Human genetic structure in Northwest France provides new insights into West European historical demography.

The demographical history of France remains largely understudied despite its central role toward understanding modern population structure across Western Europe. Here, by exploring publicly available Europe-wide genotype datasets together with the genomes of 3234 present-day and six newly sequenced medieval individuals from Northern France, we found extensive fine-scale population structure across Brittany and the downstream Loire basin and increased population differentiation between the northern and southern sides of the river Loire, associated with higher proportions of steppe vs. Neolithic-related ancestry. We also found increased allele sharing between individuals from Western Brittany and those associated with the Bell Beaker complex. Our results emphasise the need for investigating local populations to better understand the distribution of rare (putatively deleterious) variants across space and the importance of common genetic legacy in understanding the sharing of disease-related alleles between Brittany and people from western Britain and Ireland.

Glenoid retroversion: The palaeopathological perspective.

Retroversion of the glenoid articular plane has not received sufficient attention in palaeopathological studies. Occasionally mentioned in severe forms of osteoarthritis, exceptionally studied in extreme congenital forms isolated or in the context of malformation syndromes and overlooked in cases of minor dysplasia, it is nonetheless a valuable marker for identifying debilitating pathological conditions, abnormal shoulder laxity or sequelae of obstetric palsy. It is sometimes associated with other anomalies of the shoulder, the acromion or the coracoid processes of the scapula or the proximal end of the humerus. In this contribution, we first define a new method for measuring glenoid retroversion based on recent embryological and anatomical findings. This new method is particularly well adapted to archaeological remains for its simplicity and the possibility of using it with very fragmentary scapulae. We then applied it to eight pathological cases of various origins, dysplasias or acquired forms of glenoid retroversion; semiological analysis enabled the definition of diagnostic criteria for the main aetiologies. Several new diagnostic features are described, in particular for sequelae of obstetric palsy in adults.

Preservation of cell structures in a medieval infant brain: a paleohistological, paleogenetic, radiological and physico-chemical study.

Cerebral tissues from archaeological human remains are extremely rare findings. Hereby, we report a multidisciplinary study of a unique case of a left cerebral hemisphere from a 13th century AD child, found in north-western France. The cerebral tissue-reduced by ca. 80% of its original weight-had been fixed in formalin since its discovery. However, it fully retained its gross anatomical characteristics such as sulci, and gyri; the frontal, temporal and occipital lobe as well as grey and white matter could be readily recognised. Neuronal remains near the hippocampus area and Nissl bodies from the motor cortex area were observed (Nissl, Klüver-Barrera staining). Also, computed tomography (CT) and magnetic resonance imaging (T1, proton density, ultra short echo time sequences) were feasible. They produced high quality morpho-diagnostic images. Both histological and radiological examinations could not confirm the pathologist's previously suggested diagnosis of cerebral haemorrhage as the cause of death. Reproducible cloned mtDNA sequences were recovered from the skeleton but not from the brain itself. This was most likely due to the combined effect of formaldehyde driven DNA-DNA and/or DNA-protein cross-linking, plus hydrolytic fragmentation of the DNA. The chemical profile of the brain tissue, from gas-chromatography/mass-spectroscopy analysis, suggested adipocerous formation as the main aetiology of the mummification process. The hereby presented child brain is a unique paleo-case of well-preserved neuronal cellular tissue, which is a conditio sine qua non for any subsequent study addressing wider perspectives in neuroscience research, such as the evolution of brain morphology and pathology.