involved in many aspects of the cultural heritage field. Their presence in different forms (raw, heated, mixed), with various conservation states, constitutes a real challenge regarding their recognition and discrimination. Their characterization usually involves the use of separative techniques which imply destructive sampling and specific analytical preparations. Here we propose a non destructive approach using FT-Raman and infrared spectroscopies for the identification and differentiation of natural organic substances. Because of their related functional groups, they usually present similar vibrational signatures. Nevertheless the use of appropriate signal treatment and statistical analysis was successfully carried out to overcome this limitation, then proposing new objective discriminating methodology to identify these substances. Spectral decomposition calculations were performed on the CH stretching region of a large set of reference materials such as resins, oils, animal glues, and gums. Multivariate analyses (Principal Component Analyses) were then performed on the fitting parameters, and new discriminating criteria were established. A set of previously characterized archeological resins, with different surface aspects or alteration states, was analyzed using the same methodology. These testing samples validate the efficiency of our discriminating criteria established on the reference corpus. Moreover, we proved that some alteration or ageing of organic materials is not an issue to their recognition.

Molecular criteria for discriminating museum Asian lacquerware from different vegetal origins by pyrolysis gas chromatography/mass spectrometry.

This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis-methylation (THM) pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis that can be carried out with a minimum amount of matter (typically 10 µg for a sample collected on a museum or an archaeological object). The main contribution of this study is to provide multiple molecular criteria for discriminating the three Asian species used for making lacquers, namely Rhus verniciflua Stokes, Rhus succedanea and Melanorrhoea usitata. Because these trees grow in specific areas, identifying the species involved in ancient lacquer coatings also provides geobotanical data and fruitful information on the exchange networks and trading routes developed by ancient societies. With this purpose, a systematic study of all pyrolysis products of lacquer coatings was carried out on modern dried lacquer films from authentified provenance. It was demonstrated that the whole pyrolysis products play a significant role in identifying the vegetal species. The chemotaxonomic value of homologous series of alkanes, alkenes and benzene derivatives, rarely explored until now, was assessed. It was shown that the combination of data related to five distinct groups of pyrolytic markers (composition and/or distribution of alkanes, alkenes and benzene, alkenyl-, alkylcatechol and phenol derivatives) provided new strong criteria to establish vegetal origin and provenance of Asian artworks, even though they have been largely altered over time. Case studies of archaeological Chinese lacquered artefacts and Japanese Buddhistic altar were thereafter successfully investigated to address informative potential and efficiency of these criteria on ancient and degraded lacquer coatings.

Molecular criteria for discriminating adipose fat and milk from different species by NanoESI MS and MS/MS of their triacylglycerols: application to archaeological remains.

A new multistep analytical methodology is described in this paper for the precise identification of triacylglycerols, which are biomarkers of dairy products and subcutaneous fats, that may be chemically identified in archaeological pottery. It consists of the analysis of the total lipid extract from different kinds of fats by high-temperature gas chromatography, performed in order to select the ceramic vessels in which animal fats are well preserved, followed by nanoelectrospray QqTOF mass spectrometry that allows for distinguishing the specific origins of the lipids detected (namely, cow, sheep, or goat). The analysis of model samples, cow and goat dairy products and cow and sheep adipose fats, was successfully achieved. The fatty acid composition of each triacylglycerol was identified, which allowed for the discrimination of subcutaneous fats and dairy fats and distinguishing between cow and goat milk. This methodology was then applied to archaeological samples, and the presence of goat milk, cow milk, and possibly sheep subcutaneous fat was assessed based on the discriminating criteria found on modern fats.

Investigating the history of prehistoric glues by gas chromatography-mass spectrometry.

Although organic materials are very sensitive to biochemical alteration processes, they may be preserved for millennia in various archaeological contexts. Remains of adhesives made during prehistory were discovered at different sites, in the form of residues adhering to flint tools and ceramic vessels or as free lumps in sediment. To characterise the natural substances exploited for adhesive production during late prehistory, we undertook GC and GC/MS analysis of 90 samples from 8 sites dating from the Neolithic to Iron Age periods. This paper discusses our approach to the study of organic adhesives preserved in archaeological contexts, with a particular focus on the presentation of the various categories of organic adhesives that we analysed and the choice of chromatographic conditions adapted to the specificity of such samples. The results obtained show that birch bark tar, a triterpenoid adhesive made by destructive distillation of white birch bark, was predominantly used during the neolithic period even though other materials such as various barks or organic fossil substance were also used. During the Bronze and Iron ages, which follow the Neolithic period, adhesive production is evolving through the expansion of the range of the natural substances used (identification of diterpenoid pine resin) and the addition of beeswax as a plasticiser to birch bark tar. By combining chromatographic analysis and archaeological data, it was thus possible to follow the evolution of adhesive making at the end of prehistory, testifying to the inventiveness of the craftsmen whatever the period considered.

Identification of archaeological adhesives using direct inlet electron ionization mass spectrometry.

Adhesives made from natural substances such as resins, tars, and waxes are found during excavations on archaeological sites dating back to prehistoric periods. Until now, their analysis was mainly performed by gas chromatography, possibly coupled to mass spectrometry, after extraction, purification, and derivatization of the samples. To minimize sampling and sample preparation of ancient organic remains, which are often preserved in tiny amounts, we have directly analyzed archaeological samples from Bronze and Iron Age periods by direct inlet electron ionization mass spectrometry. A series of contemporary natural and synthetic substances, including pine and pistacia resins, birch bark tar, beeswax, and plant oils, possibly used for adhesive fabrication during ancient times, was also investigated with the same technique as reference materials. Despite the complexity of their chemical composition, pine resin and birch bark tar were clearly identified in archaeological samples. Furthermore, mass spectrometry has been shown to be efficient for the identification of glues made of a mixture of beeswax, presenting a series of mass spectral peaks assigned to long-chain esters, and birch bark tar, whose mass spectrum presents characteristic peaks of lupane compounds. The intentional mixing of birch bark tar and beeswax during prehistory is reported here for the first time.

Characterization of archaeological beeswax by electron ionization and electrospray ionization mass spectrometry.

To better detect and identify beeswax in ancient organic residues from archaeological remains, we developed a new analytical methodology consisting of the analysis of (i) the trimethylsilylated organic extract by GC/MS and (ii) the crude extract by ESI-MS. Selective scanning modes, such as SIM or MRM, permit separate quantification of each chemical family (fatty acids, monoesters, monohydroxyesters, and diesters) and allow an improvement in sensitivity and selectivity, allowing the crude extract to be treated without further purification. GC/MS (SIM) was revealed to be a powerful method for the detection of components, with a detection limit down to a total lipid extract in the range of approximately 50 ng in a complex matix, such as archaeological degraded material, whereas ESI-MS/MS is instead used for the detection of nonvolatile biomarkers. Identification by GC/MS (SIM) and ESI-MS/ MS (MRM) of more than 50 biomarkers of beeswax in an Etruscan cup at the parts-per-million level provides the first evidence for the use of this material by the Etruscans as fuel or as a waterproof coating for ceramics.