Ilaria Degano

Early evidence of San material culture represented by organic artifacts from Border Cave, South Africa

Recent archaeological discoveries have revealed that pigment use, beads, engravings, and sophisticated stone and bone tools were already present in southern Africa 75,000 y ago. Many of these artifacts disappeared by 60,000 y ago, suggesting that modern behavior appeared in the past and was subsequently lost before becoming firmly established. Most archaeologists think that San hunter–gatherer cultural adaptation emerged 20,000 y ago. However, reanalysis of organic artifacts from Border Cave, South Africa, shows that the Early Later Stone Age inhabitants of this cave used notched bones for notational purposes, wooden digging sticks, bone awls, and bone points similar to those used by San as arrowheads. A point is decorated with a spiral groove filled with red ochre, which closely parallels similar marks that San make to identify their arrowheads when hunting. A mixture of beeswax, Euphorbia resin, and possibly egg, wrapped in vegetal fibers, dated to ∼40,000 BP, may have been used for hafting. Ornaments include marine shell beads and ostrich eggshell beads, directly dated to ∼42,000 BP. A digging stick, dated to ∼39,000 BP, is made of Flueggea virosa. A wooden poison applicator, dated to ∼24,000 BP, retains residues with ricinoleic acid, derived from poisonous castor beans. Reappraisal of radiocarbon age estimates through Bayesian modeling, and the identification of key elements of San material culture at Border Cave, places the emergence of modern hunter–gatherer adaptation, as we know it, to ∼44,000 y ago.

Analytical Methods for the Characterization of Organic Dyes in Artworks and in Historical Textiles

Abstract Dyes are among the most significant components in works of art and archaeological findings. In the scientific examination of historical artefacts, the identification of natural dyestuffs is a challenging task, due to the complexity of their chemical composition and the possible presence of mixtures of chromophores and degradation products. For this reason, in the last few decades, new analytical procedures and techniques have been developed and improved for the characterization of organic dyes and their identification in microsamples. This review looks at the chemical composition of natural organic dyeing materials used in the field of the cultural heritage and focuses on several analytical methods based on spectrometric and chromatographic techniques that have contributed to the study of organic dyes in works of art and archaeological findings.

Border Cave and the beginning of the Later Stone Age in South Africa

The transition from the Middle Stone Age (MSA) to the Later Stone Age (LSA) in South Africa was not associated with the appearance of anatomically modern humans and the extinction of Neandertals, as in the Middle to Upper Paleolithic transition in Western Europe. It has therefore attracted less attention, yet it provides insights into patterns of technological evolution not associated with a new hominin. Data from Border Cave (KwaZulu-Natal) show a strong pattern of technological change at approximately 44–42 ka cal BP, marked by adoption of techniques and materials that were present but scarcely used in the previous MSA, and some novelties. The agent of change was neither a revolution nor the advent of a new species of human. Although most evident in personal ornaments and symbolic markings, the change from one way of living to another was not restricted to aesthetics. Our analysis shows that: (i) at Border Cave two assemblages, dated to 45–49 and >49 ka, show a gradual abandonment of the technology and tool types of the post-Howiesons Poort period and can be considered transitional industries; (ii) the 44–42 ka cal BP assemblages are based on an expedient technology dominated by bipolar knapping, with microliths hafted with pitch from Podocarpus bark, worked suid tusks, ostrich eggshell beads, bone arrowheads, engraved bones, bored stones, and digging sticks; (iii) these assemblages mark the beginning of the LSA in South Africa; (iv) the LSA emerged by internal evolution; and (v) the process of change began sometime after 56 ka.

The oxidation of natural flavonoid quercetin

This study explains the controversies in the literature concerning the number of electrons involved in the oxidation of quercetin. This stems from inappropriate handling samples, which require strict anaerobic conditions. The redox potential of quercetin strongly depends on the pH and on the presence of dissociation forms in solution.

On the stability of the bioactive flavonoids quercetin and luteolin under oxygen-free conditions

AbstractThe natural flavonoid compounds quercetin (3,3′,4′,5,7-pentahydroxyflavone) and luteolin (3′,4′,5,7-tetrahydroxyflavone) are important bioactive compounds with antioxidative, anti-allergic, and anti-inflammatory properties. However, both are unstable when exposed to atmospheric oxygen, which causes degradation and complicates their analytical determinations. The oxidative change of these flavonoids was observed and followed by UV–visible spectrophotometry, both in aqueous and ethanolic solutions. The distribution of the degradation products in aqueous media was monitored by LC–MS and LC–DAD analysis. The amounts of oxidative reaction products increase with the exposure time. The oxidative degradation reduces the pharmacological efficiency of these antioxidants and renders analytical determination inaccurate. The oxidative changes in flavonoid test solutions can explain the inconsistent dissociation constants reported in the literature. Dissociation constants of quercetin and luteolin were determined both by alkalimetric titration and by UV–visible spectrophotometry under deaerated conditions. The values pK1 = 5.87 ± 0.14 and pK2 = 8.48 ± 0.09 for quercetin, and pK1 = 5.99 ± 0.32 and pK2 = 8.40 ± 0.42 for luteolin were found. FigureThe change of absorption spectra of quercetin during the exposure to the air oxygen

The Still Bay and Howiesons Poort at Sibudu and Blombos: Understanding Middle Stone Age Technologies

The classification of archaeological assemblages in the Middle Stone Age of South Africa in terms of diversity and temporal continuity has significant implications with respect to recent cultural evolutionary models which propose either gradual accumulation or discontinuous, episodic processes for the emergence and diffusion of cultural traits. We present the results of a systematic technological and typological analysis of the Still Bay assemblages from Sibudu and Blombos. A similar approach is used in the analysis of the Howiesons Poort (HP) assemblages from Sibudu seen in comparison with broadly contemporaneous assemblages from Rose Cottage and Klasies River Cave 1A. Using our own and published data from other sites we report on the diversity between stone artifact assemblages and discuss to what extent they can be grouped into homogeneous lithic sets. The gradual evolution of debitage techniques within the Howiesons Poort sequence with a progressive abandonment of the HP technological style argues against the saltational model for its disappearance while the technological differences between the Sibudu and Blombos Still Bay artifacts considerably weaken an interpretation of similarities between the assemblages and their grouping into the same cultural unit. Limited sampling of a fragmented record may explain why simple models of cultural evolution do not seem to apply to a complex reality.

A Milk and Ochre Paint Mixture Used 49,000 Years Ago at Sibudu, South Africa

Gas chromatography/mass spectrometry, proteomic and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) analyses of residue on a stone flake from a 49,000 year-old layer of Sibudu (South Africa) indicate a mixture of ochre and casein from milk, likely obtained by killing a lactating wild bovid. Ochre powder production and use are documented in Middle Stone Age South African sites but until now there has been no evidence of the use of milk as a binder. Our analyses show that this ochre-based mixture was neither a hafting adhesive nor a residue left after treating animal skins, but a liquid mixture consisting of a powdered pigment mixed with milk; in other words, a paint medium that could have been applied to a surface or to human skin. The significance of our finds also lies in the fact that it establishes the antiquity of the use of milk as a binder well before the introduction of domestic cattle in South Africa in the first millennium AD.

Core shell stationary phases for a novel separation of triglycerides in plant oils by high performance liquid chromatography with electrospray-quadrupole-time of flight mass spectrometer.

A new method for the analysis of triglycerides (TAGs) in vegetable oils was developed using a Poroshell 120 EC-C18 column (3.0 mm×50 mm, 2.7 μm) with a high resolution ESI-Q-ToF tandem mass spectrometer as detection system. We used an Agilent Poroshell column, which is characterized by a recently developed stationary phase based on non-porous core particles. The results highlighted the advantages of this column in terms of the dramatic improvement in the number of theoretical plates and in low column backpressure. The developed method enabled us to analyze complex mixtures of more than 40 TAGs within less than 25 min and with a low backpressure (lower than 100 bar), and represents the first application of a core-shell stationary phase in reverse phase HPLC using an ESI-Q-ToF as detection system. The method was optimized on standards of TAGs, validated and applied to several plant oils. By a quantitative point of view, the method showed a very good linearity (r(2)>0.999) in the range 0.1-2.4 μg/g; high intra- and inter-day precision both in terms of retention times (RSD%<0.04%) and peak areas (RSD%<0.3%). Limits of detection and quantitation were lower than 0.03 μg/g and 0.10 μg/g, respectively.

Py-GC/MS applied to the analysis of synthetic organic pigments: characterization and identification in paint samples

AbstractA collection of 76 synthetic organic pigments was analysed using pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The purpose of this work was to expand the knowledge on synthetic pigments and to assess characteristic pyrolysis products that could help in the identification of these pigments in paint samples. We analysed several classes of synthetic pigments not previously reported as being analysed by this technique: some metal complexes, β-naphthol pigment lakes, BONA pigment lakes, disazopyrazolone, triarylcarbonium, dioxazine, anthraquinone, indanthrone, isoindoline and thioindigo classes. We also report for the first time the Py-GC/MS analysis of a number of naphthol AS, benzimidazolone, phthalocyanine and perylene pigments and other miscellaneous pigments including pigments with unpublished chemical structure. We successfully used the Py-GC/MS technique for the analysis of paints by artists Clyfford Still and Jackson Pollock to identify the synthetic organic pigments and the binding media. Graphical AbstractPyrogram of PR49, with fragments produced by pyrolysis

Historical and archaeological textiles: an insight on degradation products of wool and silk yarns.

The characterisation of micro-samples from works of art and archaeological residues is a particularly complex task, due to the fact that only a relatively low amount of material is available for sampling, and compounds both derived from the target analytes and the matrix can be simultaneously present. Thus, sensitive, selective and reliable analytical procedures need to be developed. This paper presents the optimisation of an instrumental procedure based on liquid chromatography with mass spectrometric detection, which allows for determining selected analytes (anthraquinones, tannins, flavonoids), along with their known degradation products: phenolic acids. The instrumental parameters were optimised in terms of selecting the best ionisation source (APCI and ESI were compared), choosing the compound-dependant MS parameters and enhancing selectivity and sensitivity (SIM and MRM analyses were compared). The proposed procedure proved to be sensitive and selective, with limits of detection (0.4-20 ng/mL). The analytical procedure was validated by characterising reference materials, i.e. dyed and undyed woollen and silk yarns, both freshly prepared and artificially aged. Particularly, the study focused on the determination of 4-hydroxybenzoic acid, and on the correlation between its relative amounts with respect to ageing time. The optimised procedure was also applied to historical samples and proved fundamental in unravelling the complex composition of black dyed yarns collected from a medieval tapestry. The much degraded yarns were dyed with a tannin based dye, extracted from gallnuts, alder bark or sumac; the less degraded ones were coloured by superimposing colours with cochineal, madder, weld and indigo dye baths, and eventually by adding gallo-tannins as well.