Alkylresorcinol detection and identification in archaeological pottery using ultra-high-performance liquid chromatography-quadrupole/Orbitrap mass spectrometry.

RATIONALE: Alkylresorcinols (AR) are cereal-specific biomarkers and have recently been found in archaeological pots. However, their low concentrations and high susceptibility to degradation make them difficult to detect using conventional gas chromatography mass spectrometry (GC/MS). Here we describe the development of a more sensitive liquid chromatography mass spectrometry (LC/MS) method to detect these compounds. METHOD: A method based on the use of ultra-high-performance liquid chromatography (UHPLC) coupled to an Orbitrap mass analyser was established and validated for the detection of low-concentration ARs in pottery. During the preliminary experiments, UHPLC-Q/Orbitrap MS (ultra-high-performance liquid chromatography-quadrupole/Orbitrap mass spectrometry) was demonstrated to be more sensitive, and a wide range of AR homologues in cereal extracts were detected, unlike UHPLC-QTOFMS (ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry) and GC/MS. The developed method was utilised to profile AR homologue distribution in modern cereal samples and reanalyse AR-containing pots from the archaeological site of Must Farm. RESULTS: A highly sensitive LC/MS method with a limit of detection (LOD) of 0.02 µg/g and a limit of quantification (LOQ) of 0.06 µg/g was used to profile ARs in five modern cereal grains. The obtained LOD is 250 times lower than that obtained using the conventional GC/MS approach. AR 21:0 was the most abundant homologue in all four Triticum spp.-einkorn, emmer, Khorasan wheat and common wheat. Meanwhile, AR 25:0 was the predominant homologue in barley, potentially enabling differentiation between wheat and barley. The developed LC/MS-based method was successfully used to analyse ARs extracted from Must Farm potsherds and identified the cereal species most likely processed in the pots-emmer wheat. CONCLUSION: The described method offers an alternative and more sensitive approach for detecting and identifying ARs in ancient pottery. It has been successfully utilised to detect AR homologues in archaeological samples and discriminate which cereal species-wheat and barley-were processed in the pots.

The earliest basketry in southern Europe: Hunter-gatherer and farmer plant-based technology in Cueva de los Murciélagos (Albuñol).

Plant material culture can offer unique insights into the ways of life of prehistoric societies; however, its perishable nature has prevented a thorough understanding of its diverse and complex uses. Sites with exceptional preservation of organic materials provide a unique opportunity for further research. The burial site of Cueva de los Murciélagos in southern Iberia, uncovered during 19th-century mining activities, contained the best-preserved hunter-gatherer basketry in southern Europe, together with other unique organic artifacts associated with the first farming communities, such as sandals and a wooden hammer. We present 14 14C dates for the perishable artifacts (N = 76), situating the assemblage between the Early and Middle Holocene (c. 7500 to 4200 cal BCE). Our integrated analysis includes raw material determination and technological and chrono-cultural contextualization of this unique and important set of materials.

Lipid residues in pottery from the Indus Civilisation in northwest India.

This paper presents novel insights into the archaeology of food in ancient South Asia by using lipid residue analysis to investigate what kinds of foodstuffs were used in ceramic vessels by populations of the Indus Civilisation in northwest India. It examines how vessels were used in urban and rural Indus settlements during the Mature Harappan period (c.2600/2500-1900 BC), the relationship between vessels and the products within them, and identifies whether changes in vessel use occurred from the Mature Harappan to Late Harappan periods, particularly during climatic instability after 4.2 ka BP (c.2100 BC). Despite low lipid concentrations, which highlight challenges with conducting residue analysis in arid, seasonally-wet and alkaline environments, 71% of the vessels yielded appreciable quantities of lipid. Lipid profiles revealed the use of animal fats in vessels, and contradictory to faunal evidence, a dominance of non-ruminant fats, with limited evidence of dairy processing. The absence of local modern reference fats makes this dataset challenging to interpret, and it is possible that plant products or mixtures of plant and animal products have led to ambiguous fatty acid-specific isotopic values. At the same time, it appears that urban and rural populations processed similar types of products in vessels, with limited evidence for change in vessel use from the urban to the post-urban period. This study is a systematic investigation into pot lipid residues from multiple sites, demonstrating the potential of the method for examining ancient Indus foodways and the need for the development of further research in ancient organic residues in South Asia.

Latitudinal gradient in dairy production with the introduction of farming in Atlantic Europe.

The introduction of farming had far-reaching impacts on health, social structure and demography. Although the spread of domesticated plants and animals has been extensively tracked, it is unclear how these nascent economies developed within different environmental and cultural settings. Using molecular and isotopic analysis of lipids from pottery, here we investigate the foods prepared by the earliest farming communities of the European Atlantic seaboard. Surprisingly, we find an absence of aquatic foods, including in ceramics from coastal sites, except in the Western Baltic where this tradition continued from indigenous ceramic using hunter-gatherer-fishers. The frequency of dairy products in pottery increased as farming was progressively introduced along a northerly latitudinal gradient. This finding implies that early farming communities needed time to adapt their economic practices before expanding into more northerly areas. Latitudinal differences in the scale of dairy production might also have influenced the evolution of adult lactase persistence across Europe.

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.