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The core metabolism of microorganisms has a major influence on the hydrogen isotopic composition of their fatty acids. Heterotrophic microorganisms produce fatty acids with a deuterium to hydrogen (D/H) ratio either slightly depleted or enriched in D compared to the growth water, while photo- and chemoautotrophic microorganisms produce fatty acids which are heavily depleted in D. However, besides metabolism other biochemical and environmental factors (i.e. biosynthetic pathways, growth phase and temperature) have been shown to affect the D/H ratio of fatty acids, and it is necessary to evaluate the magnitude of these effects compared to that of metabolism. Here, we show that the effect of salinity on the D/H ratio of fatty acids depends on the core metabolism of the microorganism. While fatty acids of the photoautotroph Isochrysis galbana become more enriched in D with increasing salinity (enrichment of 30-40% over a range of 25 salinity units), no effect of salinity on the D/H ratio of fatty acids of the heterotrophic Pseudomonas str. LFY10 was observed (εlipid/water of the C16:0 fatty acid of ~120% over a range of 10 salinity units). This can likely be explained by the relative contributions of different H and nicotinamide adenine dinucleotide phosphate sources during fatty acid biosynthesis. [ABSTRACT FROM AUTHOR]

The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, αalkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to 35. αalkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85 ≤ R² ≤ 0.97; p < 0.0001) relationship between salinity and fractionation factor was observed in both species at all growth phases investigated. This suggests that alkenone δD has the potential to be used as a salinity proxy in neritic areas where haptophyte communities are dominated by these coastal species. However, there was a marked difference in the sensitivity of αalkenones-water to salinity between different growth phases: in the exponential growth phase of I. galbana, αalkenones-water increased by 0.0019 per salinity unit (S-1), but was less sensitive at 0.0010 and 0.0008 S-1 during the stationary and decline phases, respectively. Similarly, in C. lamellosa αalkenones-water increased by 0.0010 S-1 in the early stationary phase and by 0.0008 S-1 during the late stationary phase. Assuming the shift in sensitivity of αalkenones-water to salinity observed at the end of exponential growth in I. galbana is similar in other alkenone-producing species, the predominant growth phase of natural populations of haptophytes will affect the sensitivity of the alkenone salinity proxy. The proxy is likely to be most sensitive to salinity when alkenones are produced in a state similar to exponential growth. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogen isotope fractionation in alkenones produced by haptophyte algae is a promising new proxy for paleosalinity reconstructions. To constrain and further develop this proxy the coastal haptophyte Isochrysis galbana and the open ocean haptophyte alga Emiliania huxleyi were cultured at different salinities. The fractionation factor, α alkenones–water, ranged between 0.853 and 0.902 for I. galbana and 0.789 and 0.822 for E. huxleyi. The results show a strong linear correlation between the fractionation factor α and salinity for E. huxleyi, in agreement with earlier studies, but also for I. galbana. Both haptophytes show the same response to changes in salinity, represented by the slopes of the α–salinity relationship (∼0.002 per salinity unit). This suggests that the same process, in both coastal as well as open ocean haptophytes, is responsible for reducing fractionation with increasing salinity. However, there is a significant difference in absolute isotope fractionation between E. huxleyi and I. galbana, i.e. E. huxleyi produces alkenones which are 90‰ more depleted in D under the same culturing conditions than I. galbana. Our data suggest that the δD of alkenones can be used to reconstruct relative shifts in paleosalinity in coastal as well as open ocean environments with careful consideration of species composition and other complicating factors especially in coastal regions. [Copyright &y& Elsevier]

Abstract: Batch cultures of Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) were grown at salinity values of ca. 10 to ca. 35 and the alkenone distributions determined for different growth phases. values decreased slightly with salinity for C. lamellosa but were largely unaffected for I. galbana, except during the decline phase. The values decreased with incubation time in both species. The proportion of C37:4, used as a proxy for salinity, increased in both species at 0.16–0.20% per salinity unit, except during the stationary phase for I. galbana. C37:4 was much more abundant in C. lamellosa (30–44%) than in I. galbana (4–12%). Although our results suggest that salinity has a direct effect on alkenone distribution, growth phase and species composition should also have a marked impact, complicating the use of the distributions as a proxy for salinity in the marine environment. [Copyright &y& Elsevier]

Abstract Interdisciplinary scientific investigations utilising chemical analysis, shotgun metagenomics, textile analysis and radiocarbon dating have been applied to the study of an intact prehistoric Egyptian mummy, allowing insights into when this individual lived and died, and the funerary treatments employed in the preparation of the body. Here we present the first evidence for an extant prehistoric mummy that has undergone treatment with notably similar formative complex 'balms' that would later constitute the classic embalming recipes employed at the height of pharaonic mummification some 2500 years later. Making the informed assumption that the provenance of the Turin body was Gebelein, Qena or Luxor (Thebes), the findings offer the first indication that this type of funerary recipe was likely to have been employed over a wider geographical area at a time when the concept of a pan-Egyptian identity was supposedly still developing. Highlights • First extant prehistoric Egyptian mummy unequivocally treated with 'embalming agents'. • 'Balm' includes components (e.g. conifer resin) with antibacterial and preservative properties. • Reveals a spacio-temporal trend in funerary treatments that continued for millennia. [ABSTRACT FROM AUTHOR]

Santiago de Compostela is, together with Rome and Jerusalem, one of the three main pilgrimage and religious centres for Catholicism. The belief that the remains of St James the Great, one of the twelve apostles of Jesus Christ, is buried there has stimulated, since their reported discovery in the 9th century AD, a significant flow of people from across the European continent and beyond. Little is known about the practical experiences of people living within the city during its rise to prominence, however. Here, for the first time, we combine multi-isotope analysis (δ13C, δ15N, δ18Oap, δ13Cap and 87Sr/86Sr) and radiocarbon dating (14C) of human remains discovered at the crypt of the Cathedral of Santiago to directly study changes in diet and mobility during the first three centuries of Santiago’s emergence as an urban centre (9th–12th centuries AD). Together with assessment of the existing archaeological data, our radiocarbon chronology broadly confirms historical tradition regarding the first occupation of the site. Isotopic analyses reveal that the foundation of the religious site attracted migrants from the wider region of the northwest corner of the Iberian Peninsula, and possibly from further afield. Stable isotope analysis of collagen, together with information on tomb typology and location, indicates that the inhabitants of the city experienced increasing socioeconomic diversity as it became wealthier as the hub of a wide network of pilgrimage. Our research represents the potential of multidisciplinary analyses to reveal insights into the origins and impacts of the emergence of early pilgrimage centres on the diets and status of communities within Christian mediaeval Europe and beyond. [ABSTRACT FROM AUTHOR]

Considerable work has gone into developing high-precision radiocarbon (14C) chronologies for the southern Levant region during the Late Bronze to Iron Age/early Biblical periods (∼1200–600 BC), but there has been little consideration whether the current standard Northern Hemisphere 14C calibration curve (IntCal13) is appropriate for this region. We measured 14C ages of calendar-dated tree rings from AD 1610 to 1940 from southern Jordan to investigate contemporary 14C levels and to compare these with IntCal13. Our data reveal an average offset of ∼19 14C years, but, more interestingly, this offset seems to vary in importance through time. While relatively small, such an offset has substantial relevance to high-resolution 14C chronologies for the southern Levant, both archaeological and paleoenvironmental. For example, reconsidering two published studies, we find differences, on average, of 60% between the 95.4% probability ranges determined from IntCal13 versus those approximately allowing for the observed offset pattern. Such differences affect, and even potentially undermine, several current archaeological and historical positions and controversies. [ABSTRACT FROM AUTHOR]

The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought. [ABSTRACT FROM AUTHOR]

The extensive peat bogs of Southern Scandinavia have yielded rich Mesolithic archaeological assemblages, with one of the most iconic artefacts being the bone point. Although great in number they remain understudied. Here we present a combined investigation of the typology, protein-based species composition, and absolute chronology of Maglemosian bone points. The majority of the bone points are made from cervids and bovines. However, changes both in species composition and barb morphology can be directly linked to a paucity of finds lasting nearly 600 years in Southern Scandinavia around 10,300 cal BP. We hypothesize that this hiatus was climate-driven and forced hunter-gatherers to abandon the lakes. Furthermore, the marked change in bone points coincides with a change in lithic technology. We, therefore, propose that the Maglemose culture in Southern Scandinavia is fundamentally divided into an Early Complex and a Late Complex. [ABSTRACT FROM AUTHOR]

• Refined separation method allows the δ2H measurement of long-chain diols. • δ2H composition of long-chain diols of Nannochloropsis matches the growth medium. • Hydrogen isotopic ratios of C 32 1,15-diol reflects its origin in fresh river water. • Hydrogen isotopic ratios of C 30 1,15-diol reflects sea water isotopic composition. Long-chain diols (LCDs) are ubiquitous lipids produced by freshwater and marine algae. A combination of semi-preparative high performance liquid chromatography and gas chromatography isotope ratio monitoring mass spectrometry, allowed the measurement of δ2H of individual LCDs from cultures, which indicated a correlation with the hydrogen isotope composition of the growth water and a species-specific effect. Results from environmental samples along a salinity gradient indicated the potential of δ2H ratios of LCDs to trace the hydrogen isotopic composition of water and sea surface salinity. [ABSTRACT FROM AUTHOR]