Archaeological bone lipids as palaeodietary markers.

RATIONALE: Stable isotope analysis of archaeological and fossil bone samples can provide important insights into past environments, ecologies and diets. Previous studies have focused on stable carbon and nitrogen isotopes in bone collagen, or carbon isotopes in bone mineral (bioapatite). Carbon isotope analysis of lipids from archaeological bone has received much less attention, partly due to the lack of suitable methodologies allowing sufficient recovery of compounds for structural and isotopic characterisation. Here we show that lipids can be easily and reliably recovered from archaeological bone using a modified protocol, and that these provide complementary dietary information to other bone components. METHODS: Human and animal bones were obtained from a variety of archaeological contexts. Lipids were sequentially extracted using solvent extraction (dichloromethane/methanol), followed by acidified methanol extraction (methanol/H2SO4). The lipids were then analysed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). RESULTS: Appreciable amounts of endogenous lipid were recovered from archaeological bone. Importantly, a comparison between compound-specific and bulk collagen isotopic data shows that archaeological bone lipids reflect dietary input and can be used to distinguish between marine and terrestrial consumers, as well as between C3 and C4 plant consumers. Furthermore, the presence of essential fatty acids directly incorporated from diet to bone may provide additional palaeodietary information. CONCLUSIONS: Our findings suggest that archaeological bone lipids are a hitherto untapped resource of dietary information that offer additional insights to those gained from other isotopic analyses of bone.

Imputation of ancient canid genomes reveals inbreeding history over the past 10,000 years.

The multi-millenia long history between dogs and humans has justly placed them at the forefront of archeological and genomic research. Despite ongoing efforts including the analysis of ancient dog and wolf genomes, many questions remain regarding their geographic and temporal origins, and the microevolutionary processes that led to the huge diversity of breeds today. Although ancient genomes provide valuable information, their use is significantly hindered by low depth of coverage and post-mortem damage, which often inhibits confident genotype calling. In the present study, we assess how genotype imputation of ancient dog and wolf genomes, utilising a large reference panel, can improve the resolution afforded by ancient genomic datasets. Imputation accuracy was evaluated by down-sampling 10 high coverage ancient and modern dog and wolf genomes to 0.05-2x coverage and comparing concordance between imputed and high coverage genotypes. We also measured the impact of imputation on principal component analyses (PCA) and runs of homozygosity (ROH). Our findings show high (R2 > 0.9) imputation accuracy for dogs with coverage as low as 0.5x and for wolves as low as 1.0x. We then imputed a worldwide dataset of 81 published ancient dog and wolf genomes, in addition to nine newly sequenced medieval and early modern period European dogs, to assess changes in inbreeding during the last 10,000 years of dog evolution. Ancient dog and wolf populations generally exhibited lower inbreeding levels than present-day individuals, though with some exceptions occurring in ancient Arctic and European dogs. Interestingly, regions with low ROH density maintained across ancient and present-day samples were significantly associated with genes related to olfaction and immune response. Our study indicates that imputing ancient canine genomes is a viable strategy that allows for the use of analytical methods previously limited to high-quality genetic data.

The history of Coast Salish "woolly dogs" revealed by ancient genomics and Indigenous Knowledge.

Ancestral Coast Salish societies in the Pacific Northwest kept long-haired "woolly dogs" that were bred and cared for over millennia. However, the dog wool-weaving tradition declined during the 19th century, and the population was lost. In this study, we analyzed genomic and isotopic data from a preserved woolly dog pelt from "Mutton," collected in 1859. Mutton is the only known example of an Indigenous North American dog with dominant precolonial ancestry postdating the onset of settler colonialism. We identified candidate genetic variants potentially linked with their distinct woolly phenotype. We integrated these data with interviews from Coast Salish Elders, Knowledge Keepers, and weavers about shared traditional knowledge and memories surrounding woolly dogs, their importance within Coast Salish societies, and how colonial policies led directly to their disappearance.

Ancient chicken remains reveal the origins of virulence in Marek's disease virus.

The pronounced growth in livestock populations since the 1950s has altered the epidemiological and evolutionary trajectory of their associated pathogens. For example, Marek's disease virus (MDV), which causes lymphoid tumors in chickens, has experienced a marked increase in virulence over the past century. Today, MDV infections kill >90% of unvaccinated birds, and controlling it costs more than US$1 billion annually. By sequencing MDV genomes derived from archeological chickens, we demonstrate that it has been circulating for at least 1000 years. We functionally tested the Meq oncogene, one of 49 viral genes positively selected in modern strains, demonstrating that ancient MDV was likely incapable of driving tumor formation. Our results demonstrate the power of ancient DNA approaches to trace the molecular basis of virulence in economically relevant pathogens.

Dual ancestries and ecologies of the Late Glacial Palaeolithic in Britain.

Genetic investigations of Upper Palaeolithic Europe have revealed a complex and transformative history of human population movements and ancestries, with evidence of several instances of genetic change across the European continent in the period following the Last Glacial Maximum (LGM). Concurrent with these genetic shifts, the post-LGM period is characterized by a series of significant climatic changes, population expansions and cultural diversification. Britain lies at the extreme northwest corner of post-LGM expansion and its earliest Late Glacial human occupation remains unclear. Here we present genetic data from Palaeolithic human individuals in the United Kingdom and the oldest human DNA thus far obtained from Britain or Ireland. We determine that a Late Upper Palaeolithic individual from Gough's Cave probably traced all its ancestry to Magdalenian-associated individuals closely related to those from sites such as El Mirón Cave, Spain, and Troisième Caverne in Goyet, Belgium. However, an individual from Kendrick's Cave shows no evidence of having ancestry related to the Gough's Cave individual. Instead, the Kendrick's Cave individual traces its ancestry to groups who expanded across Europe during the Late Glacial and are represented at sites such as Villabruna, Italy. Furthermore, the individuals differ not only in their genetic ancestry profiles but also in their mortuary practices and their diets and ecologies, as evidenced through stable isotope analyses. This finding mirrors patterns of dual genetic ancestry and admixture previously detected in Iberia but may suggest a more drastic genetic turnover in northwestern Europe than in the southwest.

Radiocarbon chronology and environmental context of Last Glacial Maximum human occupation in Switzerland.

Central Europe during the Last Glacial Maximum (LGM) was dominated by polar desert and steppe-tundra biomes. Despite this, a human presence during this time period is evident at several locations across the region, including in Switzerland, less than 50 km from the Alpine ice sheet margin. It has been hypothesised that such human activity may have been restricted to brief periods of climatic warming within the LGM, but chronological information from many of these sites are currently too poorly resolved to corroborate this. Here we present a revised chronology of LGM human occupation in Switzerland. AMS radiocarbon dating of cut-marked reindeer (Rangifer tarandus) bones from the sites of Kastelhöhle-Nord and Y-Höhle indicates human occupation of Switzerland was most likely restricted to between 23,400 and 22,800 cal. BP. This timeframe corresponds to Greenland Interstadial 2, a brief warming phase, supporting the hypothesis that human presence was facilitated by favourable climatic episodes. Carbon, nitrogen and sulphur stable isotope analysis of the fauna provides palaeoenvironmental information for this time period. These findings contribute to our understanding of human activity in ice-marginal environments and have implications for understanding cultural connections across central Europe during the LGM.

The problem with petrous? A consideration of the potential biases in the utilization of pars petrosa for ancient DNA analysis.

Advances in NGS sequencing technologies, improved laboratory protocols and new bioinformatic workflows have seen huge increases in ancient DNA (aDNA) research on archaeological materials. A large proportion of aDNA work now utilizes the petrous portion of the temporal bone (pars petrosa), which is recognized as an excellent skeletal element for long-term ancient endogenous (host) DNA survival. This has been significant due to the often low endogenous content of other skeletal elements, meaning that large amounts of sequencing are frequently required to obtain sufficient genetic coverage. However, exclusive sampling of the petrous for aDNA analysis introduces a new set of potential biases into our scientific studies - and these issues are yet to be considered by ancient DNA researchers. This paper aims to outline the possible biases of utilizing petrous bones to undertake aDNA analyses and highlight how these complications may potentially be overcome in future research.

Author Correction: Ancient genomes indicate population replacement in Early Neolithic Britain.

In the version of this Article originally published, there were errors in the colour ordering of the legend in Fig. 5b, and in the positions of the target and surrogate populations in Fig. 5c. This has now been corrected. The conclusions of the study are in no way affected. The errors have been corrected in the HTML and PDF versions of the article.

Ancient genomes indicate population replacement in Early Neolithic Britain.

The roles of migration, admixture and acculturation in the European transition to farming have been debated for over 100 years. Genome-wide ancient DNA studies indicate predominantly Aegean ancestry for continental Neolithic farmers, but also variable admixture with local Mesolithic hunter-gatherers. Neolithic cultures first appear in Britain circa 4000 BC, a millennium after they appeared in adjacent areas of continental Europe. The pattern and process of this delayed British Neolithic transition remain unclear. We assembled genome-wide data from 6 Mesolithic and 67 Neolithic individuals found in Britain, dating 8500-2500 BC. Our analyses reveal persistent genetic affinities between Mesolithic British and Western European hunter-gatherers. We find overwhelming support for agriculture being introduced to Britain by incoming continental farmers, with small, geographically structured levels of hunter-gatherer ancestry. Unlike other European Neolithic populations, we detect no resurgence of hunter-gatherer ancestry at any time during the Neolithic in Britain. Genetic affinities with Iberian Neolithic individuals indicate that British Neolithic people were mostly descended from Aegean farmers who followed the Mediterranean route of dispersal. We also infer considerable variation in pigmentation levels in Europe by circa 6000 BC.

Pathogens and host immunity in the ancient human oral cavity.

Calcified dental plaque (dental calculus) preserves for millennia and entraps biomolecules from all domains of life and viruses. We report the first, to our knowledge, high-resolution taxonomic and protein functional characterization of the ancient oral microbiome and demonstrate that the oral cavity has long served as a reservoir for bacteria implicated in both local and systemic disease. We characterize (i) the ancient oral microbiome in a diseased state, (ii) 40 opportunistic pathogens, (iii) ancient human-associated putative antibiotic resistance genes, (iv) a genome reconstruction of the periodontal pathogen Tannerella forsythia, (v) 239 bacterial and 43 human proteins, allowing confirmation of a long-term association between host immune factors, 'red complex' pathogens and periodontal disease, and (vi) DNA sequences matching dietary sources. Directly datable and nearly ubiquitous, dental calculus permits the simultaneous investigation of pathogen activity, host immunity and diet, thereby extending direct investigation of common diseases into the human evolutionary past.