Simon Mays

Comparative genomic and phylogeographic analysis of Mycobacterium leprae.

Reductive evolution and massive pseudogene formation have shaped the 3.31-Mb genome of Mycobacterium leprae, an unculturable obligate pathogen that causes leprosy in humans. The complete genome sequence of M. leprae strain Br4923 from Brazil was obtained by conventional methods (6× coverage), and Illumina resequencing technology was used to obtain the sequences of strains Thai53 (38× coverage) and NHDP63 (46× coverage) from Thailand and the United States, respectively. Whole-genome comparisons with the previously sequenced TN strain from India revealed that the four strains share 99.995% sequence identity and differ only in 215 polymorphic sites, mainly SNPs, and by 5 pseudogenes. Sixteen interrelated SNP subtypes were defined by genotyping both extant and extinct strains of M. leprae from around the world. The 16 SNP subtypes showed a strong geographical association that reflects the migration patterns of early humans and trade routes, with the Silk Road linking Europe to China having contributed to the spread of leprosy.

Stable carbon and nitrogen isotope variations in tooth dentine serial sections from Wharram Percy

Here we report δ13C and δ15N measurements of serial sections of human deciduous and permanent tooth dentine from archaeological samples taken from the medieval village site of Wharram Percy, Yorkshire, UK. We found a pattern of enrichment, for both δ13C and δ15N, where the tooth crown was greater than the cervical part of the root, which in turn was greater than the apical portion of the root and the associated rib collagen values. This pattern reflects a decrease in the consumption of isotopically enriched breast milk and the introduction of less enriched weaning foods in the diet. The (mean±SD) difference between the deciduous second molar crowns and corresponding rib samples from the same individuals after 2 years of age was 1.2±0.4‰ for δ13C and 3.2±0.8‰ for δ15N. The δ15N values are as predicted, but as there were no C4plants at Wharram Percy, this 1.2‰ enrichment in δ13C represents clear evidence of a carbon trophic level effect in collagen from breastfeeding infants. Carbon and nitrogen results also show that the infant diet among those who died in infancy did not differ from those who survived into childhood. This study demonstrates the promise of using dentine serial sections to study the temporal relationships of breastfeeding, weaning, and dietary patterns of single individuals.

Dry‐bone manifestations of rickets in infancy and early childhood

Rickets and osteomalacia are the subadult and adult expressions of a disease in which the underlying problem is a failure to mineralize bone protein (osteoid). The most common cause of this disease is a physiological deficiency in vitamin D. The associated problems include deformed bones and this condition is well known in pre-modern medical texts and documents as a fairly common cause of morbidity. Given these facts, it is surprising that the literature on palaeopathology provides very little evidence of this disease in archaeological human skeletal samples. The medieval sample (N=687) of human remains from Wharram Percy, North Yorkshire, England contains a remarkable subsample of eight burials in which a spectrum of pathological features is expressed. The subsample includes infants ranging in age from 3 to 18 months at the time of death. Ten abnormal bone features were identified in the subsample, including: (i) cranial vault porosity; (ii) orbital roof porosity; (iii) deformation of the mandibular ramus; (iv) deformation of arm bones; (v) deformation of leg bones; (vi) flared costo-chondral ends of ribs; (vii) irregular and porous cortex of the costo-chondral ends of the ribs; (viii) abnormality of the growth plates of long bones; (ix) irregular and porous surfaces of the metaphyseal cortex; (x) thickening of the long bones, particularly in the metaphyseal areas. Not all of these features were found in all of the cases. Nevertheless, the overall pattern of skeletal abnormality fits well with the anatomical and radiological conditions associated with rickets.

Age‐dependent cortical bone loss in a medieval population

Age-dependent cortical bone loss was studied in a skeletal assemblage from a British medieval site using metacarpal radiogrammetry. Significant loss of bone was found in the females but not in the males. The magnitude of bone loss in the older females relative to their younger counterparts was found to be similar to that reported for modern European subjects. Low cortical bone was associated with healed fractures of the highly trabecular bone of the axial skeleton, and this observation is suggestive that weakening of the skeleton due to loss of bone substance precipitated such fractures, as it does in modern Western women. The broad similarities between the medieval and modern data may call into question the importance of lifestyle factors in influencing the severity of osteoporosis, at least as far as loss of cortical bone is concerned.

Age-dependent cortical bone loss in women from 18th and early 19th Century London

Age-dependent cortical bone loss was investigated in an earlier British population. The study sample comprised female skeletons from the 18th/19th century crypt at Christ Church, Spitalfields, London. Bone loss was monitored using metacarpal radiogrammetry. Age at death was known exactly from coffin plates. Results indicated that peak cortical thickness was less than in modern subjects. Continuing periosteal apposition was evident throughout adulthood, and the rate of increase in metacarpal diameter resembled that in modern subjects. Bone loss from the endosteal surface was evident from the fifth decade onwards, and this outstripped the rate of subperiosteal gain so that there was a net loss of cortical bone with age. Cortical bone loss occurred at a similar rate to that in modern subjects. In contrast to modern populations, there was no evidence that loss of cortical bone was associated with increased propensity to fracture. The present results, together with those previously published for a British medieval skeletal assemblage, suggest that patterns of cortical bone loss in women have remained unchanged over at least the last millennium in Britain. Given the great changes in lifestyle which have occurred during this period, this suggests that lifestyle factors may be rather less important than is sometimes asserted in influencing the severity of osteoporosis, at least as far as loss of cortical bone is concerned.

Directional asymmetry in the human clavicle

The human right clavicle tends to be shorter than the left. A range of possible explanations can be advanced to account for this asymmetry. In the present work, clavicular morphology was studied in a medieval skeletal assemblage from Wharram Percy, England, with the aim of evaluating these competing explanations. At Wharram Percy, as anticipated, the right clavicle tended to be shorter. Patterns of asymmetry in curvature, robusticity, vascularization, and in the morphology of ligament and muscle attachment sites were also studied. The patterning in these data at Wharram Percy is consistent with inhibition of longitudinal growth of the clavicle on the dominant side due to lateral bias in mechanical loading, particularly in axial compression. Copyright

Age-dependent bone loss in the femur in a medieval population

Age-dependent bone loss in femurs in a medieval skeletal assemblage from Wharram Percy, England was studied. Dual energy X-ray absorptiometry (DXA) was used to measure bone mineral density (BMD) in the proximal femur; radiogrammetry was used to measure cortical index (FEMCI) at the femur mid-shaft. Age-related loss of BMD was found in the proximal femur in both sexes. Females but not males showed loss of FEMCI. Patterning in bone loss with respect to age, sex and site in the skeleton resembled that seen in recent subjects. In this respect the results are similar to those of a previous study of metacarpal cortical bone in the same archaeological assemblage. Given the large difference in lifestyles, and that lifestyle factors are widely held to influence the severity of bone loss in osteoporosis, the similarities between the medieval and modern populations in the patterns of bone loss are surprising. These findings support those from an earlier study of these skeletons in calling into question the role of lifestyle factors in influencing the severity of bone loss in osteoporosis.

Bone stable isotope evidence for infant feeding in Mediaeval England.

This paper is a first study of duration of breastfeeding using bone stable isotopes in infants in a British palaeopopulation, from the deserted Mediaeval village of Wharram Percy, England. Nitrogen stable isotope analysis suggests cessation of breastfeeding between 1 and 2 years of age. Comparison with Mediaeval documentary sources suggests that recommendations of physicians regarding infant feeding may have influenced common practice in this period.

Bone strontium: calcium ratios and duration of breastfeeding in a Mediaeval skeletal population

This work is an investigation of the value of bone strontium:calcium ratios in the study of duration of breastfeeding in earlier human populations. The study material comprised human skeletal remains of Mediaeval date from England. Investigation of diagenesis suggested that bone Sr:Ca ratios preserved a biogenic signal. Statistical analysis indicated significant age-related patterning in bone Sr:Ca ratios in the juvenile cohort. Duration of breastfeeding estimated from infant bone Sr:Ca ratios was concordant with that inferred from an earlier study of nitrogen stable isotope ratios from the same population. The value of bone Sr:Ca data for studying weaning practices in earlier human populations is discussed.

Molar crown height as a means of evaluating existing dental wear scales for estimating age at death in human skeletal remains

This study uses molar tooth crown heights of skeletons excavated from Poundbury cemetery, Dorset in order to evaluate Brothwells (1963) system for scoring molar wear for age estimation in adult skeletons from archaeological sites. Among the juveniles a highly significant relationship was found between crown height and dental age, confirming the utility of crown height in the study of individual age at death. In the group as a whole, wear (as measured by crown height) on teeth which are occlusal partners is strongly correlated, hence information loss by considering only upper or lower teeth is minor for the purposes of ageing. The remainder of the paper concentrates on mandibular molars. It appears that mandibular first and second molars wear at similar rates throughout life. Wear on the third molar is more variable and hence should be given less weight in age determination. The results confirm the value of dental wear for estimating age at death, and comparison of crown heights with Brothwells stages confirm the value of his scheme for scoring wear. However the definitions of some of Brothwells stages were found to be problematic, and in this light some revisions to his scheme are suggested. There are problems in applying tooth wear data to age older adults in archaeological populations, particularly as many of these show substantial ante-mortem loss of teeth. It is suggested that for archaeological populations young adults (aged about 17–35) may be distinguished from mature adults (aged about 35–55) on the basis of dental wear using Brothwells chart. In archaeological groups, adults showing losses of more than about 50% of their teeth ante-mortem are probably aged over about 55 years at death.