Richard P. Evershed

Molecularly-uncharacterized organic matter comprises most reduced carbon in soils, sediments and natural waters. The origins, reactions and fates of these ubiquitous materials are relatively obscure, in large part because the rich vein of geochemical information that typically derives from detailed structural and stereochemical analysis is yet to be tapped. This discussion highlights current knowledge about the origins and characteristics of molecularly uncharacterized organic matter in the environment and outlines possible means by which this structurally uncharted frontier might best be explored.

Horse domestication revolutionized transport, communications, and warfare in prehistory, yet the identification of early domestication processes has been problematic. Here, we present three independent lines of evidence demonstrating domestication in the Eneolithic Botai Culture of Kazakhstan, dating to about 3500 B.C.E. Metrical analysis of horse metacarpals shows that Botai horses resemble Bronze Age domestic horses rather than Paleolithic wild horses from the same region. Pathological characteristics indicate that some Botai horses were bridled, perhaps ridden. Organic residue analysis, using delta13C and deltaD values of fatty acids, reveals processing of mare's milk and carcass products in ceramics, indicating a developed domestic economy encompassing secondary products.

Organic residue analysis utilizes analytical organic chemical techniques to identify the nature and origins of organic remains that cannot be characterized using traditional techniques of archaeological investigation (because they are either amorphous or invisible). The field is founded upon the principle that the biomolecular, or biochemical, components of organic materials associated with human activity survive in a wide variety of locations and deposits at archaeological sites. The archaeological information contained in organic residues is represented by the biomolecular components of the natural products that contribute to the formation of a given residue. By applying appropriate separation (chromatographic) and identification (mass spectrometric) techniques, the preserved, and altered, biomolecular components of such residues can be revealed. Once identified, the Archaeological Biomarker Concept can be applied, wherein the structure and even isotopic composition(s) of a given biomolecule or suite of biomolecules (the ‘chemical fingerprint’) can be related to the compositions of organisms exploited by humans in the past. As the organic residue field emerges from its pre‐paradigmatic phase, and the organic residue revolution gathers pace, the way is open for challenging many long‐held archaeological hypotheses and offering new perspectives on the study of human activity in the past.

DNA from excrements can be amplified by means of the polymerase chain reaction. However, this has not been possible with ancient feces. Cross-links between reducing sugars and amino groups were shown to exist in a Pleistocene coprolite from Gypsum Cave, Nevada. A chemical agent, N-phenacylthiazolium bromide, that cleaves such cross-links made it possible to amplify DNA sequences. Analyses of these DNA sequences showed that the coprolite is derived from an extinct sloth, presumably the Shasta ground sloth Nothrotheriops shastensis. Plant DNA sequences from seven groups of plants were identified in the coprolite. The plant assemblage that formed part of the sloth's diet exists today at elevations about 800 meters higher than the cave.

The spread of farming from western Asia to Europe had profound long-term social and ecological impacts, but identification of the specific nature of Neolithic land management practices and the dietary contribution of early crops has been problematic. Here, we present previously undescribed stable isotope determinations of charred cereals and pulses from 13 Neolithic sites across Europe (dating ca. 5900-2400 cal B.C.), which show that early farmers used livestock manure and water management to enhance crop yields. Intensive manuring inextricably linked plant cultivation and animal herding and contributed to the remarkable resilience of these combined practices across diverse climatic zones. Critically, our findings suggest that commonly applied paleodietary interpretations of human and herbivore δ(15)N values have systematically underestimated the contribution of crop-derived protein to early farmer diets.

Domesticated animals formed an important element of farming practices in prehistoric Britain, a fact revealed through the quantity and variety of animal bone typically found at archaeological sites. However, it is not known whether the ruminant animals were raised purely for their tissues (e.g., meat) or alternatively were exploited principally for their milk. Absorbed organic residues from pottery from 14 British prehistoric sites were investigated for evidence of the processing of dairy products. Our ability to detect dairy fats rests on the observation that the delta(13)C values of the C(18:0) fatty acids in ruminant dairy fats are approximately 2.3 per thousand lower than in ruminant adipose fats. This difference can be ascribed to (i) the inability of the mammary gland to biosynthesize C(18:0); (ii) the biohydrogenation of dietary unsaturated fatty acids in the rumen; and (iii) differences (i.e., 8.1 per thousand ) in the delta(13)C values of the plant dietary fatty acids and carbohydrates. The lipids from a total of 958 archaeological pottery vessels were extracted, and the compound-specific delta(13)C values of preserved fatty acids (C(16:0) and C(18:0)) were determined via gas chromatography-combustion-isotope ratio mass spectrometry. The results provide direct evidence for the exploitation of domesticated ruminant animals for dairy products at all Neolithic, Bronze Age, and Iron Age settlements in Britain. Most significantly, studies of pottery from a range of key early Neolithic sites confirmed that dairying was a widespread activity in this period and therefore probably well developed when farming was introduced into Britain in the fifth millennium B.C.

Abstract Pigs were raised on six isotopically controlled diets to examine the dietary macronutrients used in the synthesis of bulk bone biochemical components (apatite, collagen and lipids) and individual compounds (bone fatty acids, cholesterol and amino acids from collagen). δ 13 C values of apatite and bulk bone lipids reflected those of the whole diet, with Δ 13 C apatite‐wholediet = 10.2 ± 1.3‰ and Δ 13 C bonelipids‐wholediet = −2.4 ± 0.7‰. A wide variation observed in the Δ 13 C collagen‐wholediet values (0.5 to 6.1‰) was hypothesized to reflect the relative importance of (i) the direct incorporation of essential amino acids, and (ii) the balance between direct incorporation and de novo synthesis of non‐essential amino acids. Linear regression (n = 6) was used to assess the relationship between the δ 13 C values of whole diet and bulk bone components and individual compounds. Whole diet δ 13 C values showed a strong correlation with those of bone cholesterol (R 2 = 0.81) and non‐essential fatty acids (0.97 ≤ R 2 ≤ 0.99). Not surprisingly, bone linoleic acid δ 13 C values correlated well with dietary linoleic acid (R 2 = 0.95). Mass balance calculations using the δ 13 C values of single amino acids accurately predicted the δ 13 C value of whole collagen. The δ 13 C values of whole diet were well correlated with those of the non‐essential amino acids, alanine (R 2 = 0.85) and glutamate (R 2 = 0.96) in collagen. The essential amino acids leucine (Δ 13 C collagenleu‐dietleu = 0.5 ± 1.2‰) and phenylalanine (Δ 13 C collagenphe‐dietphe = −0.6 ± 0.6‰) showed little isotopic fractionation between diet and bone collagen. Copyright © 2003 John Wiley & Sons, Ltd.

One of the defining characteristics of a biomarker is the retention, during diagenesis, of structural characteristics indicative of its original biogenic source (Peters and Moldowan, 1993). Since the 1960s an increasing interest has developed in the use of environmental biomarker compounds to monitor levels of human and animal waste introduced to marine and terrestrial environments; the relative stability of these compounds enabling both spatial and long-term temporal studies to be realized (e.g., Walker et al., 1982; Vivian, 1986; Evershed and Bethell, 1996 and references therein). The specificity of particular biomarkers for different faecal sources makes their use particularly attractive especially in circumstances where deducing the origin of sewage constituting a pollution event is crucial. Research into organicmatter in the marine and terrestrial environments over the last 20 years has led to the development of two main groups of organic compounds found in faecal matter that can be used to monitor sewage, namely: 5b-stanols and bile acids. This communication provides an overview for researchers not necessarily familiar with molecular methods of sewage monitoring. The two compound classes will be considered separately, and then their integration and future development discussed.

Rats were raised on a variety of isotopically controlled diets comprising 20% C3, C4 or marine protein and C3 and/or C4 non-protein or energy (i.e. sucrose, starch and oil) macronutrients. Compound specific stable carbon isotope (δ13C) analysis was performed on the cholesterol isolated from the diet (n=7 ) and bone (n=15 ) of these animals and the values compared with bulk δ13C measurements of bone collagen and apatite. The dietary signals reflected by these three bone biochemical components were investigated using linear regression analysis. δ13C values of bone cholesterol were shown to reflect whole diet δ13C values, collagen to reflect mainly dietary protein values and apatite to reflect whole diet values. Further correlations between dietary protein-to-energy spacings (Δ13Cprot-engy = δ13Cprotein – δ13Cenergy) and whole diet-to-bone component fractionations (Δ13Cbcomp-wdiet = δ13Cbone component – δ13Cwhole diet) indicates that for hypothetical diets where protein δ13C values are equal to energy values, fractionations between whole diet and bone biochemical fractions are –3.3‰ for cholesterol, +5.4‰ for collagen and +9.5‰ for apatite. Moreover, the narrow range of variation observed in apatite-to-cholesterol spacings (Δ13Capat-bchol) suggests that cholesterol δ13C values can potentially also be used as an independent test for the isotopic integrity of apatite δ13C values. These insights into bone cholesterol, collagen and apatite dietary signals, diet-to-bone fractionations and bone component-to-bone component spacings provide the basis for more accurate interpretations of the dietary behaviour of archaeological populations and food webs when the δ13C analysis of bone is employed.

Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (−8 to 27 °C) and pH (3–8) range and present the first peat-specific brGDGT-based temperature and pH calibrations. Our results demonstrate that the degree of cyclisation of brGDGTs in peat is positively correlated with pH, pH = 2.49 × CBTpeat + 8.07 (n = 51, R2 = 0.58, RMSE = 0.8) and the degree of methylation of brGDGTs is positively correlated with MAAT, MAATpeat (°C) = 52.18 × MBT5me′ − 23.05 (n = 96, R2 = 0.76, RMSE = 4.7 °C). These peat-specific calibrations are distinct from the available mineral soil calibrations. In light of the error in the temperature calibration (∼4.7 °C), we urge caution in any application to reconstruct late Holocene climate variability, where the climatic signals are relatively small, and the duration of excursions could be brief. Instead, these proxies are well-suited to reconstruct large amplitude, longer-term shifts in climate such as deglacial transitions. Indeed, when applied to a peat deposit spanning the late glacial period (∼15.2 kyr), we demonstrate that MAATpeat yields absolute temperatures and relative temperature changes that are consistent with those from other proxies. In addition, the application of MAATpeat to fossil peat (i.e. lignites) has the potential to reconstruct terrestrial climate during the Cenozoic. We conclude that there is clear potential to use brGDGTs in peats and lignites to reconstruct past terrestrial climate.

Research Article| August 01, 2013 Concordant monsoon-driven postglacial hydrological changes in peat and stalagmite records and their impacts on prehistoric cultures in central China Shucheng Xie; Shucheng Xie 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Richard P. Evershed; Richard P. Evershed 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK Search for other works by this author on: GSW Google Scholar Xianyu Huang; Xianyu Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Zongmin Zhu; Zongmin Zhu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Richard D. Pancost; Richard D. Pancost 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK Search for other works by this author on: GSW Google Scholar Philip A. Meyers; Philip A. Meyers 4Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, 48109-1005, USA Search for other works by this author on: GSW Google Scholar Linfeng Gong; Linfeng Gong 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Chaoyong Hu; Chaoyong Hu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Junhua Huang; Junhua Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Shihong Zhang; Shihong Zhang 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Yansheng Gu; Yansheng Gu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Junying Zhu Junying Zhu 5Hubei Provincial Institute of Archaeology, Wuhan 430077, China Search for other works by this author on: GSW Google Scholar Author and Article Information Shucheng Xie 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Richard P. Evershed 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK Xianyu Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Zongmin Zhu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Richard D. Pancost 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK Philip A. Meyers 4Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, 48109-1005, USA Linfeng Gong 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Chaoyong Hu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Junhua Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Shihong Zhang 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Yansheng Gu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Junying Zhu 5Hubei Provincial Institute of Archaeology, Wuhan 430077, China Publisher: Geological Society of America Received: 15 Dec 2012 Revision Received: 05 Mar 2013 Accepted: 06 Mar 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2013 Geological Society of America Geology (2013) 41 (8): 827–830. https://doi.org/10.1130/G34318.1 Article history Received: 15 Dec 2012 Revision Received: 05 Mar 2013 Accepted: 06 Mar 2013 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Shucheng Xie, Richard P. Evershed, Xianyu Huang, Zongmin Zhu, Richard D. Pancost, Philip A. Meyers, Linfeng Gong, Chaoyong Hu, Junhua Huang, Shihong Zhang, Yansheng Gu, Junying Zhu; Concordant monsoon-driven postglacial hydrological changes in peat and stalagmite records and their impacts on prehistoric cultures in central China. Geology 2013;; 41 (8): 827–830. doi: https://doi.org/10.1130/G34318.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Asian monsoon records are widely documented, but specific proxies of monsoonal rainfall are limited. We present here two new independent proxy records from peatland and stalagmite archives that indicate a high degree of concordance between monsoon-driven hydrological changes occurring since the last deglaciation in a broad region of central China. The wet periods elevated the water table in the Dajiuhu peatland, as recorded by reduced mass accumulation rates of hopanoids, biomarkers for aerobic microbes, confirmed by molecular phylogenic analyses. The hopanoid-based reconstruction is supported by the first report of the environmental magnetism parameter ARM/SIRM (anhysteretic remanent magnetization / saturation isothermal remanent magnetization; ratio of fine magnetic particles to total ferrimagnetic particles) in a stalagmite from Heshang Cave in central China. Heavy rainfall resulted in the enhanced transport of coarse particles to the cave and thus low ARM/SIRM values in the stalagmite. The hydrological conditions inferred from the two records reveal three relatively long wet periods in central China: 13–11.5 k.y. ago, 9.5–7.0 k.y. ago, and 3.0–1.5 k.y. ago. Archaeological evidence for the hydrological impacts on regional populations comes from the observation that temporal shifts among six distinctive cultures of the Neolithic Period to the Iron Age in central China occurred during wet periods or flood episodes. Spatiotemporal distributions of >1600 prehistoric settlement sites correlate with the proxy-inferred fluctuating hydrological conditions, with enhanced flooding risk forcing major relocations of human settlements away from riparian zones. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Despite the significant achievements of organic residues analysis of archaeological pottery, the sometimes low lipid recovery and the need to process increasingly large collections of sherds to tackle important archaeological questions require the development of a more efficient and rapid extraction method. In this paper we present a novel methodology for the extraction of absorbed organic residues directly from crushed archaeological ceramic using acidified methanol (H2SO4–MeOH 2% v/v, 70 °C, 1 h). This new protocol was tested by: (i) verifying the recovery of organic residues from previously studied archaeological vessels from different geographical regions, exhibiting a range of different lipid distributions often found in archaeological pottery, and (ii) demonstrating enhanced recovery of organic residues from potsherds that did not yield appreciable lipids when using the widely applied chloroform–methanol extraction. The application of the direct acidified methanol extraction recovers higher concentrations of lipid residues together with simultaneous production of methyl esters of fatty acids, allowing extraction and methylation to be completed in 20% of the time compared to conventional solvent extraction and derivatisation for gas chromatography (GC), gas chromatography mass spectrometry (GC-MS) and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS).

The bacterial membrane lipid-based continental paleothermometer, the MBT/CBT or MBT′–CBT proxy (methylation index of branched tetraethers/cyclization of branched tetraethers), results in a large temperature deviation when applied in semiarid and arid regions. Here we propose new calibration models based on the investigation of >100 surface soils across a large climatic gradient, with a particular focus on semiarid and arid regions of China, and apply them to a loess–paleosol sequence. As reported elsewhere, MBT values exhibit a much higher correlation with MAAT than with summer temperature, suggesting a minimal seasonality bias; however, MBT is apparently insensitive to temperature <5 °C or >20 °C. Additional complexities are apparent in alkaline and arid soils, which are characterized by different relationships to climatic parameters than those in the complete Chinese (or global) dataset. For example, MBT and CBT indices exhibit a negative correlation in alkaline and arid soils, in contrast to their positive correlation in acid soils. Moreover, the cyclization ratio of bGDGTs (CBT), previously defined as a proxy for soil pH, is apparently primarily controlled by MAAT in these alkaline soils. Thus, we propose (1) a local Chinese calibration of the MBT–CBT proxy and (2) an alternative temperature proxy for use in semiarid and arid regions based on the fractional abundances of bGDGTs; the latter has a markedly higher determination factor and lower root mean square error in alkaline soils than the Chinese local calibration and is suggested to be preferred for paleotemperature reconstruction in Chinese loess/paleosol sequences. These new bGDGT proxies have been applied to the Weinan Holocene paleosol section of the Chinese Loess Plateau (CLP). The fractional abundance calibration, when applied in the Weinan Holocene paleosol, produces a total Holocene temperature variation of 5.2 °C and a temperature for the topmost sample that is consistent with the modern temperature. Previously, we showed that the ratio of archaeal isoprenoid GDGTs to bGDGTs (Ri/b) increases at MAP < 600 mm, and elevated Ri/b values (>0.5) in the CLP suggest the presence of enhanced aridity in the late Holocene in North China. In combination, the high Ri/b ratios (>0.5) and the associated low MBT values (<0.4) reveal the co-occurrence of dry and cold events, especially in the latest Holocene, in the loess–paleosol sequences in CLP, and probably also in cold and arid regions outside of CLP.

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.

In European and many African, Middle Eastern and southern Asian populations, lactase persistence (LP) is the most strongly selected monogenic trait to have evolved over the past 10,000 years1. Although the selection of LP and the consumption of prehistoric milk must be linked, considerable uncertainty remains concerning their spatiotemporal configuration and specific interactions2,3. Here we provide detailed distributions of milk exploitation across Europe over the past 9,000 years using around 7,000 pottery fat residues from more than 550 archaeological sites. European milk use was widespread from the Neolithic period onwards but varied spatially and temporally in intensity. Notably, LP selection varying with levels of prehistoric milk exploitation is no better at explaining LP allele frequency trajectories than uniform selection since the Neolithic period. In the UK Biobank4,5 cohort of 500,000 contemporary Europeans, LP genotype was only weakly associated with milk consumption and did not show consistent associations with improved fitness or health indicators. This suggests that other reasons for the beneficial effects of LP should be considered for its rapid frequency increase. We propose that lactase non-persistent individuals consumed milk when it became available but, under conditions of famine and/or increased pathogen exposure, this was disadvantageous, driving LP selection in prehistoric Europe. Comparison of model likelihoods indicates that population fluctuations, settlement density and wild animal exploitation—proxies for these drivers—provide better explanations of LP selection than the extent of milk exploitation. These findings offer new perspectives on prehistoric milk exploitation and LP evolution. Examination of archaeological pottery residues and modern genes suggest that environmental conditions, subsistence economics and pathogen exposure may explain selection for lactase persistence better than prehistoric consumption of milk.

The stable carbon isotope (δ 13 C) compositions of individual fatty acid components of remnant fats preserved in archaeological pottery vessels show that dairying was a component of archaeological economies. Characteristic δ 13 C values arise from biases in the biosynthetic origins of the C 18:0 fatty acids in milk and adipose fat. Milk and adipose fat from animals raised on similar pastures and fodders have distinct isotopic signatures.

Organic residues are extracted from materials of archaeological interest by solvent extraction and subjected directly to high-temperature gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The use of high-temperature GC allows intact acyl lipids, e.g., triacylglycerols, diacylglycerols, monoacylglycerols and wax esters, to be analysed without prior degradation (e.g., saponification) to release constituent fatty acids and alcohols. Trimethylsilylation is employed to block protic sites in free fatty acids and hydroxylated components. The data obtained from temperature programmed GC and GC-MS analyses, employing immobilised apolar (dimethyl polysiloxane type) stationary phases, provide essential compositional information that would be lost if the more conventional degradative approach to acyl lipid analysis was adopted.

Lipid analysis of modern bog vegetation revealed n-alkane distributions for Sphagnum species displaying enhanced abundances of lower chain length homologues (C21–C25). Other plants examined revealed typical higher plant distributions (C29 or C31 maxima). Investigation of a 40 cm peat profile from Bolton Fell Moss, Cumbria, UK showed a varying abundance of the n-C23 homologue down core which appear to be related to vegetation changes, which are presumed to occur as a result of climate variation.

Animal fats are preserved at archaeological sites in association with unglazed pottery, human and animal remains, and other deposits or hoards. High-temperature gas chromatography (HT-GC) and combined HT-GC/mass spectrometry (HT-GC/MS) has confirmed the presence of animal fats in lipid extracts of artifacts. Degradation products and pathways have been discerned through the analyses of archaeological finds and the products of laboratory and field-based decay experiments. The origins of preserved fats have been determined through detailed compositional analysis of their component fatty acids by GC, by GC/MS of dimethyl disulfide derivatives of monoenoic components, and by GC−combustion−isotope ratio-MS (GC−C−IRMS), to derive diagenetically robust δ13C values. Regiospecific analysis of intact triacylglycerols by high-performance liquid chromatography/MS (HPLC/MS), with atmospheric pressure chemical ionization, provides a further criterion for establishing the origin of fats. Preparative GC has been employed to isolate individual fatty acids from archaeological pottery in sufficient amounts for 14C dating.

Lipid extracts from four long-term experiments (Broadbalk Wilderness, Geescroft Wilderness, Hoosfield Spring Barley and Park Grass) were analysed using a combination of gas chromatography, gas chromatography–mass spectrometry and gas chromatography–combustion–isotope ratio mass spectrometry. The lipid content of the primary organic inputs for each soil were also analysed in order to assess the early diagenetic fate of the various compound classes present. Soil pH was observed to, either directly or indirectly, have a significant effect on lipids with a relative increase in abundance of n-alkanes at higher pH (7.31) and a large relative increase in n-alkanoic and ω-hydroxy acids at low pH (3.74). Triacylglycerols exhibited severe losses irrespective of pH. In an arable soil, n-alkanoic acids showed a temporal decrease in concentration whilst levels of n-alkanols remained static, the difference was ascribed to a more rapid turnover and possible leachate migration of the n-alkanoic acids. The phytosterol, sitosterol, was observed to rapidly diminish in soils possibly as a result of assimilation by soil dwelling invertebrates. Analysis of 5β-stigmastanol (a faecal biomarker) showed that it remained at levels indicative of manuring even after 113 years. Furthermore, analysis of 5β-stanyl esters revealed a manuring signal even more persistent than that exhibited by the free stanols. Knowledge of the biogeochemical cycling of lipids in the soil environment will help facilitate understanding of the processes which underpin carbon cycling in soils.

The diets of laboratory rats were isotopically and nutritionally manipulated using purified C3 and/or C4 macronutrients to investigate the routing of dietary carbon to bone collagen biosynthesis. Diets were formulated with purified proteins, carbohydrates and lipids of defined composition and natural abundance stable isotope ratios. Bulk protein and constituent amino acid delta(13)C values determined for whole diet and bone collagen provided the basis for assessing isotopic fractionation and estimating the degree of routing versus synthesis de novo of essential, non-essential and conditionally indispensable amino acids. Essential and conditionally indispensable amino acids were shown to be routed from diet to collagen with little isotopic fractionation whereas non-essential amino acids differed by up to 20 per thousand. Mathematical modelling of the relationships between macronutrient and tissue delta(13)C values provided qualitative and quantitative insights into the metabolic and energetic controls on bone collagen biosynthesis. Essential amino acids comprise 21.7 % of the carbon in collagen, defining the minimum amount of dietary carbon routing. Estimates of 42 and 28 % routing were shown for the non-essential amino acids, glycine and aspartate, respectively. In total, the routing of non-essential and conditionally indispensable amino acids was estimated to equal 29.6 % of the carbon in collagen. When the contribution of carbon from the essential amino acids is also considered, we arrive at an overall minimum estimate of 51.3 % routing of dietary amino acid carbon into bone collagen.

ω-(o-Alkylphenyl)alkanoic acids with 16, 18 and 20 carbon atoms were identified in archaeological pottery vessels from coastal sites in Southern Brazil. Such compounds are presumed to form during heating of triunsaturated fatty acids (C16:3, C18:3 and C20:3), which are commonly found in the tissues of marine animals. The detection of these unusual cyclic compounds together with the isoprenoid fatty acids, 4,8,12-trimethyltetradecanoic acid and phytanic acid and substantial quantities of archaeological bones of fish and mollusca, provides evidence for the processing of marine animal products in archaeological pottery.

A 40 cm deep Sphagnum-dominated peat monolith from Bolton Fell Moss in Northern England was systematically investigated by lipid molecular stratigraphy and compound-specific δ13C and δD analysis using gas chromatography (GC), GC-mass spectrometry (GC-MS), GC-combustion-isotope ratio-MS (GC-C-IRMS) and GC-thermal conversion-IRMS (GC-TC-IRMS) techniques. 210Pb dating showed the monolith accumulated during the last ca. 220 yr, a period encompassing the second part of Little Ice Age. While the distributions of lipids, including n-alkan-1-ols, n-alkan-2-ones, wax esters, sterols, n-alkanoic acids, α,ω-alkandioic acids and ω-hydroxy acids, display relatively minor changes with depth, the cooler climate event was recorded in the concentrations of n-alkanes and organic carbon, CPI values of n-alkanes and n-alkanoic acids, and the ratio of 5-n-alkylresorcinols/sterols. Superimposed on the fossil fuel effect, the relatively cooler climate event was also recorded by δ13C values of individual hydrocarbons, especially the C23 n-alkane, a major compound in certain Sphagnum spp. The δD values of the C29 and C33 n-alkanes correlated mainly with plant composition and were relatively insensitive to climatic change. In contrast the C23 n-alkane displayed variation that correlated strongly with recorded temperature for the period represented by the monolith, agreeing with previously reported deuterium records in tree ring cellulose spanning the same period in Scotland, Germany and the USA, with more negative values occurring during the second part of Little Ice Age. These biomarker characteristics, including the compound-specific δ13C and δD records, provide a new set of proxies of climatic change, potentially independent of preserved macrofossils which will be of value in deeper sections of the bog where the documentary records of climate are unavailable and humification is well advanced.

A new method is described for distinguishing between animal fats preserved in ancient pottery. Analysis of lipid fractions from two morphologically distinct vessel types (lamps and “dripping dishes”) using on-line gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS) showed that they could be distinguished by plotting the δ13C value for n-hexadecanoic acid against that for n-octadecanoic acid. The δ13C values obtained for modern reference fats from domesticated animals likely to have been important in antiquity showed the lamp extracts to correlate with ruminant animal fat, such as sheep or cattle, whereas the “dripping dishes” had δ13C values similar to those of non-ruminant animal fat, such as pig. These findings were entirely consistent with distributional information obtained by GC and with positional isomer information gained from analysis of dimethyldisulphide derivatives of the monounsaturated fatty acids. The results indicate that GC–C–IRMS has considerable potential for the classification of animal fats absorbed in ancient pottery particularly where fatty acid distributions have been altered by degradation during vessel use or burial. δ13C values were also shown to be of value in detecting the use of vessels in the processing of animal products from more than one source.

High performance liquid chromatography in conjunction with atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI-MS) enables the positional isomers of individual triacylglycerols in mixtures to be identified. Application of HPLC/APCI-MS to the analysis of soybean oil allowed thirty nine triacylglycerols and seven diacylglycerols to be positively identified. The compounds present were quantified and the distribution of fatty acids in the β-position calculated. This distribution compared favourably with that obtained using a more conventional regiospecific lipase degradation of the oil. A survey of the acylglycerol components of a range of vegetable oils (blackcurrant, blue poppy seed, evening primrose, extra virgin olive, hazelnut, maize and rapeseed) carried out using HPLC/APCI-MS is reported. ©1997 John Wiley & Sons, Ltd.

Organic residue analysis has been performed on 62 reconstructed vessels from a single archaeological site (Rounds, Northamptonshire, U.K.). In order to establish regions of lipid accumulation within a vessel, sherds were sampled from different parts of a vessel, for example base, body and rim, and submitted to lipid extraction procedures. The techniques of high‐temperature gas chromatography (GC) and GC/mass spectrometry (GC/MS) were then used to analyse the sherd lipid extracts. The quantitative results obtained show differential accumulation and preservation of lipid in various parts of the same vessel. This latter observation has serious implications for the sampling of potsherds for organic residue analysis. Furthermore, the amount of absorbed lipid varies quite considerably between vessel types. On this basis, a new method is proposed for classifying vessel use by comparing the concentration of lipid present in different parts of individual vessels.

Studies performed during the last two decades have shown that lipids are preserved in association with a wide range of artefacts and ecofacts recovered from archaeological sites, e.g. pottery vessels and skeletal remains. The majority of work in this area has focused on the use of molecular structures (‘biomarkers’) and distributions (‘fingerprints’) to assess the nature and origin of commodities associated with past cultural, economic and agricultural practices. However, since lipids, like all other classes of biomolecule, are affected by degradation (both pre– and post–burial), emphasis is now being placed on the complementary use of diagenetically robust, compound–specific stable isotope measurements to enhance the scope and reliability of archaeological interpretations. A feature of the δ 13 C values of individual lipids, rather than bulk measurements of biochemically more heterogeneous materials, lies in their capacity to reflect differences in both the isotopic composition of the carbon sources used in their biosynthesis and the routing of dietary lipids and their metabolites in consumer organisms. This isotopic information, accessible by gas chromatography–combustion–isotope ratio mass spectrometry, has opened up new avenues of investigation concerning human activity in prehistory.

Abstract All scientific investigations require experimentation to test hypotheses and support interpretations. Thus, experimental studies are an indispensable aspect of investigations of organic residues from archaeological ceramics. Experimental methods have been applied to provide insights into factors relating to vessels use and burial. Studies relating to vessel use have used replica vessels, ceramic chips and powder to investigate both physical and chemical phenomena relating to organic residue deposition and transformations. Ethnographic vessels are employed to bridge a practical gap, providing insights into the impacts of long-term vessel use that would be impossible to address in laboratory experiments. By combining such studies we have provided important insights into the chemical compositions observed and prompted searches for novel marker compounds that might otherwise have been overlooked. Potsherds impregnated with organic residues provide substrates for investigating the impacts of burial on chemical and stable isotopic compositions.

Caffeine, a widely consumed adenosine A(1) and A(2A) receptor antagonist, is valued as a psychostimulant, but it is also anxiogenic. An association between a variant within the ADORA2A gene (rs5751876) and caffeine-induced anxiety has been reported for individuals who habitually consume little caffeine. This study investigated whether this single nucleotide polymorphism (SNP) might also affect habitual caffeine intake, and whether habitual intake might moderate the anxiogenic effect of caffeine. Participants were 162 non-/low (NL) and 217 medium/high (MH) caffeine consumers. In a randomized, double-blind, parallel groups design they rated anxiety, alertness, and headache before and after 100 mg caffeine and again after another 150 mg caffeine given 90 min later, or after placebo on both occasions. Caffeine intake was prohibited for 16 h before the first dose of caffeine/placebo. Results showed greater susceptibility to caffeine-induced anxiety, but not lower habitual caffeine intake (indeed coffee intake was higher), in the rs5751876 TT genotype group, and a reduced anxiety response in MH vs NL participants irrespective of genotype. Apart from the almost completely linked ADORA2A SNP rs3761422, no other of eight ADORA2A and seven ADORA1 SNPs studied were found to be clearly associated with effects of caffeine on anxiety, alertness, or headache. Placebo administration in MH participants decreased alertness and increased headache. Caffeine did not increase alertness in NL participants. With frequent consumption, substantial tolerance develops to the anxiogenic effect of caffeine, even in genetically susceptible individuals, but no net benefit for alertness is gained, as caffeine abstinence reduces alertness and consumption merely returns it to baseline.

Chitin is present in fossil insects from the Oligocene (24.7 million years ago) lacustrine shales of Enspel, Germany. This result, which was obtained by analytical pyrolysis, extends by nearly 25 million years the length of time that chemically detectable remains of this biomolecule are known to survive. The embedding sediment is dominated by diatoms, which reflect high productivity in the paleolake. The primary control on the preservation of chitin is thus not time; it may persist in older sediments where suitable paleoenvironmental conditions prevailed.

Total lipid extracts and solvent insoluble organic matter in soils from the Park Grass Experiment at Rothamsted Experimental Station, Harpenden, U.K. were studied to determine the effect of pH on the preservation/degradation of plant derived biomolecules. Analyses involved high temperature-gas chromatography (HT-GC), HT-GC–mass spectrometry (HT-GC–MS), GC combustion–isotope ratio MS (GCC–IRMS) and flash pyrolysis–GC (Py–GC) and Py–GC–MS. The plots selected for study have pH values ranging from 3.7 to 7.3, with acidic soils exhibiting two distinct horizons (i.e. humic rich top layer and mineral soil). The total lipid extracts of the soil samples with low pH exhibited higher relative abundances of long-chain (>C20) organic acids believed to be derived largely from oxidation of plant lipids. The vegetation signature in the low molecular weight fraction is only retained in the humic rich top layer. The signal in the mineral layer is believed to derive primarily from previous vegetation. Compound specific stable carbon isotope (δ13C) measurements of long-chain n-alkanols are considered to reflect differences in the rate of incorporation of plant lipids into the humic top layer related to the grass species dominating the standing vegetation. In the soil samples of low pH, lignin contributes to the high molecular weight fraction of the humic layer. In contrast, the mineral layer of the same soil shows little evidence of intact lignin, but is instead dominated by amino acid pyrolysis products, probably deriving from (degraded) polypeptides. The pyrolysates of the mineral soils of high pH yield a distribution of products similar to that found in the deeper layer of the low pH samples but with evidence of lignin derived moieties. Overall, soil pH was found to have a significant effect on the preservation of higher plant derived biomolecules including ligno-cellulose.

Man's use of illuminants in lamps or as torches to extend the working day and range of environments accessible to him would have been a major technological advance in human civilisation. The most obvious evidence for this in the archaeological record comes from pottery and stone vessels showing sooting due to the use of a wick in conjunction with a lipid-based fuel or illuminant. A wide range of potential fuels would have been exploited depending upon availability and burning requirements. Reported herein are the results of chemical investigations of a number of lamps recovered from excavations of the site of Qasr Ibrim, Egypt. Gas chromatographic, mass spectrometric and stable carbon isotopic analyses of both free (solvent extractable) and 'bound'(released from solvent extracted pottery by base treatment) lipids have revealed a wide range of saturated fatty acids, hydroxy fatty acids and alpha, omega-dicarboxylic acids. Examination of the distributions of compounds and comparisons with the fatty acid compositions of modern plant oils have allowed a range of fats and oils to be recognised. Specific illuminants identified include Brassicaceae (Cruciferae) seed oil (most likely radish oil, Raphanus sativus), castor oil (from Ricinus communis), animal fat, with less diagnostic distributions and delta(13)C values being consistent with low stearic acid plant oils, such as linseed (Linum usitatissimum) or sesame (Sesamum indicum) oils. The identifications of the various oils and fats are supported by parallel investigations of illuminant residues produced by burning various oils in replica pottery lamps. The findings are entirely consistent with the classical writers including Strabo, Pliny and Theophrastrus.

What was burned in lamps in the prehistoric Mediterranean? Olive oil, as one would first suppose? Analysis of absorbed lipids preserved in the fabric of lamps and conical cups from the Minoan site of Mochlos in eastern Crete shows for the first time that beeswax was used as an illuminant.

A range of spectroscopic, ‘wet’ chemical, gas chromatographic (GC) and mass spectrometric (MS) techniques was applied to the characterisation of three soil organic matter (SOM) fractions that have been proposed as the basis of a new SOM turnover model based on measurable, physically defined fractions. The fractions were: the free light fraction (obtained by density separation in NaI solution at a density of 1.80 g cm−3, without disruption of aggregates), the intra-aggregate light fraction (obtained using a second density separation after disrupting aggregates using ultrasonic dispersion) and the organomineral fraction corresponding to the residual heavy material. The techniques employed to investigate the composition of the organic constituents of each fraction were: 13C nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) to study bulk composition. Lipid, lignin and carbohydrate fractions were assessed using GC and GC/MS with appropriate derivatisation, following oxidative and hydrolytic treatments, respectively, in the case of the latter two classes. Proteinaceous components were determined as amino acids using reversed-phase high performance liquid chromatography (HPLC) following 6 M HCl treatment and derivatisation. Each technique revealed marked differences in chemical composition between the organomineral and the two light fractions, with the results being consistent with the organomineral fraction having different biological sources or having undergone a greater degree of degradation or transformation. Several techniques detected differences between the composition of the free light fraction and the intra-aggregate light fraction. With the exception of carbohydrate composition, the results were consistent with the order of reactivity previously proposed from incubation studies with isotopically labelled substrates, namely: free > intra-aggregate > organomineral. The investigation illustrates the importance of using a range of different chemical characterisation techniques in studies of complex SOM fractions as each has limitations that could, if used alone, produce ambiguous findings or fail to detect differences between them.

While oxidation products of unsaturated fatty acids, for example dicarboxylic acids (hereafter diacids), must form during the use of unglazed ceramic vessels for the processing of animal and plant products, such components have never been observed during studies of absorbed lipids. Their absence from the extractable lipid fraction is presumed to be the result of their loss from potsherds through groundwater leaching. Lipid oxidation products including short–chain dicarboxylic acids, ω–hydroxy acids and longer–chain hydroxy and dihydroxy acids have now been observed as components probably covalently bound into solvent insoluble residues of potsherds recovered from waterlogged deposits. These components were only revealed following alkaline treatment of the insoluble residues. A similar mixture of diacids was observed in high abundance in the free lipid fraction of vessels recovered from an exceptionally arid deposit where groundwater leaching would never have occurred. These results confirm the formation of oxidation and probable polymerization products of unsaturated fatty acids during vessel use and burial.

ω‐(o‐Alkylphenyl)alkanoic acids are known to form in vitro from triunsaturated fatty acids following protracted heating. These compounds have recently been identified in absorbed lipid extracts obtained from archaeological pottery vessels, providing a potentially valuable new class of indicator for the processing of commodities, such as marine oils, which contain high abundances of polyunsaturated fatty acids. Experiments were conducted to assess whether ω‐(o‐alkylphenyl)alkanoic acids form when pure compounds and complex triacylglycerol mixtures are heated with a fired clay. The results demonstrate that ω‐(o‐alkylphenyl)alkanoic acids are only produced following heating of unsaturated fatty acids (tri‐, di‐ and monounsaturated species) or complex unsaturated fatty acyl lipids at around 270°C. Heating saturated fatty acyl lipids does not yield ω‐(o‐alkylphenyl)alkanoic acids. Thus, when searching for evidence for the processing of marine derived animal fats in archaeological pottery vessels, it is essential that: ω‐(o‐alkylphenyl)alkanoic acids of carbon length C 18 and C 20 should be present, ideally with C 22 also detectable (if only in trace abundances), together with at least one of the three isoprenoid fatty acids (phytanic, pristanic or 4,8,12‐tetramethyltridecanoic acid).

Partitioning of the quantities of C lost by leaf litter through decomposition into (i) CO2 efflux to the atmosphere and (ii) C input to soil organic matter (SOM) is essential in order to develop a deeper understanding of the litter-soil biogeochemical continuum. However, this is a challenging task due to the occurrence of many different processes contributing to litter biomass loss. With the aim of quantifying different fluxes of C lost by leaf litter decomposition, a field experiment was performed at a short rotation coppice poplar plantation in central Italy. Populus nigra leaf litter, enriched in 13C (δ13C ∼ +160‰) was placed within collars to decompose in direct contact with the soil (δ13C ∼ −26‰) for 11 months. CO2 efflux from within the collars and its isotopic composition were determined at monthly intervals. After 11 months, remaining litter and soil profiles (0–20 cm) were sampled and analysed for their total C and 13C content. Gas chromatography (GC), GC–mass spectrometry (MS) and GC-combustion-isotope ratio (GC/C/IRMS) were used to analyse phospholipid fatty acids (PLFA) extracted from soil samples to identify the groups of soil micro-organisms that had incorporated litter-derived C and to determine the quantity of C incorporated by the soil microbial biomass (SMB). By the end of the experiment, the litter had lost about 80% of its original weight. The fraction of litter C lost as an input into the soil (67 ± 12% of the total C loss) was found to be twice as much as the fraction released as CO2 to the atmosphere (30 ± 3%), thus demonstrating the importance of quantifying litter-derived C input to soils, in litter decomposition studies. The mean δ13C values of PLFAs in soil (δ13C = −12.5‰) showed sustained incorporation of litter-derived C after one year (7.8 ± 1.6% of total PLFA-C). Thus, through the application of stable 13C isotope analyses, we have quantified two major C fluxes contributing to litter decomposition, at macroscopic and microscopic levels.

13 C‐labelled glucose was applied to arable (Broadbalk NPK) and permanent grassland (Woburn Grassland) soils to investigate the response of the soil microbial biomass (SMB) to carbon (C) applied at trace concentrations. Phospholipid fatty acids (PLFA) were used as biomarkers for G+ve (odd‐chained and iso/anteiso FA) and G−ve bacteria (mono‐unsaturated and cyclic FA), actinobacteria (10‐methyl‐branched FA), fungi (octadecadienoic acid) and general membrane lipids [16:0,18:0]. Gas chromatography–combustion–stable isotope ratio mass spectrometry (GC‐C‐IRMS) was used to determine the incorporation of 13 C into individual PLFA in two experiments: first, after application of a single concentration (15 µg C g −1 ) of 13 C‐glucose over a time sequence (0, 8, 24, 48, 120 and 240 hours), and second after application at three concentrations (25, 83, 416 µg C g −1 soil after 120 hours). 13 C incorporation into PLFA over time was similar in both soils. However, in the permanent grassland soil, 13 C incorporation was increased in actinobacteria PLFA at 120 hours when [16:0,18:0] was reduced. At 240 hours, 13 C incorporation increased in [16:0,18:0] concurrently with a reduction in G+ve bacteria PLFA. Increasing glucose concentration caused different responses in the SMB of both soils. In the arable soil, all biomarker PLFA concentrations increased at all rates of application. In contrast, in the permanent grassland soil PLFA concentrations were similar to the control in all SMB groups, except G+ve bacteria after the greatest rate of application. However, the δ 13 C values of the same PLFA indicated that uptake of applied 13 C‐glucose was proportional to the applied concentration in all groups of soil bacteria in both soils.

The appearance of farming, from its inception in the Near East around 12 000 years ago, finally reached the northwestern extremes of Europe by the fourth millennium BC or shortly thereafter. Various models have been invoked to explain the Neolithization of northern Europe; however, resolving these different scenarios has proved problematic due to poor faunal preservation and the lack of specificity achievable for commonly applied proxies. Here, we present new multi-proxy evidence, which qualitatively and quantitatively maps subsistence change in the northeast Atlantic archipelagos from the Late Mesolithic into the Neolithic and beyond. A model involving significant retention of hunter-gatherer-fisher influences was tested against one of the dominant adoptions of farming using a novel suite of lipid biomarkers, including dihydroxy fatty acids, ω-(o-alkylphenyl)alkanoic acids and stable carbon isotope signatures of individual fatty acids preserved in cooking vessels. These new findings, together with archaeozoological and human skeletal collagen bulk stable carbon isotope proxies, unequivocally confirm rejection of marine resources by early farmers coinciding with the adoption of intensive dairy farming. This pattern of Neolithization contrasts markedly to that occurring contemporaneously in the Baltic, suggesting that geographically distinct ecological and cultural influences dictated the evolution of subsistence practices at this critical phase of European prehistory.

The n-alkane distributions from total lipid extracts of ten modern Sphagnum moss species, collected from a suite of ombrotrophic bogs across Europe, were determined using gas chromatography/mass spectrometry (GC/MS). n-Alkane distributions are reported for the first time for Sphagnum balticum, S. majus, S. angustifolium and S. lindbergii, which are all dominated by C23 with the exception of S. lindbergii, which exhibits a bimodal distribution with C23 and C31 as the major homologues. The distributions for individual species generally agree with published compositions, confirming the conservative nature of the n-alkane compositions, which provide a basis for differentiating the n-C23 and n-C25 dominated species. Investigations of the variation in n-C23/n-C25 and n-C23/n-C31 ratios of Sphagnum species, using the new and published n-alkane distributions, reveal that intra-species variation is generally minor. Critically, the distributions and ratios for most species do not vary among the sites studied, suggesting that they are conservative tracers for a given species, despite differences in growth conditions. In contrast, inter-species variation exists, allowing differentiation of individual Sphagnum species based on vegetation biomarkers, specifically the C25 n-alkane in S. fuscum and the n-C23/n-C25 ratio. Biomarker stratigraphic analysis of a 150 cm peat core (Kontolanrahka Bog, Finland) reveal shifts in the n-C23/n-C25 ratio, which track changes in the abundance of S. fuscum in the macrofossil record. This supports the application of n-alkane biomarkers in peat archives for tracking past shifts in individual Sphagnum species abundance. This will be particularly important where fossil plant remains are highly degraded in, or absent from, peat records.

Part of a large male woolly mammoth ( Mammuthus primigenius ) was preserved in permafrost in northern Yakutia. It was radiocarbon dated to ca. 18,500 14 C yr BP (ca. 22,500 cal yr BP). Dung from the lower intestine was subjected to a multiproxy array of microscopic, chemical, and molecular techniques to reconstruct the diet, the season of death, and the paleoenvironment. Pollen and plant macro-remains showed that grasses and sedges were the main food, with considerable amounts of dwarf willow twigs and a variety of herbs and mosses. Analyses of 110-bp fragments of the plastid rbcL gene amplified from DNA and of organic compounds supplemented the microscopic identifications. Fruit-bodies of dung-inhabiting Ascomycete fungi which develop after at least one week of exposure to air were found inside the intestine. Therefore the mammoth had eaten dung. It was probably mammoth dung as no bile acids were detected among the fecal biomarkers analysed. The plant assemblage and the presence of the first spring vessels of terminal tree-rings of dwarf willows indicated that the animal died in early spring. The mammoth lived in extensive cold treeless grassland vegetation interspersed with wetter, more productive meadows. The study demonstrated the paleoecological potential of several biochemical analytical techniques.

Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope values, a greater understanding of the complex biochemical and physiological factors which underpin bulk collagen δ15N values is necessary. Determinations of δ15N values of the individual amino acids which constitute bone collagen are necessary to unravel these relationships, since different amino acids display different δ15N values according to their biosynthetic origins. A range of collagen isolates from archaeological faunal and human bone (n = 12 and 11, respectively), representing a spectrum of terrestrial and marine protein origins and diets, were selected from coastal and near-coastal sites at the south-western tip of Africa. The collagens were hydrolysed and δ15N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ15N values reveals a 2‰ offset from bulk collagen δ15N values which is attributable to the δ15N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). The δ15N values of individual amino acids provide insights into both the contributions of various amino acids to the bulk δ15N value of collagen and the factors influencing trophic position and the nitrogen source at the base of the food web. The similarity in the δ15N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ15N value of threonine with increasing trophic level indicates a fundamental difference between the biosynthetic pathway of threonine and the other amino acids. The δ15N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ15NGlu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ15NGlu-Phe values. Differences in nitrogen metabolism are also shown to have an influence upon individual amino acid δ15N values with Δ15NGlu-Phe values emphasising differences between the different physiological adaptations. The latter is demonstrated in tortoises, which can excrete nitrogen in the form of uric acid and urea and display negative Δ15NGlu-Phe values whereas those for marine and terrestrial mammals are positive. The findings amplify the potential advantages of compound-specific nitrogen isotope analysis in the study of nitrogen flow within food webs and in the reconstruction of past human diets.

The invention of thermally resistant ceramic cooking vessels around 15,000 years ago was a major advance in human diet and nutrition1-3, opening up new food groups and preparation techniques. Previous investigations of lipid biomarkers contained in food residues have routinely demonstrated the importance of prehistoric cooking pots for the processing of animal products across the world4. Remarkably, however, direct evidence for plant processing in prehistoric pottery has not been forthcoming, despite the potential to cook otherwise unpalatable or even toxic plants2,5. In North Africa, archaeobotanical evidence of charred and desiccated plant organs denotes that Early Holocene hunter-gatherers routinely exploited a wide range of plant resources6. Here, we reveal the earliest direct evidence for plant processing in pottery globally, from the sites of Takarkori and Uan Afuda in the Libyan Sahara, dated to 8200-6400 bc. Characteristic carbon number distributions and δ13C values for plant wax-derived n-alkanes and alkanoic acids indicate sustained and systematic processing of C3/C4 grasses and aquatic plants, gathered from the savannahs and lakes in the Early to Middle Holocene green Sahara.

Research Article| April 01, 2012 Microbial lipid records of highly alkaline deposits and enhanced aridity associated with significant uplift of the Tibetan Plateau in the Late Miocene Shucheng Xie; Shucheng Xie * 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK *E-mail: xiecug@163.com. Search for other works by this author on: GSW Google Scholar Richard D. Pancost; Richard D. Pancost 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Search for other works by this author on: GSW Google Scholar Lin Chen; Lin Chen 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Richard P. Evershed; Richard P. Evershed 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Search for other works by this author on: GSW Google Scholar Huan Yang; Huan Yang 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Kexin Zhang; Kexin Zhang 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Junhua Huang; Junhua Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Yadong Xu Yadong Xu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Search for other works by this author on: GSW Google Scholar Author and Article Information Shucheng Xie * 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Richard D. Pancost 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Lin Chen 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Richard P. Evershed 2Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre and the Cabot Institute, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Huan Yang 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Kexin Zhang 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Junhua Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China Yadong Xu 1State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China *E-mail: xiecug@163.com. Publisher: Geological Society of America Received: 18 Jun 2011 Revision Received: 15 Oct 2011 Accepted: 27 Oct 2011 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2012 Geological Society of America Geology (2012) 40 (4): 291–294. https://doi.org/10.1130/G32570.1 Article history Received: 18 Jun 2011 Revision Received: 15 Oct 2011 Accepted: 27 Oct 2011 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Shucheng Xie, Richard D. Pancost, Lin Chen, Richard P. Evershed, Huan Yang, Kexin Zhang, Junhua Huang, Yadong Xu; Microbial lipid records of highly alkaline deposits and enhanced aridity associated with significant uplift of the Tibetan Plateau in the Late Miocene. Geology 2012;; 40 (4): 291–294. doi: https://doi.org/10.1130/G32570.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Saline alkaline sediments and soils are widespread in arid and semiarid regions, but their occurrence in ancient dry periods remains unknown due to the lack of a suitable proxy. On the basis of investigations of modern Chinese soils with a wide pH range of 3.5–9.1, we suggest that the microbial lipid ratio Ri/b, i.e., the abundance ratio of archaeal isoprenoid GDGTs (glycerol dialkyl glycerol tetraethers) to bacterial branched GDGTs, indicates the presence of drought-induced alkaline deposits in terrestrial settings. The Ri/b is invariant in modern soils with pH < 7.5 and when the local mean annual precipitation >600 mm, but it increases sharply at higher pH values and lower mean annual precipitation (<600 mm). In contrast, the CBT index (the cyclization ratio of branched GDGTs), which has been proposed to reflect environmental pH in other contexts, appears to be relatively stable in the highly alkaline Chinese soils from semiarid and arid regions investigated. We further explore the Ri/b ratio in a fluviolacustrine section in the Zhada basin of the southwestern Tibetan Plateau, covering the time period 9.2–2.6 m.y. ago. The Ri/b ratio remains relatively stable in most intervals but exhibits maxima in some horizons, indicative of the occurrence of severe drought and alkaline deposits in the basin catchment. These occur in fluvial sediments deposited 9 m.y. ago, a critical time with respect to the intensification of the East Asian and Indian monsoons, and the significant uplift of the plateau that has previously been associated with enhanced aridity in Central Asia. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Suspected coprolites from midden, burial and room fill contexts at Çatalhöyük were analysed by GC/MS and thin section micromorphology. Assessment of sterol biomarkers enabled a distinction between faecal and non-faecal sources for the deposits to be made, with bile acid biomarkers indicating that many of the faecal deposits are human coprolites. The relative lack of ruminant faeces could be due to this material being used as a fuel source. Deposits in burials were observed to contain soil and plant derived sterols rather than their faecal counterparts. Further analysis in thin section enabled identification of associated materials and contents. Diagnostic inclusions such as bone and plant fragments were only present in some of the human coprolites, which were observed to have a very similar morphology to decayed plant remains. This study illustrates the difficulties in distinguishing coprolites in the field and under the microscope, and demonstrates the importance of integrating biogeochemical methods, particularly when such deposits are used as the basis for interpreting human health and diet, and use-of-space in settlements.

The investigation of organic residues associated with archaeological pottery using modern analytical chemical methods began in the 1970s. It was recognised early on that the analysis of lipids (i.e. fats, waxes and resins) preserved in surface residues or the fabric of single potsherds, representative of single vessels, was a powerful method for ascertaining pottery use, with a high degree of specificity. Subsequent developments saw a significant change in scale, with studies often involving lipid analyses of tens to hundreds of potsherds per archaeological assemblage, providing information that extended beyond pottery use. The identification of animal and plant foodstuffs processed in pots provides insights into herding and farming, and can also detect trade in exotic organic goods. Information about the environment and climate can be extrapolated from the isotopic composition of compounds detected in potsherds, potentially providing novel avenues of investigation. The direct dating of lipids in potsherds is opening up new opportunities for building archaeological chronologies, while the integration of lipid residue analyses with other environmental and cultural proxies within interdisciplinary projects is already providing unprecedented insights into past lifestyles, from site to regional scales.

Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide direct evidence of crop growing conditions in the past and to refine palaeodietary predictions. If isotope values of archaeobotanical material are to be considered robust, it is necessary to characterise the compositional changes associated with their charring and burial. This study used a suite of analytical techniques, including FT-IR and solid state 13C NMR, to characterise changes in the biochemical composition of modern einkorn grains with heating at 230 °C for 2 h, 4 h, 8 h and 24 h, encompassing conditions that replicate their undistorted ancient counterparts. The biochemical composition of archaeobotanical charred einkorn grains was also investigated by FT-IR and solid state 13C NMR in order to assess the changes in composition which occur during burial. Results of FT-IR and solid-state 13C NMR show that heating of modern einkorn grains resulted in Maillard reactions between cereal proteins and starch, forming high molecular weight melanoidins, which contain both alkyl and aromatic carbon. Loss of low molecular weight carbon and nitrogen-containing volatiles resulted in a slight but non-systematic increase in the δ13C values and a systematic increase of 0.8‰ in the δ15N values of the charred einkorn grains. Solid-state 13C NMR shows that the ancient charred einkorn grains consisted entirely of aromatic carbon and retained a similar proportion of nitrogen to their modern 24 h charred counterparts, despite a significantly lower concentration of amino acids. This indicates that the amino acid nitrogen in the ancient charred grains was retained in the stable melanoidins whose polymeric structure makes them resistant to subsequent degradation.

The conventional ‘Neolithic package’ comprised animals and plants originally domesticated in the Near East. As farming spread on a generally northwest trajectory across Europe, early pastoralists would have been faced with the challenge of making farming viable in regions in which the organisms were poorly adapted to providing optimal yields or even surviving. Hence, it has long been debated whether Neolithic economies were ever established at the modern limits of agriculture. Here, we examine food residues in pottery, testing a hypothesis that Neolithic farming was practiced beyond the 60th parallel north. Our findings, based on diagnostic biomarker lipids and δ 13 C values of preserved fatty acids, reveal a transition at ca 2500 BC from the exploitation of aquatic organisms to processing of ruminant products, specifically milk, confirming farming was practiced at high latitudes. Combining this with genetic, environmental and archaeological information, we demonstrate the origins of dairying probably accompanied an incoming, genetically distinct, population successfully establishing this new subsistence ‘package’.

Molecular fossils (biomarkers) are abundant in organic rich natural archives such as peats and lignites (fossilized peat), where their distribution is governed by their biological source, environmental factors, such as temperature and pH, and diagenetic reactions. As a result, biomarkers in peat have become an important tool to study past variations in vegetation, environment and climate in terrestrial settings, as well as biogeochemistry on time-scales of hundreds to millions of years ago. In recent years, significant progress has been made in understanding the controls on biomarker distributions, especially those derived from microorganisms and peat-forming plants, allowing for example, the quantification of past temperature and vegetation history during peat formation. Herein, we provide a review of a range of commonly applied biomarker proxies in peats, discuss the latest proxy developments, and explore the potential of using biomarkers in peat and lignite as paleoenvironmental proxies. We provide a framework for biomarker analyses in peat and identify possible future research directions.

Covering extensive parts of China, karst is a critically important landscape that has experienced rapid and intensive land use change and associated ecosystem degradation within only the last 50 years. In the natural state, key ecosystem services delivered by these landscapes include regulation of the hydrological cycle, nutrient cycling and supply, carbon storage in soils and biomass, biodiversity and food production. Intensification of agriculture since the late-20th century has led to a rapid deterioration in Critical Zone (CZ) state, evidenced by reduced crop production and rapid loss of soil. In many areas, an ecological ‘tipping point’ appears to have been passed as basement rock is exposed and ‘rocky desertification’ dominates. This paper reviews contemporary research of soil processes and ecosystems service delivery in Chinese karst ecosystems, with an emphasis on soil degradation and the potential for ecosystem recovery through sustainable management. It is clear that currently there is limited understanding of the geological, hydrological and ecological processes that control soil functions in these landscapes, which is critical for developing management strategies to optimise ecosystem service delivery. This knowledge gap presents a classic CZ scientific challenge because an integrated multi-disciplinary approach is essential to quantify the responses of soils in the Chinese karst CZ to extreme anthropogenic perturbation, to develop a mechanistic understanding of their resilience to environmental stressors, and thereby to inform strategies to recover and maintain sustainable soil function.

Over the past three decades, studies of ancient biomolecules-particularly ancient DNA, proteins, and lipids-have revolutionized our understanding of evolutionary history. Though initially fraught with many challenges, today the field stands on firm foundations. Researchers now successfully retrieve nucleotide and amino acid sequences, as well as lipid signatures, from progressively older samples, originating from geographic areas and depositional environments that, until recently, were regarded as hostile to long-term preservation of biomolecules. Sampling frequencies and the spatial and temporal scope of studies have also increased markedly, and with them the size and quality of the data sets generated. This progress has been made possible by continuous technical innovations in analytical methods, enhanced criteria for the selection of ancient samples, integrated experimental methods, and advanced computational approaches. Here, we discuss the history and current state of ancient biomolecule research, its applications to evolutionary inference, and future directions for this young and exciting field.

The 8.2-thousand years B.P. event is evident in multiple proxy records across the globe, showing generally dry and cold conditions for ca. 160 years. Environmental changes around the event are mainly detected using geochemical or palynological analyses of ice cores, lacustrine, marine, and other sediments often distant from human settlements. The Late Neolithic excavated area of the archaeological site of Çatalhöyük East [Team Poznań (TP) area] was occupied for four centuries in the ninth and eighth millennia B.P., thus encompassing the 8.2-thousand years B.P. climatic event. A Bayesian analysis of 56 radiocarbon dates yielded a high-resolution chronological model comprising six building phases, with dates ranging from before 8325-8205 to 7925-7815 calibrated years (cal) B.P. Here, we correlate an onsite paleoclimate record constructed from δ2H values of lipid biomarkers preserved in pottery vessels recovered from these buildings with changes in architectural, archaeozoological, and consumption records from well-documented archaeological contexts. The overall sequence shows major changes in husbandry and consumption practices at ca. 8.2 thousand years B.P., synchronous with variations in the δ2H values of the animal fat residues. Changes in paleoclimate and archaeological records seem connected with the patterns of atmospheric precipitation during the occupation of the TP area predicted by climate modeling. Our multiproxy approach uses records derived directly from documented archaeological contexts. Through this, we provide compelling evidence for the specific impacts of the 8.2-thousand years B.P. climatic event on the economic and domestic activities of pioneer Neolithic farmers, influencing decisions relating to settlement planning and food procurement strategies.

The analysis of lipids and other biomolecules preserved in archaeological artefacts, using chromatographic and mass spectrometric techniques, is a powerful approach, which has provided unprecedented insights into the diet and cultural practices of past populations. In more recent years, the now-mature field of organic residue analysis (ORA) has entered a new phase, undertaking large scale analyses and providing broader perspectives on the uses of pottery over a range of both temporal and spatial scales. However, it has become apparent from the literature that there are significant pitfalls in applying the technique, often due to inexperience or lack of knowledge, that can lead to the production of data which is essentially worthless, because it either lacks analytical rigour or a valid archaeological interpretation. This is partly because ORA sits between chemistry and archaeology and projects are sometimes conducted by researchers not sufficiently familiar in the respective other discipline. Consequently, there have been numerous examples in recent years that showed a lack of understanding of critical points in ORA. This has two serious consequences: 1. the often-wide perpetuation of false knowledge, and 2. the use of a method that is both costly and destructive of irreplaceable archaeological material, which is not compensated for with useful information-gain. Here, we address some common errors encountered either in published literature or during peer-review and discuss the most important errors and misconceptions around ORA. In particular, we discuss use of unsuitable biomarkers, contamination, poor analytical data quality, the limitations of gas chromatography (GC), GC-mass spectrometry (GC-MS) and MS databases, and problems with the interpretation of ORA data. Here, we offer best practice advice and we hope that this will help, and encourage, all researchers looking to apply ORA in their studies, as we are optimistic that these pitfalls can be avoided, and the quality of published research consequently raised.

Micro and macroplastics are emerging contaminants in agricultural settings, yet their impact on nitrogen (N) cycling and partitioning in plant-soil-microbial systems is poorly understood. In this mesocosm-scale study, spring barley (Hordeum vulgare L.) was exposed to macro or microplastic produced from low density polyethylene (LDPE) or biodegradable plastic at concentrations equivalent to 1, 10 and 20 years of plastic mulch film use. Partitioning of 15N-labelled fertiliser into plant biomass, soil and leachate yielded a partial mass balance. Soil N partitioning was probed via compound-specific 15N-stable isotope analyses of soil microbial protein. Concentration-dependent decreases in plant 15N uptake occurred with increased leached nitrogen for LDPE microplastic. Assimilation into soil microbial protein was higher for biodegradable plastics, which we associate with early-stage biodegradable plastic degradation. Partitioning of 15N into inorganic soil N pools was affected by LDPE size, with lower assimilation into the microbial protein pool. While microplastics and macroplastics altered soil N cycling, the limited impacts on plant health indicated the threshold for negative effects was not reached at agriculturally relevant concentrations. This study highlights the difference between conventional and biodegradable plastics, and emphasises that the interplay of micro and macroplastics on soil N cycling must be considered in future studies.

Carbohydrates and proteins are among the most abundant naturally occurring biomolecules and so suitable methods for their reliable stable isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) are required. Due to the non-volatile nature of these compounds they require hydrolytic cleavage to their lower molecular weight subunits and derivatisation prior to GC/C/IRMS analysis. The addition of carbon to the molecules and any kinetic isotopic fractionation associated with derivatisation must be accounted for in order to provide meaningful stable isotope values and estimates of propagated errors. To illustrate these points amino acid trifluoroacetate/isopropyl esters and alditol acetates were prepared from authentic amino acids and monosaccharides, respectively. As predicted from the derivatisation reaction mechanisms, a kinetic isotope effect was observed which precludes direct calculation of delta(13)C values of the amino acids and monosaccharides by simple mass balance equations. This study shows that the kinetic isotope effect associated with derivatisation is both reproducible and robust, thereby allowing the use of correction factors. We show how correction factors can be determined and accurately account for the addition of derivative carbon. As a consequence of the addition of a molar excess of carbon and the existence of a kinetic isotope effect during derivatisation, errors associated with determined delta(13)C values must be assessed. We illustrate how such errors can be quantified (for monosaccharides +/-1.3 per thousand and for amino acids between +/-0.8 per thousand and +/-1.4 per thousand). With the magnitude of the errors for a given delta(13)C value of a monosaccharide or amino acid quantified, it is possible to make reliable interpretations of delta(13)C values, thereby validating the determination of delta(13)C values of amino acids as TFA/IP esters and monosaccharides as alditol acetates.

The detection of manuring in antiquity can provide important information concerning the agricultural and waste disposal practices of ancient communities. Faecal biomarkers provide a reliable and highly diagnostic method for detecting ancient faecal inputs to soils irrespective of any morphological remnants of manuring.

Compound-specific δD values recorded by means of gas chromatography–thermal conversion–isotope ratio mass spectrometry (GC–TC–IRMS) of the biomarker n-alkane (n-tricosane; n-C23) representative of the dominant Sphagnum species in a 40 cm peat profile from Bolton Fell Moss, Cumbria, UK, correlate with vegetation changes in the past >200 years (age depth model based on 210Pb dating). The bog vegetation is sensitive to climate change correlating with the global scale cooler period of the later 19th and early 20th centuries. The correlation with meteorological records suggests compound-specific δD values of lipid biomarkers have potential for use as a new climate proxy.

Structural and Isotopic (δ13C) evidence indicates the formation of series of long-chain ketones in archaeological pottery can occur by condensation of long-chain carboxylic acids. The formation of the ketones is confirmed by pyrolysis of free fatty acids or triacylglyecrols in the presence of fired clay matrix.

The excavation of a barrow at Upper Ninepence, Walton in the Welsh Borderlands, U.K., revealed two phases of occupation associated with two different ceramic traditions, namely Grooved Ware (2500bc) and Peterborough Ware (3000bc). The Grooved Ware and Peterborough Ware pits seem to have a mutually exclusive distribution on the site. Screening of the sherds for lipid residues has revealed the presence of remnant fats in a remarkably well-preserved state considering the age of the finds. Investigations of various chemical characteristics of the remnant fats from absorbed and carbonized residues have enabled distinctions to be drawn between fats from non-ruminant (e.g. porcine) and ruminant (e.g. ovine or bovine) origins. Significantly, both ruminant and non-ruminant fats are found associated with the Grooved Ware whereas only ruminant fats are found associated with the Peterborough Ware. The assignments are based upon the distributions of solvent-extractable lipid components and the compound-specific stable carbon isotope values of the major n -alkanoic acids. The results reveal differences in vessel use and indicate possible changes in patterns of animal exploitation or dietary preferences between the two phases of occupation. The results illustrate the importance of residue analysis in archaeological investigations, particularly at prehistoric sites where evidence from faunal remains is limited or absent.

Isotope ratio monitoring gas chromatography–mass spectrometry (irm GC–MS) was used to determine the δ13C values of individual compounds present in organic residues preserved in archaeological potsherds. The lipid fractions of the preserved organic residues were extracted from potsherds recovered from excavations performed as part of the Raunds Area Project, Northamptonshire, UK. The lipid extracts were analysed by high temperature GC and GC–MS. The leaf wax of a contemporary wild-type Brassica was also extracted and analysed for comparative purposes. Prior to irm GC–MS analysis, lipid extracts were fractionated; alkane and ketone fractions were obtained from the wild-type Brassica leaf wax, the total lipid extracts of two of the potsherds, and an archaeological soil sample using small-scale flash chromatography. The δ13C values obtained for the samples were consistent with the individual lipids investigated being of C3 plant origin. These data support the hypothesis that the lipids preserved in the potsherds were derived from a Brassica species such as cabbage. These results confirm the potential value of irm GC–MS to derive stable isotope ratios for individual lipid species of archaeological interest, and, more specifically, the potential for application of the technique to palaeodietary investigations.

The determination of the leafy vegetable constituents of the diets of early societies is notoriously difficult using traditional archaeobotanical techniques. In an effort to provide a solution to this problem, a new approach, using gas chromatography (GC) and GC/mass spectrometry (GC/MS), has been adopted to detect the presence of preserved epicuticular leaf wax components absorbed in potsherds. The characteristic compounds identified can serve as chemotaxonomic indicators of the vegetables prepared in vessels during their usage.

Coprostanol (5β-cholestan-3β-ol) is a metabolic product of cholesterol, formed by microbial action in the mammalian gut (the usual product of cholesterol reduction outside the gut, in mammalian tissues and sediments, is 5α-cholestan-3β-ol). Coprostanol is the major sterol in human faeces, and has been routinely studied as a marker of (modern) sewage pollution in marine and lacustrine sediments. This has led to the search for coprostanol in archaeological soils, in order to detect the presence of faecal material. Solvent extraction of the soil total lipids was followed by fractionation using thin layer chromatography, to isolate the steroids present in the soil. These were then analysed by combined gas chromatography/mass spectrometry (GC/MS), using selected ion monitoring (SIM) to detect and quantify specific compounds. Samples from a range of sources were analysed, including modern latrine deposits, a 17th-century garderobe, a mediaeval garderobe and two suspected Roman cess-pits. Coprostanol and its homologues were detected not only in the modern and aged cess samples, but also in the control samples, suggesting its ubiquitous occurrence in the environment, albeit at a low concentration. However, by measuring the relative abundances and ratios of the 5β-stanols, a chemical signature distinctive of faecal material could be established, independent of the simple occurrence of coprostanol in the soil. It was shown that coprostanol, and its homologues produced by the same microbial mechanism in the gut, were reliable markers of the presence of faeces in soils when found in the appropriate relative abundances. A method of analysing very small quantities of specific molecular marker compounds preserved in soils has thus been applied to archaeological materials, enabling a particular organic residue to be identified where conventional physical methods of analysis might not be successful.

In order to better interpret the origins of degraded fats and plant oils, experiments have been performed in the laboratory to simulate the decay of such commodities during burial. The progress of decay of various acyl lipids (milk and olive oil) and pure compounds (triolein and tristearin) has been monitored for up to 126 days. A general pattern emerged of a rapid decrease in triacylglycerol abundance with a concomitant increase in free fatty acids as a result of ester hydrolysis. The hydrolysis was assumed to be mediated largely by micro-organisms since this loss of triacylglycerol was accompanied by an overall consumption of lipid in all experiments. The appearance of microbial lipids occurred in the latter stages of degradation; these included short and long straight-chain, and branched-chain fatty acids ranging between C14 and C20. Ergosterol, a characteristic fungal marker, was also seen in the degradation experiment involving milk. The extent of incorporation of bacterial and fungal markers in decay experiments was minor (<2%) even in the case of highly degraded lipids (>90% consumed), thus fully legitimising the use of absorbed lipids in archaeological investigations.

Compound-specific stable carbon isotope analysis of amino acids by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is a highly selective and sensitive method for probing the biosynthetic/diagenetic pathways, pool size and turnover rates of proteins, previously intractable to bulk isotope analyses. However, amino acids are polyfunctional, non-volatile compounds which require derivatisation prior to GC analysis. While a wide range of derivatives exist for the GC analysis of amino acids only a handful have been utilised for their GC/C/IRMS analysis. Significantly, none of those derivatives currently employed appear completely satisfactory and a thorough assessment of their relative utility is lacking. Seven derivatives (three previously reported and four novel) for obtaining delta(13)C values of amino acids via GC/C/IRMS analysis were compared. More specifically, standard mixtures of 15 protein amino acids were converted into N-acetylmethyl (NACME) esters, N-acetyl n-propyl (NANP) esters, N-acetyl i-propyl (NAIP) esters, N-trifluoroacetyl-i-propyl (TFA-IP) esters, N-pivaloyl methyl (NPME) esters, N-pivaloyl n-propyl (NPNP) esters and N-pivaloyl i-propyl (NPIP) esters. Each derivative was assessed with respect to its applicability to carbon isotope determinations of all the common alpha-amino acids, reaction yield, chromatographic resolution, stability, analyte-to-derivative carbon ratio, kinetic isotope effects and errors associated with their carbon isotope determinations. The NACME derivative was concluded to be the preferred derivative mainly due to the highest analyte-to-derivative carbon ratio being achieved, resulting in the lowest analytical errors for amino acid delta(13)C value determinations, ranging from +/-0.6 per thousand for phenylalanine, leucine and isoleucine to +/-1.1 per thousand for serine and glycine.

Lipid residues from two Late Saxon/early medieval ceramic vessels recovered from excavations at West Cotton, Raunds, Northamptonshire, U.K., have been investigated by high‐temperature gas chromatography (GC) and GC/mass spectrometry (GC/MS). The solvent extracts of sherds sampled from different points on each vessel (i.e., base, body and rim) were analysed quantitatively and qualitatively and compounds were identified which were characteristic of beeswax and animal fat. Furthermore, by determining the sites of accumulation of the specific lipid types and their concentrations in different parts of the vessels it can be inferred that the beeswax was added to the vessels prior to the addition of the fat. It was concluded that the two vessels performed different functions in antiquity.

The introduction of 13C-labelled substrates to soils, sediments or cultures followed by 13C analysis of phospholipid fatty acids (PLFAs) provides quantitative and chemotaxonomic information for the groups of microorganisms utilizing a given substrate. Gas chromatography-combustion-isotope ratio mass spectrometry has provided the high precision necessary to measure small isotopic changes (differences in the relative abundances of 13C to 12C expressed as δ13C values) for nanogram amounts of individual compounds, such as microbial PLFAs. This methodology constitutes a powerful new culture-independent method for investigating microbial communities in the environment. The information obtained is highly complementary to that obtained from gene-probe-based methods, and considerable possibilities exist to extend this methodology to include other biochemical components of microorganisms.

Flash pyrolysis/gas chromatography (py/GC) and py/GC/mass spectrometry (MS) have been utilized to characterize the cuticles of invertebrates chemically. Pyrolysis products have been identified and assigned to specific cuticular components. Acetylpyridones, acetamidofuran, 3-acetamido-5-methylfuran and 3-acetamido-(2 and 4)-pyrones are proposed as characteristic pyrolysis markers for chitin. Pyrolysis products displaying ions of m/z 70, 154, 168, 194 are thought to derive from diketopiperazine structures and provide potential markers for proteins and peptides in which proline, alanine, valine, arginine and glycine are the dominant amino acids. These products, constituting specific pyrolysis markers for invertebrate cuticles, may reflect the amino acid composition of their constituent structural proteins. The source of the various pyrolysis products of proteins has been verified by pyrolysis of reference proteins, peptides and amino acid mixtures. The presence of additional pyrolysis products related directly to histidine and catechol moieties is consistent with the chemical structure and composition proposed for arthropod cuticles based on recent work utilizing solid state 13C and 15N nuclear magnetic resonance. This study constitutes the first comprehensive chemical characterization of the pyrolysis products of invertebrate cuticles and provides the basis for future investigations requiring qualitative screening for cross-linked chitin and proteins in modern and fossil cuticles and in materials, e.g. geopolymers, that may be derived from them.

Research Article| June 01, 2000 Alternative origin of aliphatic polymer in kerogen B.A. Stankiewicz; B.A. Stankiewicz 1Biogeochemistry Research Centre, Department of Earth Sciences, University of Bristol, Queen's Road, Bristol BS8 1RJ, UK Search for other works by this author on: GSW Google Scholar D.E.G. Briggs; D.E.G. Briggs 2Department of Earth Sciences, University of Bristol, Queen's Road, Bristol BS8 1RJ, UK Search for other works by this author on: GSW Google Scholar R. Michels; R. Michels 3UMR 7566 G2R CREGU, Université Henri Poincaré, Faculté des Sciences, BP239, 54501 Vandoeuvre les Nancy, France Search for other works by this author on: GSW Google Scholar M.E. Collinson; M.E. Collinson 4Department of Geology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK Search for other works by this author on: GSW Google Scholar M.B. Flannery; M.B. Flannery 5Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Search for other works by this author on: GSW Google Scholar R.P. Evershed R.P. Evershed 5Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Search for other works by this author on: GSW Google Scholar Author and Article Information B.A. Stankiewicz 1Biogeochemistry Research Centre, Department of Earth Sciences, University of Bristol, Queen's Road, Bristol BS8 1RJ, UK D.E.G. Briggs 2Department of Earth Sciences, University of Bristol, Queen's Road, Bristol BS8 1RJ, UK R. Michels 3UMR 7566 G2R CREGU, Université Henri Poincaré, Faculté des Sciences, BP239, 54501 Vandoeuvre les Nancy, France M.E. Collinson 4Department of Geology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK M.B. Flannery 5Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK R.P. Evershed 5Organic Geochemistry Unit, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Publisher: Geological Society of America Received: 03 Dec 1999 Revision Received: 13 Mar 2000 Accepted: 29 Mar 2000 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2000) 28 (6): 559–562. https://doi.org/10.1130/0091-7613(2000)28<559:AOOAPI>2.0.CO;2 Article history Received: 03 Dec 1999 Revision Received: 13 Mar 2000 Accepted: 29 Mar 2000 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation B.A. Stankiewicz, D.E.G. Briggs, R. Michels, M.E. Collinson, M.B. Flannery, R.P. Evershed; Alternative origin of aliphatic polymer in kerogen. Geology 2000;; 28 (6): 559–562. doi: https://doi.org/10.1130/0091-7613(2000)28<559:AOOAPI>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The origin of sedimentary organic matter (kerogen) has been attributed to random recombination reactions of biological components in sediments or to selective preservation of decay-resistant macromolecules. Neither hypothesis explains the aliphatic composition of the cuticle of fossil arthropods. Thermal maturation experiments on modern arthropods, involving confined pyrolysis at 250–360 °C, degrade the chitin-protein complex of the cuticle and transform free aliphatic components into a polymeric structure. The results of the application of electron microscopy and spectroscopic methods to modern, thermally matured, and fossil arthropod cuticles indicate that in situ polymerization of free and ester-bound cuticular lipids can lead to kerogen formation. Thus, fossil arthropod fragments can contribute to sedimentary organic matter. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

A buried, dark coloured loam soil horizon embedded between calcareous wind blown sand deposits is identified in three areas of the Tofts Ness landscape. The close association with early settlement sites and enhanced total phosophate levels suggests that this soil horizon is anthropogenic in origin. Radiocarbon dating and stratigraphic relationships with settlement sites indicate that the horizon is associated with Bronze Age cultural landscape activity and may have commenced formation during the Late Neolithic period. Horizon formation is interpreted through a synthesis of thin section micromorphology, stable carbon isotope analysis and analysis of free soil lipids. These analytical methods indicate that formation was through the application of grassy turf material together with domestic waste midden, while cultivation was moderately intense as evidenced by the movement of fine material through the horizon. The closest parallels to these soil horizons are the cultural plaggen soils of continental north west Europe, with the Tofts Ness soils amongst the earliest known of these soil types. Application of this manuring technique at Tofts Ness allowed arable activity in what was a highly marginal farming environment; emerging evidence from other parts of the Northern Isles of Scotland suggests that these manuring strategies were commonly used in early arable systems.

Studies of organic residues preserved in unglazed archaeological pottery have revealed the presence of homologous series of long-chain ketones containing 29–35 carbon atoms. The C31, C33 and C35 ketones are particularly abundant and exhibit a distinct monomidal distribution. The presence of long-chain ketones in potsherds is usually ascribed to the absorption of epicuticular waxes into the pottery fabric during the cooking of leafy vegetables. However, compound specific stable carbon isotope (δ13C) analyses of the individual lipids present in the potsherd extracts, in combination with detailed structural information, indicates that these ketones do not derive from plant waxes. Isotopic and structural analysis of the fatty acids, which always co-occur with the ketones, suggest that a precursor-product relationship exists. Micro-scale pyrolysis of a range of free fatty acids and triacylglycerols in the presence of various inorganic matrices was undertaken in exploring the possibility of an abiological route to the formation of the ketones. Depending on the pyrolysis conditions employed, substantial yields of long mid-chain ketones were formed which were structurally and isotopically congruent to those observed in the ancient potsherds. The ketones are formed by ketonic decarboxylation (a type of head to head condensation reaction), probably involving fatty acid metal salts as intermediates, the metal being provided by the inorganic matrix. Apart from the abundant long mid-chain ketones various other products such as methylketones, methyl esters, alkanes, alk-1-enes and homologous series of minor ketones are formed as secondary pyrolysis products. These latter products are not found in the pottery probably due to less vigorous thermal conditions achieved during the original use of the vessel compared with those attained in the laboratory pyrolysis experiments. Evidence for this comes from the formation of the fatty acid methyl esters which are only produced under the most forcing of pyrolysis conditions.

Absorbed lipid residue analysis has previously demonstrated that dairying was a major component of animal husbandry in Britain during both the Iron Age and Bronze Age. As a continuation of this research into the antiquity of dairying, the incidence of dairy fats associated with pottery vessels from six Neolithic sites from Southern Britain is presented herein. A total of 438 potsherds from Windmill Hill, Abingdon Causewayed Enclosure, Hambledon Hill, Eton Rowing Lake, Runnymede Bridge and Yarnton Floodplain were submitted for organic residue analysis. To date, this constitutes the largest number of sherds investigated from one particular archaeological period. The compound-specific stable isotope values of the major fatty acid components in animal fats, namely C16:0 and C18:0, enable absorbed lipids in pottery vessels to be classified to commodity group, i.e. ruminant adipose, dairy and non-ruminant adipose fats can be distinguished. The lipid extracts were relatively well preserved, and dairy fats were observed in approximately 25% of all of the sherds, demonstrating that milk was a valued commodity in the British Neolithic. These results confirm that dairying was an established component of the agricultural practices that reached Britain in the 5th Millennium BC.

The application of bone collagen stable carbon and nitrogen isotope analysis to human palaeodietary reconstruction in tropical or arid regions is limited by two factors: (i) the overlap in C4 and high marine protein (HMP) consumer bulk collagen δ13C values, and (ii) the unpredictability of bulk collagen δ15N values in regions of extreme aridity (<400 mm of rain per annum). Hence, the identification of HMP consumption among archaeological human populations can be problematic. In an endeavour to identify a more precise marine palaeodietary indicator, a range of collagen samples from archaeological faunal and human bone (n=14 and 26, respectively), representing a spectrum of C3, C4 and HMP diets, were selected from coastal and near-coastal sites in the Western Cape, South Africa. Samples were subjected to compound-specific stable carbon isotope analysis of their constituent amino acids as trifluoroacetyl-isopropyl (TFA-IP) esters via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). While human C4 and HMP consumers were indistinguishable with respect to bulk collagen δ13C values (−10.9±3.7‰ and −11.7±1.5‰, respectively) they were shown to be readily distinguished based on Δ13CGlycine-Phenylalanine values (+4.0±1.6‰ and +12.0±1.9‰, respectively). The relationship between HMP consumption and elevated Δ13CGlycine-Phenylalanine values was verified by: (i) the similarly elevated values exhibited by marine species when compared to terrestrial faunal species (+12.5±0.9‰ and +3.2±4.2‰, respectively), and (ii) the strong correlation observed between human Δ13CGlycine-Phenylalanine and bulk collagen δ15N values (R2=0.83, p<0.001; n=26), the latter being a well-documented marine dietary indicator. It was concluded that Δ13CGlycine-Phenylalanine values offer considerable potential as indicators of HMP consumption and a valuable substitute for bone collagen δ15N values in arid regions where bulk δ15N values are unpredictable.

Six samples of tar and pitch from the wreck of the Mary Rose (Tudor, AD 1509–45) and a sample of pitch from an Etruscan shipwreck (ca. 600 BC) have been analysed by a number of modern analytical techniques (elemental analysis, IR and NMR spectroscopy, GC and GC-MS). Similar analyses were performed on samples of contemporary tars, derived from natural sources, for comparative purposes. The major constituents of the archaeological samples were observed to be alkyl-substituted, tricyclic diterpenoids based on the abietane and pimarane skeletons. Similar molecular compositions and spectral properties were found for Stockholm tar (a good quality wood tar obtained by the destructive distillation of Pinus sylvestris), and Tudor and Etruscan pitches, thus providing conclusive evidence for the derivation of the archaeological samples from pine wood. The analytical techniques utilised are compared for their relative usefulness in chemical archaeology.

A modern experimental agricultural site was used to assess the possibility of using lipids as biomarkers of manuring in archaeological survey work. The modern experimental material originated from the Butser Ancient Farm site in Hampshire, U.K., where a plot under wheat cultivation had been subjected to manuring over half of its area for 13 years. A series of samples, including fresh dung, manure, and soil from manured, non-manured and control areas, was analysed in order to establish whether the application of manure results in enhanced biomarker abundance, specifically of 5β-stanols. Biomarker analysis involved extraction of total lipid from soil samples, fractionation by thin layer chromatography, and analysis by gas chromatography and gas chromatography/mass spectrometry using selected ion monitoring. A distinct enhancement of the specific 5β-stanol markers characteristic of cattle faeces/manure was found in the manured area when compared to the non-manured and control areas. The method thus holds considerable potential for archaeological application. The results from the biomarker analysis are compared to those from magnetic susceptibility measurement, total lipid and organic elemental C, H, and N analyses, and a range of inorganic elements. These comparisons served to highlight the potential advantages of the biomarker approach based on the 5β-stanols.

High performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI MS) was applied to the characterisation of triacylglycerols (TAGs) in animal fats. The major TAGs in four fats (beef, chicken, lamb and pork) were identified and positional isomers assigned according to their APCI mass spectra. Beef and lamb fat TAGs were confirmed as containing higher proportions of saturated fatty acids compared with those of chicken and pork. HPLC-APCI MS was also shown to be of value in providing regiospecific information for the fatty acids in individual TAG species. For example, beef and lamb fat were shown to contain both cis- and trans-isomers of the 18:1 fatty acid, whilst chicken and pork contained only the cis-isomer. When the position of fatty acid substitution was determined from the APCI spectra, whilst the cis- 18:1 was predominantly found in the 2-position of the TAG, the trans-18:1 showed a preference for the 1/3-position. Similarly, it was confirmed that although the 2-position of beef, chicken and lamb fat TAGs was dominated by unsaturated fatty acids, in pork fat, a characteristically high proportion of palmitic acid was seen in this position. The TAGs identified compared well with those reported previously. The distributions of 2-position fatty acids seen in lamb and pork fat compared favourably with those obtained by the more traditional method of lipase degradation. Although the distributions for chicken and beef showed some discrepancies, these can be attributed to weaknesses in the quantification procedure or the specificity of the lipase. Overall, the technique of HPLC-APCI MS has been shown to be very powerful for the regiospecific analysis of animal fats.

Ceramics are one of the major loci for the survival of organic residues of archaeological interest. The effects of post-depositional intrusion of soil organic matter on organic residues retained in the porous walls of pottery vessels has hitherto been largely overlooked. Gas chromatography (GC) and GC/mass spectrometry (GCMS), have been used to examine lipid constituents from freshly excavated potsherds and burial soil freed from the sherd surface. The GC analyses afford “fingerprint” profiles for these sherd/soil pairs, while GCMS allows characterization of individual lipid constituents present. The results show that in the majority of cases clear qualitative and quantitative distinctions can be drawn between the lipid constituents of the soil, arising from the decay of higher plants and micro-organisms, and those absorbed in the sherd during its period of use. These results lend further credence to the hypothesis that organic residue analysis can be used in conjunction with conventional ceramic data and contextual information to define vessel function.

Fragmentation of triacylglycerols by atmospheric pressure ionisation allows identification of positional isomers. The relative intensities of the [M-RCO2]+ ions provide information on the position of fatty acids within an ABC type triacylglycerol and enable ABA and AAB type molecules to be distinguished.

This paper reviews the occurrence of biomacromolecules in fossil plants and animals. The range of techniques used in their release, preparation, microscopy and chemical analysis is described, as is the role of decay experiments in their investigation. The major plant parts that include resistant macromolecules are discussed: algal cell walls, cuticles, spore and pollen walls, propagules, periderm, secondary xylem, and secretions. The chemistry of animal cuticles preserved in the fossil record is briefly considered; they may incorporate macromolecules of plant origin during diagenesis. Some future directions for research are outlined: characterization of sporopollenin, characterization of extant and extinct tissues and organs, chemosystematic investigations, taphonomic processes, investigation of biomacromolecules in animal fossils.

Long-term exposure of beta cells to lipids, particularly saturated fatty acids in vitro, results in cellular dysfunction and apoptosis (lipotoxicity); this could contribute to obesity-related diabetes. Our aims were to relate cell death to intracellular triglyceride concentration, composition and localisation following incubation of INS1 cells in saturated and unsaturated NEFA in high and low glucose concentrations.Insulin-producing INS1 cells were cultured (24 h; 3 and 20 mmol/l glucose) with palmitic, oleic or linoleic acids and the resulting intracellular lipids were analysed by gas chromatography and microscopy. Cell death was determined by quantitative microscopy and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and glucose-stimulated insulin secretion by ELISA.All NEFA (0.5 mmol/l, 0.5% albumin) inhibited glucose-stimulated (20 mmol/l) insulin secretion. Cytotoxicity was evident only with palmitic acid (p<0.05), in which case intracellular triglyceride consisted largely of tripalmitin in angular-shaped dilated endoplasmic reticulum. Cytotoxicity and morphological disruption were reduced by addition of unsaturated NEFA. Triglyceride content (control cells; 14.5 ng/mug protein) increased up to 10-fold following incubation in NEFA (oleic acid 153.2 ng/mug protein; p<0.05) and triglyceride and phospholipid fractions were both enriched with the specific fatty acid added to the medium (p<0.05).In INS1 cells, palmitic acid is converted in the endoplasmic reticulum to solid tripalmitin (melting point >65 degrees C), which could induce endoplasmic reticulum stress proteins and signal apoptosis; lipid-induced apoptosis would therefore be a consequence of the physicochemical properties of these triglycerides. Since cellular triglycerides composed of single species of fatty acid are not likely to occur in vivo, destruction of beta cells by saturated fatty acids could be predominantly an in vitro scenario.

Organic matter preservation is typically attributed to selective preservation of resistant biomolecules, random polymerisation of diagenetically degraded biomolecules (i.e. neogenesis) or in situ polymerisation of labile aliphatic components (in the case of fossil plants and insects). To evaluate these processes, we investigated the morphology and chemical structure of fossil leaves from the Ardèche diatomite (Late Miocene, southeast France) and compared them to their modern equivalents. Chemical analyses of the fossil leaves revealed the presence of a recalcitrant (non-hydrolysable) geopolymer comprised of benzene derivatives, lignin-derived components, pristenes and an aliphatic component; the latter consists partly of fatty acyl subunits ranging in carbon number from C8 to C32 with an abundance of C16 and C18 units. Chemical degradation of the modern plants failed to reveal the presence of the aliphatic biomacromolecule cutan, thereby precluding selective preservation of this compound as the source for the aliphatic component of the fossil leaves. In contrast, C16 and C18 fatty acyl units are predominant in the cutin and phospholipid fatty acid (PLFA) fractions of the modern leaves, while C10 to C32 acid units are characteristic of the free fatty acid (FA) fraction of epicuticular waxes. However, TEM and SEM investigations of the fossils revealed no evidence for cuticle preservation, and while a contribution from cutin cannot be excluded, the aliphatic component of the fossil polymer is possibly derived instead from the in situ polymerisation of labile cell membrane lipids and free fatty acids. A similar process involving lipid polymerisation has been observed previously in kerogen formation alongside selective preservation and, hence, may be important in organic matter preservation.

Summary Marine sediment slurries enriched for anaerobic, sulfate‐reducing prokaryotic communities utilizing glucose and acetate were used to provide the first comparison between stable‐isotope probing (SIP) of phospholipid fatty acids (PLFA) and DNA (16S rRNA and dsrA genes) biomarkers. Different 13 C‐labelled substrates (glucose, acetate and pyruvate) at low concentrations (100 µM) were used over a 7‐day incubation to follow and identify carbon flow into different members of the community. Limited changes in total PLFA and bacterial 16S rRNA gene DGGE profiles over 7 days suggested the presence of a stable bacterial community. A broad range of PLFA were rapidly labelled (within 12 h) in the 13 C‐glucose slurry but this changed with time, suggesting the presence of an active glucose‐utilizing population and later development of another population able to utilize glucose metabolites. The identity of the major glucose‐utilizers was unclear as 13 C‐enriched PLFA were common (16:0, 16:1, 18:1ω7, highest incorporation) and there was little difference between 12 C‐ and 13 C‐DNA 16S rRNA gene denaturing gradient gel electrophoresis (DGGE) profiles. Seemingly glucose, a readily utilizable substrate, resulted in widespread incorporation consistent with the higher extent of 13 C‐incorporation (∼10 times) into PLFA compared with 13 C‐acetate or 13 C‐pyruvate. 13 C‐PLFA in the 13 C‐acetate and 13 C‐pyruvate slurries were similar to each other and to those that developed in the 13 C‐glucose slurry after 4 days. These were more diagnostic, with branched odd‐chain fatty acids ( i 15:0, a 15:0 and 15:1ω6) possibly indicating the presence of Desulfococcus or Desulfosarcina sulfate‐reducing bacteria (SRB) and sequences related to these SRB were in the 13 C‐acetate‐DNA dsrA gene library. The 13 C‐acetate‐DNA 16S rRNA gene library also contained sequences closely related to SRB, but these were the acetate‐utilizing Desulfobacter sp., as well as a broad range of uncultured Bacteria. In contrast, analysis of DGGE bands from 13 C‐DNA demonstrated that the candidate division JS1 and Firmicutes were actively assimilating 13 C‐acetate. Denaturing gradient gel electrophoresis also confirmed the presence of JS1 in the 13 C‐DNA from the 13 C‐glucose slurry. These results demonstrate that JS1, originally found in deep subsurface sediments, is more widely distributed in marine sediments and provides the first indication of its metabolism; incorporation of acetate and glucose (or glucose metabolites) under anaerobic, sulfate‐reducing conditions. Here we demonstrate that PLFA‐ and DNA‐SIP can be used together in a sedimentary system, with low concentrations of 13 C‐substrate and overlapping incubation times (up to 7 days) to provide complementary, although not identical, information on carbon flow and the identity of active members of an anaerobic prokaryotic community.

Experimental maturation of plant tissue (350 °C, 700 bar) generates a resistant non-hydrolysable aliphatic macromolecule similar to that comprising organic matter in ancient sediments (kerogen). Comparison of the products derived from maturation of different pre-treated plant tissues clearly demonstrates that solvent-extractable and hydrolysable lipids are precursors of the generated macromolecular material. Thus, the experiments indicate that labile alkyl compounds can be a source of the insoluble aliphatic component of fossil organic matter and kerogen in the absence of a resistant aliphatic precursor (e.g. cutan) in the living organism.

The addition of small or trace amounts of carbon to soils can result in the release of 2–5 times more C as CO2 than was added in the original solution. The identity of the microorganisms responsible for these so-called trigger effects remains largely unknown. This paper reports on the response of individual bacterial taxa to the addition of a range of 14C-glucose concentrations (150, 50 and 15 and 0 μg C g−1 soil) similar to the low levels of labile C found in soil. Taxon-specific responses were identified using a modification of the stable isotope probing (SIP) protocol and the recovery of [14C] labelled ribosomal RNA using equilibrium density gradient centrifugation. This provided good resolution of the ‘heavy’ fractions ([14C] labelled RNA) from the ‘light’ fractions ([12C] unlabelled RNA). The extent of the separation was verified using autoradiography. The addition of [14C] glucose at all concentrations was characterised by changes in the relative intensity of particular bands. Canonical correspondence analysis (CCA) showed that the rRNA response in both the ‘heavy’ and ‘light’ fractions differed according to the concentration of glucose added but was most pronounced in soils amended with 150 μg C g−1 soil. In the ‘heavy RNA’ fractions there was a clear separation between soils amended with 150 μg C g−1 soil and those receiving 50 and 15 μg C g−1 soil indicating that at low C inputs the microbial community response is quite distinct from that seen at higher concentrations. To investigate these differences further, bands that changed in relative intensity following amendment were excised from the DGGE gels, reamplified and sequenced. Sequence analysis identified 8 taxa that responded to glucose amendment (Bacillus, Pseudomonas, Burkholderia, Bradyrhizobium, Actinobacteria, Nitrosomonas, Acidobacteria and an uncultured β-proteobacteria). These results show that radioisotope probing (RNA-RIP) can be used successfully to study the fate of labile C substrates, such as glucose, in soil.

Techniques for identifying organic residues in pottery have been refined over the years by Professor Evershed and his colleagues. Here they address the problem of radiocarbon dating these residues by accelerator mass spectrometry (AMS) which in turn dates the use of the pot. Fatty acids from carcass and dairy products cooked in the pot were isolated from early Neolithic carinated bowls found at the Sweet Track, Somerset Levels, England, and then dated by AMS. The results were very consistent and gave an excellent match to the dendrochronological date of the trackway. The method has wide potential for the precise dating of pottery use on sites.

Abstract Current research themes relating to prehistoric Central Asian pastoralism are discussed, and the Neolithic to Bronze archaeological sequence in Kazakhstan is briefly outlined. The results of new faunal analyses of six later Bronze Age sites in Central and Northern Kazakhstan are presented. These studies are based upon the analysis of 63,529 bone fragments, of which 27,023 were identifiable to species and element. These assemblages are compared with 16 other sites in Central and Northern Kazakhstan, and the Trans-Ural region. The herd structures at the final Bronze Age site of Kent are discussed in detail. Analyses of absorbed lipid residues from four sites are also presented. In total, 140 pottery sherds were analysed, of which 73 provided sufficient residues for stable isotope ratio determinations. It is concluded that species proportions are highly variable regionally. Cattle are most prevalent in the forest steppe zone, whilst caprines become more common in semi-arid steppe regions. Proportions of horse are particularly variable, even within environmentally similar areas. Lipid residue results indicate the high prevalence of ruminant dairy products in pottery vessels, whilst faunal data from Kent suggests that cattle husbandry might have been particularly focussed on milk, in comparison with sheep and goats. The significance of horses within prehistoric pastoralism is discussed.

Abstract An established method of estimating the trophic level of an organism is through stable isotope analysis of its tissues and those of its diet. This method has been used in archaeology to reconstruct past human diet from the stable nitrogen isotope (δ15N) values of human and herbivore bone collagen. However, this approach, using the 15N-enrichment of human bone collagen δ15N values over associated herbivore bone collagen δ15N values to predict the relative importance of animal protein, relies on the assumptions that: (i) the δ15N values of plants consumed by humans and herbivores are identical, and (ii) the 15N-enrichment between diet and consumer is consistent. Bone collagen amino acid δ15N values have the potential to tackle these uncertainties, as they constrain the factors influencing bone collagen δ15N values. In this study, the δ15N values of glutamic acid and phenylalanine in human and herbivore bone collagen isolates from Neolithic sites in Germany, Greece and Turkey were determined by gas chromatography-combustion-isotope ratio mass spectrometry. The fraction of animal protein in total dietary protein consumed by the humans was estimated by: (i) comparing bulk human and herbivore collagen δ15N values, (ii) comparing bulk human and herbivore collagen and ancient charred cereal grain δ15N values, (iii) comparing human bone collagen δ15NGlutamic acid and δ15NPhenylalanine values, and (iv) comparing δ15NGlutamic acid values of human and herbivore bone collagen and estimated δ15NGlutamic acid values of ancient charred cereal grains. Where determined cereal grain δ15N values are higher than estimated herbivore forage values, estimates of animal protein consumption are significantly lower, emphasising the importance of the plant nitrogen contribution to human bone collagen. This study also highlights the need for further investigation into: (i) the Δ15NConsumer-Diet values of glutamic acid and phenylalanine in terrestrial ecosystems, and (ii) Δ15NGlutamic acid-Phenylalanine values of common plant foods in order to improve the accuracy and more widespread applicability of amino acid-based methods for palaeodietary reconstruction.

Significance This research provides the earliest direct chemical evidence for the production of alcoholic beverage pulque in Mesoamerica, based on organic residues recovered from pottery vessels from Teotihuacan. A novel bacterial lipid biomarker approach is reported, which provides a new means of documenting the consumption of bacterially fermented alcoholic beverages in antiquity worldwide. At Teotihuacan, we have evidence that pulque was stored in distinctive amphorae vessels sealed with pine resin, as well as in other, less specialized vessels. Direct evidence of pulque production provides new insights into how the nutritional requirements of Teotihuacanos were sustained in a region in which the diet was largely based on plants and crop failures, due to drought and frost damage, which resulted in frequent shortfalls in staples.

This paper reports the first study applying a triple-isotope approach for source apportionment of polycyclic aromatic hydrocarbons (PAHs). The (13)C/(12)C, (14)C/(12)C, and (2)H/(1)H isotope ratios of PAHs were determined in forest soils from mountainous areas of the Czech Republic, European Union. Statistical modeling applying a Bayesian Markov chain Monte Carlo (MCMC) framework to the environmental triple isotope PAH data and an end-member PAH isotope database allowed comprehensive accounting of uncertainties and quantitative constraints on the PAH sources among biomass combustion, liquid fossil fuel combustion, and coal combustion at low and high temperatures. The results suggest that PAHs in this central European region had a clear predominance of coal combustion sources (75 ± 6%; uncertainties represent 1 SD), mainly coal pyrolysis at low temperature (∼650 °C; 61 ± 8%). Combustion of liquid fossil fuels and biomass represented 16 ± 3 and 9 ± 3% of the total PAH burden (∑PAH14), respectively. Although some soils were located close to potential PAH point sources, the source distribution was within a narrow range throughout the region. These observation-based top-down constraints on sources of environmental PAHs provide a reference for both improved bottom-up emission inventories and guidance for efforts to mitigate PAH emissions.

Two-dimensional compound-specific isotope analysis (2D-CSIA), combining stable carbon and chlorine isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs) in contaminated soil and groundwater. However, interpretation of 2D-CSIA data sets is challenged by a shortage of experimental Cl isotope enrichment factors. Here, isotope enrichments factors for C and Cl (i.e., εC and εCl) were determined for biodegradation of tetrachloroethene (PCE) and trichloroethene (TCE) using microbial enrichment cultures from a heavily CE-contaminated aquifer. The obtained values were εC = −5.6 ± 0.7‰ (95% CI) and εCl = −2.0 ± 0.5‰ for PCE degradation and εC = −8.8 ± 0.2‰ and εCl = −3.5 ± 0.5‰ for TCE degradation. Combining the values for both εC and εCl yielded mechanism-diagnostic εCl/εC ratios of 0.35 ± 0.11 and 0.37 ± 0.11 for the degradation of PCE and TCE, respectively. Application of the obtained εC and εCl values to a previously investigated field site gave similar estimates for the fraction of degraded contaminant as in the previous study, but with a reduced uncertainty in assessment of the natural attenuation. Furthermore, 16S rRNA gene clone library analyses were performed on three samples from the PCE degradation experiments. A species closely related to Desulfitobacterium aromaticivorans UKTL dominated the reductive dechlorination process. This study contributes to the development of 2D-CSIA as a tool for evaluating remediation strategies of CEs at contaminated sites.

Natural abundance δ15N values of plant tissue amino acids (AAs) reflect the cycling of N into and within plants, providing an opportunity to better understand environmental and anthropogenic effects on plant metabolism. In this study, the AA δ15N values of barley (Hordeum vulgare) and bread wheat (Triticum aestivum) grains and rachis and broad bean (Vicia faba) and pea (Pisum sativum) seeds, grown at the experimental farm stations of Rothamsted, UK and Bad Lauchstädt, Germany, were determined by GC–C–IRMS. It was found that the δ15N values of cereal grain and rachis AAs could be largely attributed to metabolic pathways involved in their biosynthesis and catabolism. The relative 15N-enrichment of phenylalanine can be attributed to its involvement in the phenylpropanoid pathway and glutamate has a δ15N value which is an average of the other AAs due to its central role in AA–N cycling. The relative AA δ15N values of broad bean and pea seeds were very different from one another, providing evidence for differences in the metabolic routing of AAs to the developing seeds in these leguminous plants. This study has shown that AA δ15N values relate to known AA biosynthetic pathways in plants and thus have the potential to aid understanding of how various external factors, such as source of assimilated N, influence metabolic cycling of N within plants.

Transhumance and palaeodiet are two central themes in archaeology and using chemical analysis of bones and teeth to reconstruct trends and patterns in diet and mobility has become a cornerstone of bioarchaeology. This study has investigated strontium concentration ([Sr]), radiogenic (87Sr/86Sr) and stable strontium (δ88Sr) isotope systematics in a controlled feeding experiment on domestic pigs designed to simulate terrestrial versus marine protein consumption. The results of the radiogenic (87Sr/86Sr) analysis offer a validation of the strontium isotope methodology. The study confirms that the radiogenic strontium isotope composition of dental enamel does represent the radiogenic strontium isotope composition of the diet. The results of the δ88Sr analysis have revealed a distinct shift of 0.322 ± 0.060 ‰ towards isotopically light Sr with trophic level. The magnitude of this shift is consistent with the predictions from the analogous shift observed in calcium isotopes. This is the first time that trophic level fractionation in δ88Sr has been identified in a controlled setting. Although still in its infancy, δ88Sr analysis has great potential to inform on trophic level systematics, to investigate dietary trends in early life and is potentially useful in examining diagenetic alteration.

The nature and extent to which hydrological changes induced by the Asian summer monsoon affected key biogeochemical processes remain poorly defined. This study explores the relationship between peatland drying and carbon cycling on centennial timescales in central China using lipid biomarkers. The difference between peat n-alkane δ2H and a nearby stalagmite δ18O record reveals that intervals of prominent peatland drying occurred during the mid-Holocene. Synchronous with these drier conditions, leaf wax δ13C values show large negative excursions, with the utilization of CO2 respired from the peatland subsurface for plant photosynthesis being a possible mechanism. Crucially, successive drying events appear to have had a cumulative impact on the susceptibility of peat carbon stores to climate change. Concurrently, bacterially derived hopane δ13C values suggest the occurrence of enhanced methane oxidation during the drier periods. Collectively, these observations expand our understanding of how respiration and degradation of peat are enhanced during drying events.