Biology subjects

Swali, P.

Publications and source records attributed to Swali, P..

6 recordsLinked to original sources

bioRxiv2026

The Genomic Landscape of Post-Black Death Epidemics in Northern Europe and the Caucasus

One of the most devastating events in human history, the Black Death (c.1347-1353), marked the beginning of the Second Plague Pandemic. After initially receding, plague returned in intermittent outbreaks throughout Europe, beginning with the pestis secunda. Despite its significance, the post-Black Death epidemiology of Yersinia pestis remains poorly understood. Here, we report 23 new Y. pestis genomes recovered from Second Plague Pandemic contexts across Scandinavia, the Netherlands, Iceland, and Armenia, spanning approximately 270 years. Applying a reproducible mutation-filtering pipeline to assess genetic diversity, we report both Black Death and post-Black Death lineages and document multiple waves of plague at individual cemetery sites. We identify four pestis secunda genomes, including three from Armenia, supporting the eastward dissemination of this lineage prior to its disappearance from Europe. We also resolve a previously under-characterised Branch 1A sub-lineage of Y. pestis and provide the first genomic evidence of plague in Iceland, resolving longstanding uncertainty over its presence on the island. Finally, by calling variants against a reconstructed ancestral reference, we identify clade-defining mutations, including nonsynonymous changes in metabolic and biofilm-related genes with predicted structural effects that may have contributed to shaping the epidemiological dynamics of the Second Plague Pandemic.

genetics↗

bioRxiv2026

Ancient DNA reveals matrilineal organisation and recurrent unions between dominant matrilines in Iron Age Britain

Kinship practices underpin all traditional societies, forming the basis for socially sanctioned reproductive unions, residence patterns and the inheritance of rights and property1,2. Although the relationship between biological relatedness and kinship is not always straightforward, ancient DNA studies are increasingly used to examine the extent to which biological relatedness underpinned social constructs of kinship in prehistoric societies3-6. Here, we report the analysis of genome-wide data for 534 individuals from the Arras Culture of Middle Iron Age northeast England (including 390 from Wetwang Slack, 100 from Pocklington, and 29 from Melton), finding evidence for communities with kinship systems structured along matrilineal lines. At Wetwang Slack, we reconstruct a 13-generation pedigree comprising 195 individuals structured around female-line connections: matrilineal transmissions greatly outnumbered patrilineal ones and male reproductive partners were largely absent from the cemetery, plausibly because they were buried in their own natal communities. Furthermore, the three main sites with robust sample sizes were characterised by non-overlapping dominant mitochondrial haplogroups, implying a maternal clan-based structure. Reproductive unions at Wetwang Slack suggest a recurrent alliance between two dominant maternal descent groups, with members of each group never reproducing with members of their own maternal lineage. Meanwhile, three individuals from lavishly furnished chariot burials at Wetwang Slack were close maternal relatives belonging to a lineage with consecutive generations of close kin unions, a pattern largely absent among other individuals at the site. These results indicate highly distinctive social practices among an elite group embedded in the wider kinship network of the Arras community.

genetics↗

bioRxiv2026

Genomic history and selection in Roman and early medieval Britain

Leading biomedical resources rely on genome variation in Britain1-3, but the historical processes that shaped present-day fine-scale diversity remain debated4-13. Here we sequenced 1039 ancient shotgun genomes from Britain (median 1.4-fold coverage), primarily dating to the first millennium CE. We imputed [~]660 million variants in the UK Biobank14-16 and employed genealogy-based ancestry reconstruction. We found an association between Iron Age consanguinity and matrilineal burial practices17, later disrupted following the Roman Conquest. Despite this societal impact, only 20% of Roman-period individuals carried detectable ancestry from outside Britain. In contrast, from the 6th century CE we detect widespread influx of ancestry in over 70% of individuals in southernAnglo-Saxon Britain, with limited local admixture. We find previously underappreciated heterogeneity, with ancestries associated with Central and Southern Europe rising in prevalence from the 7th century CE. We demonstrate distinct Scandinavian-related ancestry in many Viking-associated contexts, but show that the population-level impact of the Viking Age in Britain was limited. Finally, we detect pre-medieval selection on variants linked with key immunity genes TLR10-TLR1 and IRF8. These results identify population-level and selective processes that shape variation and disease risk in Britain today.

genomics↗

bioRxiv2026

AncientMetagenomeDir dating metadataset highlights need for standardised radiocarbon reporting in ancient DNA

Ancient DNA is a valuable data source for the understanding of our past. However, to effectively interpret this data, it is essential to know the age of the samples from which the DNA is obtained. Although the field of palaeogenomics has been recognised for its robust open data sharing practices, dating information associated with analysed samples is not reported consistently across palaeogenomic studies, nor is it included as metadata in most genetic data repositories. Here, we describe the addition of standardised precise dating information for ancient microbial genomes into the AncientMetagenomeDir metadata repository of published ancient metagenomic samples. This extension currently includes dating information for over 700 ancient microbial genomic datasets, of which 333 are dated using historical, contextual, or stratigraphic methods, and 405 are radiocarbon dated. We quantitatively assess the quality of radiocarbon date reporting and find that, despite established reporting conventions, radiocarbon dating information is often reported inconsistently across ancient metagenomic studies. This new resource provides ancient microbial researchers with standardised dating information that facilitates more accurate and consistent analysis of metagenomic sequencing data. The dataset also highlights the need for greater standardisation of radiocarbon date reporting in original publications in order to allow effective reuse of this and future ancient microbial data.

bioinformatics↗

bioRxiv2024

Ancient Borrelia genomes document the evolutionary history of louse-borne relapsing fever

Several disease-causing bacteria have transitioned from tick-borne to louse-borne transmission, a process associated with increased virulence and genome reduction. However, the historical time frame and speed of such evolutionary transitions have not been documented with ancient genomes. Here, we discover four ancient cases of Borrelia recurrentis, the causative agent of louse-borne relapsing fever, in Britain between [~]600 and 2,300 years ago, and sequence whole genomes up to 29-fold coverage. We estimate a recent divergence from the closest tick-borne ancestor, likely within the last [~]8,000 years. We reconstruct a chronology of gene losses and acquisitions using the pan-genome of related species, and show that almost all of the reductive evolution observed in B. recurrentis had occurred by [~]2,000 years ago, and was thus a rapid process after divergence. Our observations provide a new understanding of the origins of B. recurrentis and document complex reductive evolution in a specialist vector-borne pathogen.

evolutionary biology↗

bioRxiv2022

Yersinia pestis genomes reveal plague in Britain 4,000 years ago

Extinct lineages of Yersinia pestis, the causative agent of the plague, have been identified in several individuals from Central Europe and Asia between 5,000 and 3,500 years before present (BP). One of these, the LNBA lineage (Late Neolithic and Bronze Age), has been suggested to have spread into Central Europe with human groups expanding from the Eurasian steppes. Here, we show that LNBA plague was spread to Europes northwestern periphery by sequencing Yersinia pestis genomes from two individuals dating to ~4,000 cal BP from an unusual mass burial context in Somerset, England, UK. This represents the earliest evidence of plague in Britain documented to date. These British Yersinia pestis genomes belong to a sublineage previously observed in two Bronze Age individuals from Central Europe that had lost the putative virulence factor yapC. This sublineage is later found in Central Asia ~3,600 BP. While the severity of disease is currently unclear, the wide geographic distribution within a few centuries suggests substantial transmissibility.

evolutionary biology↗