Mahoney, P., McFarlane, G., Pitfield, R., O’Hara, M., Miszkiewicz, J., Deter, C., Seal, H. and Guatelli-Steinberg, D. (2020). A structural biorhythm related to human sexual dimorphism. Journal of Structural Biology [Online] 211. Available at: https://www.sciencedirect.com/science/article/pii/S1047847720301234?dgcid=author.
Life on earth is regulated by biological rhythms, some of which oscillate with a circadian, monthly or lunar cycle. Recent research suggests that there is a near weekly biorhythm that may exert an influence on human skeletal growth. Evidence for the timing of this biorhythm is retained in tooth enamel as the periodicity of Retzius lines. Studies report that Retzius periodicity (RP) relates to adult human stature and enamel thickness. Adult human stature is sexually dimorphic, and so is enamel thickness of maxillary third molars (M3) but not mandibular M3. Yet, previous studies report sex differences in RP are apparent in some populations but not others, and it is unknown if dimorphism in enamel thickness relates to RP. To further our understanding of this biorhythm we analysed sex-related variation in RP and its relationship with enamel thickness in a sample of M3’s (n=94) from adults in Northern Britain.
Results reveal RP was significantly higher in our sample of female molars compared to those of males, which is consistent with the previously reported correlation between the biorhythm and adult stature. The RP of maxillary M3 related to sex differences in enamel thickness, but this relationship was not present in mandibular M3. Our results support previous findings suggesting that this biorhythm is sexually dimorphic and provide the first evidence that RP may be one factor influencing sex differences in enamel thickness. Our study also shows that correlations between RP and enamel thickness appear to be most readily detected for tooth types with sufficiently wide ranges of enamel thickness variation, as is the case for maxillary but not mandibular M3. Achieving a sufficient sample size was critical for detecting a sex difference in periodicity.
Aris, C., Mahoney, P. and Deter, C. (2020). Enamel growth rates of anterior teeth in males and females from modern and ancient British populations. American Journal of Physical Anthropology [Online]. Available at: https://onlinelibrary.wiley.com/doi/10.1002/ajpa.24068.
Objectives: This study explored biological sex differences in the regional daily growth rates of human anterior enamel from modern and ancient populations in Britain.
Methods: Maxillary permanent incisors (n=80) and canines (n=69) from Roman, Anglo-Saxon, Medieval, and Modern day populations were analysed using histological methods. Daily secretion rates (DSRs) were collected for inner, mid, and outer regions of cuspal and lateral enamel. Modern day samples were of known sex, archaeological individuals had sex determined using standard osteological methods. Variation in DSRs between the sexes, both between and within populations, was sought using parametric and non-parametric tests.
Results: When all samples were pooled, there was no significant difference between males and females. Similarly no significant differences in DSRs were identified between male and females within each population. When DSRs were compared between the populations, DSRs decreased from the more ancient to the more recent populations for males, and for females. More inter-population differences were observed in males.
Discussion: This study presents evidence for the relative consistency of enamel DSRs between male and female groups within each British population. Inter-population analyses found DSRs slowed significantly between Roman and modern day populations for both sexes, with male DSRs showing the greatest variation between populations.
Aris, C., Mahoney, P., O’Hara, M. and Deter, C. (2020). Enamel thickness and growth rates in modern human permanent first molars over a 2000 year period in Britain. American Journal of Physical Anthropology [Online]. Available at: https://onlinelibrary-wiley-com.chain.kent.ac.uk/doi/10.1002/ajpa.24026.
Objectives: This study explores variation and trends in first molar enamel thickness and daily enamel secretion rates over a 2000 year period in Britain. Methods: Permanent first molars (n=89) from the Roman, Anglo-Saxon, and Medieval periods, as well as modern day Britain, were analysed using standard histological methods. Relative enamel thickness (RET) and linear measurements of cuspal and lateral thickness were calculated for mesial cusps. Daily secretion rates (DSRs) were calculated for inner, mid, and outer enamel regions in both cuspal and lateral enamel. Significant differences and trends were identified between samples using non-parametric statistical tests. Results: Enamel thickness differed between some populations, but no temporal trends were identified. Early Anglo-Saxon molars had significantly thinner RET than both Late Anglo-Saxon (p<0.00) and Medieval (p<0.00) molars. Lateral enamel from the Roman molars was significantly thinner than the modern day sample (p=0.04). In contrast, DSRs slowed significantly from the more ancient to the modern day samples in every comparison except the mid lateral enamel region. Discussion:
This study presents the first evidence for a gradual slowing in the daily rate that enamel is secreted in molars over the past 2000 years in Britain. However, this trend was not matched by a change in enamel thickness, which remained fairly consistent over this time period. These findings suggest that modern human molars of similar enamel thickness, from different modern and ancient populations, formed at different rates.
Miszkiewicz, J., Louys, J., Beck, R., Mahoney, P., Aplin, K. and O’Connor, S. (2020). Island rule and bone metabolism in fossil murines from Timor. Biological Journal of the Linnean Society [Online] 129:570-586. Available at: https://academic.oup.com/biolinnean/advance-article/doi/10.1093/biolinnean/blz197/5709529?guestAccessKey=6de3dec9-93e0-48d8-a782-1c4516c6719f.
Skeletal growth rates reconstructed from bone histology in extinct insular hippopotamids, elephants, bovids, and sauropods have been used to infer dwarfism as a response to island conditions. Limited published records of osteocyte lacunae densities (Ot.Dn), a proxy for living osteocyte proliferation, have suggested a slower rate of bone metabolism in giant mammals. Here, we test whether insularity may have affected bone metabolism in a series of small to giant murine rodents from Timor. Ten adult femora were selected from a fossil assemblage dated to the Late Quaternary (ca. 5–18 ka). Femur morphometric data were used in computing phylogenetically-informed body mass regressions, although phylogenetic signal was very low (Pagel’s lambda = 0.03). Osteocyte lacunae densities from midshaft femur histological sections were evaluated against bone size and estimated body weight. Weight estimates calculated from these femora ranged from 75g to 1188g. Statistically significant (p < 0.05) and strongly negative relationships between Ot.Dn, femur size, and estimated weight were found. Larger specimens were characterised by lower Ot.Dn, indicating that giant murines from Timor may have had a relatively slow pace of bone metabolic activity, consistent with predictions made by the island rule.
Curto, A., Mahoney, P., Maurer, A., Barrocas-Dias, C., Fernandes, T. and Fahy, G. (2020). Effect of different healing stages on stable isotope ratios in skeletal lesions. American Journal of Physical Anthropology [Online] 171:285-297. Available at: https://onlinelibrary.wiley.com/doi/10.1002/ajpa.23958.
Introduction: This study compared stable isotope ratios from cortical bone (long bones and ribs) sites that retained evidence of healed or active disease, or healed fracture to isotope ratios from regions on the same bone that did not retain evidence of disease or fractures. Materials and methods: Carbon (δ13C) and nitrogen (δ15N) isotope ratios were assessed in 33 skeletons that retained evidence of infectious disease and healed fractures. Samples were taken from active lesions (long bones n=14; ribs n=4), healed lesions (long bones n=10; ribs n=9), or a fracture callus (long bones n=9; ribs n=3). Results were compared to stable isotope ratios calculated for regions on these bones that did not retain evidence of disease or fracture. Results: Long bones with active lesions had a significantly larger δ15N (δ15N=11.1±0.9‰) compared to those without lesions (δ15N=10.7±0.7‰; p=0.02). There were no significant differences in stable isotope ratios when compared between non-lesion and lesion sites in the ribs. Discussion: The increase in δ15N seen in active lesions, when compared with δ15N from non-lesion regions on the same long bone, may be a consequence of altered protein metabolism. This study suggests that stable isotope data can contribute information about diseases in the past, as well as an individuals’ response to diseases in the absence of modern medicine and antibiotics.
Schmidt, C., Remy, A., Van Sessen, R., Willman, J., Krueger, K., Scott, R., Mahoney, P., Beach, J., McKinley, J., d’Anastasio, R., Chiu, L., Buzon, M., de Gregory, J., Sheridan, S., Eng, J., Watson, J., Klaus, H., Da-Gloria, P., Wilson, J., Stone, A., Sereno, P., Droke, J., Perash, R., Stonanowski, C. and Herrmann, N. (2019). Dental microwear texture analysis of Homo sapiens sapiens: foragers, farmers, and pastoralists. American Journal of Physical Anthropology [Online] 169:207-226. Available at: https://doi.org/10.1002/ajpa.23815.
Objectives. The current study seeks to determine if a sample of foragers, farmers, and pastoralists can be distinguished by their dental microwear texture signatures.
Materials and Methods. The study included a sample of 719 individuals from 51 archaeological sites (450 farmers, 192 foragers, 77 pastoralists). All were over age 12 and sexes were pooled. Using a Sensofar® white-light confocal profiler we collected dental microwear texture analysis (DMTA) data from a single first or second molar from each individual. We leveled and cleaned data clouds following standard procedures and analyzed the data with Sfrax® and Toothfrax® software. The DMTA variables were complexity and anisotropy. Statistics included ANOVA with partial eta squared and Hedges's g. We also performed a follow-up K-means cluster analysis.
Results. We found significant differences between foragers and farmers and pastoralists for complexity and anisotropy, with foragers having greater complexity than either the farmers or the pastoralists. The farmers and pastoralists had greater anisotropy than the foragers. The Old World foragers had significantly higher anisotropy values than New World foragers. Old and New World farmers did not differ. Among the Old World farmers, those dating from the Neolithic through the Late Bronze Age had higher complexity values than those from the Iron Age through the medieval period. The cluster analysis discerned foragers and farmers but also indicated similarity between hard food foragers and hard food farmers.
Discussion. Our findings reaffirm that DMTA is capable of distinguishing human diets. We found that foragers and farmers, in particular, differ in their microwear signatures across the globe. There are some exceptions, but nothing that would be unexpected given the range of human diets and food preparation techniques. This study indicates that in general DMTA is an efficacious means of paleodietary reconstruction in humans.
Pitfield, R., Deter, C. and Mahoney, P. (2019). Bone histomorphometric measures of physical activity in children from Medieval England. American Journal of Physical Anthropology [Online] 169:730-746. Available at: http://dx.doi.org/10.1002/ajpa.23853.
Objectives: Histomorphometric studies show consistent links between physical activity patterns and the microstructure underlying the size and shape of bone. Here we adopt a combined bone approach to explore variation in microstructure of ribs and humeri related to physical activity and historical records of manual labor in skeletal samples of children (n=175) from medieval England. The humerus reflects greater biomechanically induced microstructural variation than the rib which is used here as a control. Variation in microstructure is sought between regions in England (Canterbury, York, Newcastle), and between high- and low-status children from Canterbury.
Materials and Methods: Thin-sections were prepared from the humerus or rib and features of bone remodeling were recorded using high-resolution microscopy and image analysis software.
Results: The density and size of secondary osteons in the humerus differed significantly in children from Canterbury when compared to those from York and Newcastle. Amongst the older children, secondary osteon circularity and diameter differed significantly between higher and lower status children.
Discussion: By applying bone remodeling principles to the histomorphometric data we infer that medieval children in Canterbury engaged in less physically demanding activities than children from York or Newcastle. Within Canterbury, high-status and low-status children experienced similar biomechanical loading until around seven years of age. After this age low-status children performed activities that resulted in more habitual loading on their arm bones than the high-status children. This inferred change in physical activity is consistent with historical textual evidence that describes children entering the work force at this age.
Curto, A., Mahoney, P., Maurer, A., Dias, C., Fernandes, T. and Fahy, G. (2019). Diet and disease in Tomar, Portugal: comparing stable carbon and nitrogen isotope ratios between skeletons with and without signs of infectious disease. Journal of Archaeological Science [Online] 105:56-69. Available at: https://doi.org/10.1016/j.jas.2019.03.005.
Objectives: This study explored the correspondence between stable isotope ratios and indicators of non-specific (periostitis and/or osteomyelitis) and specific (venereal syphilis) disease in a sample of human skeletons from a Portuguese archaeological collection. Additionally, this study examined stable carbon (δ13C) and nitrogen (δ15N) isotope ratios between individuals at different disease stages.
Materials and Methods: δ13C and δ15N data from previously analysed skeletons without signs of infectious disease or physiological stress (n=32) were compared to new data from skeletons with active (n=6), healed (n=7) or a combination of both lesions (n=10). Skeletons with lesions (n=23) were also grouped as having only healed tibial periostitis (n=7), generalised non-specific (n=5) and generalised specific infections (n=2). The skeletons with lesions that did not fit into these groups (n=9) were not used in this analysis.
Results: The δ15N from skeletons with non-specific generalised infections in several bones differed significantly when compared to skeletons that had either only healed tibial periostitis or were without lesions. Skeletons with venereal syphilis had similar mean δ13C and δ15N to either skeletons without signs of disease or those with only healed tibial periostitis.
Discussion: These results suggest different diets may be linked into an individual’s susceptibility to these pathogens. Diet influences resistance to infectious disease, while infections decrease nutrient availability, increase malabsorption and resting energy expenditure. Potentially therefore, combining isotopic evidence
of diet with pathology may contribute to a new understanding of health and lifestyle in the past.
Pitfield, R., Miszkiewicz, J. and Mahoney, P. (2019). Microscopic markers of an infradian biorhythm in human juvenile ribs. Bone [Online] 120:403-410. Available at: https://doi.org/10.1016/j.bone.2018.11.019.
Recent studies have indicated that there may be an infradian systemic biorhythm
that coordinates aspects of human hard tissue growth and influences adult body size. Here we
investigate if evidence of this biorhythm retained in human teeth as the periodicity of Retzius
lines (RP) corresponds with the microstructural growth of a non-weight bearing bone, the rib,
in a sample of 50 human juvenile skeletons. Using static histomorphometric methods, the RP
of one permanent tooth from each skeleton was calculated and combined with measures of
bone remodeling in a rib from the same individual. Results provide the first evidence that the
infradian biorhythm is linked to bone remodeling in children. Retzius periodicity was
negatively correlated with relative osteon area (r = -0.563, p = 0.008) and positively related to
Haversian canal area (r = 0.635, p = 0.002) and diameter (r = 0.671, p = 0.001) in children
between the age of 8 to 12 years. There was also a negative correlation between RP and the
relative cortical area of ribs (r = -0.500, p = 0.048). Relationships between bone remodeling
and the biorhythm were much more variable in younger children. Results imply that as the
biorhythm speeds up there is increased bone deposition during remodeling of the rib, leading
to the larger osteonal lamellar bone areas and smaller Haversian canals in children between 8
and 12 years of age. Our results support the idea that there is an infradian biorhythm that
coordinates aspects of human hard tissue growth.
Mahoney, P. (2019). Root growth and dental eruption in modern human deciduous teeth with preliminary observations on great apes. Journal of Human Evolution [Online] 129:46-53. Available at: https://doi.org/10.1016/j.jhevol.2018.12.011.
Recent studies of dental development have indicated that root growth rates are linked to the eruption of some permanent tooth types in modern humans and Pan troglodytes. Little is known about the potential links between these aspects of dental development in deciduous teeth of any primate species. This histology study calculates the rate at which roots extend in length for human deciduous maxillary teeth and a small sample of deciduous canines and premolars from Pan troglodytes and Pongo pygmaeus. Links are sought between root extension rates and previously published data for deciduous tooth emergence in each of these species. Results reported here provide the first evidence that the roots of human deciduous incisors, canines, and premolars extend in length at an accelerated rate as these teeth emerge. Accelerated extension rates in a deciduous canine from Pan coincided with the age that this tooth type emerged in captive chimpanzees. High extension rates in a canine from Pongo preceded emergence age. Preliminary observations indicate that deciduous canine and premolar roots of Pan and Pongo extend in length rapidly when compared to these tooth types from modern human children. This study provides a starting point from which to investigate new links between the incremental development of deciduous roots and tooth emergence in primates.
Miszkiewicz, J. and Mahoney, P. (2019). Histomorphometry and cortical robusticity of the adult human femur. Journal of Bone and Mineral Metabolism [Online] 37:90-104. Available at: https://doi.org/10.1007/s00774-017-0899-3.
Recent quantitative analyses of human bone microanatomy, as well as theoretical models that propose bone micro- and gross anatomical associations, have started to reveal insights into biological links that may facilitate remodeling processes. However, relationships between bone size and the underlying cortical bone histology remain largely unexplored. The goal of this study is to determine the extent to which static indicators of bone remodeling and vascularity, measured using histomorphometric techniques, relate to femoral midshaft cortical width and robusticity. Using previously published and new quantitative data from 450 adult human male (n = 233) and female (n = 217) femora, we determine if these aspects of femoral size relate to bone microanatomy. Scaling relationships are explored and interpreted within a context of tissue form and function. Analyses revealed that the area and diameter of Haversian canals and secondary osteons, and densities of secondary osteons and osteocyte lacunae from the sub-periosteal region of the posterior midshaft femur cortex were significantly, but not consistently, associated with femoral size. Cortical width and bone robusticity were correlated with osteocyte lacunae density and scaled with positive allometry. Diameter and area of osteons and Haversian canals decreased as the width of cortex and bone robusticity increased, revealing a negative allometric relationship. These results indicate that measures of cortical bone remodeling and vascularity products link to femur size. Allometric relationships between more robust human femora with thicker cortical bone and histological products of bone remodeling correspond with principles of bone functional adaptation. Future studies may benefit from combining bone histomorphometric data with measurements of bone macrostructure.
Curto, A., Mahoney, P., Fahy, G., Maurer, A., Barrocas-Dias, C. and Fernandes, T. (2018). Did military orders influence the general population diet? Stable isotopes analysis from Medieval Tomar, Portugal. Archaeological and Anthropological Sciences [Online]. Available at: https://doi.org/10.1007/s12520-018-0637-3.
This study integrates bone collagen stable isotope data (carbon, nitrogen and sulphur) from 33 human adult tibiae (15 females; 18 males) and 13 faunal remains from Tomar, while it was under the Military Orders domain (11th – 17th centuries). Historical literature indicates that the amount of meat consumption among Templars was lower than in individuals with similar social status. In medieval times these Military Orders had total control of towns and angling and fishing rights, but their influence on the general population diet remains unknown. While no statistically significant differences (p>0.05) were found between sexes, social status, or for bone collagen ?13C and ?34Sbetween age groups, ?15N did differ significantly with age, which may be related to tooth loss in old individuals. Additionally, the human samples have higher stable isotope differences, in comparison to faunal samples, than would be expected within the food web, particularly for ?13C. This human bone collagen ?13C enrichment may reflect a diet rich in aquatic protein intake, which is also supported by ?34S archived in human and faunal samples, and the presence of oysters and cockles shells at the excavation. The religious diet restrictions might have led to a higher intake of aquatic protein when meat consumption was not allowed.
Mahoney, P., Miszkiewicz, J., Chapple, S., Le Luyer, M., Schlecht, S., Stewart, T., Griffiths, R., Deter, C. and Guatelli-Steinberg, D. (2018). The Biorhythm of Human Skeletal Growth. Journal of Anatomy [Online] 232:26-38. Available at: http://dx.doi.org/10.1111/joa.12709.
Evidence of a periodic biorhythm is retained in tooth enamel in the form of Retzius lines. The periodicity of Retzius lines (RP) correlates with body mass and the scheduling of life history events when compared between some mammalian species. The correlation has led to the development of the inter-specific Havers-Halberg Oscillation (HHO) hypothesis, which holds great potential for studying aspects of a fossil species biology from teeth. Yet, our understanding of if, or how the HHO relates to human skeletal growth is limited. The goal here is to explore associations between the biorhythm and two hard tissues that form at different times during human ontogeny, within the context of the HHO. First, we investigate the relationship of RP to permanent molar enamel thickness and the underlying daily rate that ameloblasts secrete enamel during childhood. Following this, we develop preliminary research conducted on small samples of adult human bone by testing associations between RP, adult femoral length (as a proxy for attained adult stature), and cortical osteocyte lacunae density (as a proxy for the rate of osteocyte proliferation). Results reveal RP is positively correlated with enamel thickness, negatively correlated with femoral length, but weakly associated with the rate of enamel secretion and osteocyte proliferation. These new data imply that a slower biorhythm predicts thicker enamel for children but shorter stature for adults. Our results develop the intra-specific HHO hypothesis suggesting that there is a common underlying systemic biorhythm that has a role in the final products of human enamel and bone growth.
Fahy, G., Deter, C., Pitfield, R., Miszkiewicz, J. and Mahoney, P. (2017). Bone deep: variation in stable isotope ratios and histomorphometric measurements of bone remodelling within adult humans. Journal of Archaeological Science [Online] 87:10-16. Available at: https://doi.org/10.1016/j.jas.2017.09.009.
Stable carbon (?13C) and nitrogen (?15N) isotope studies of ancient human diet increasingly sample several skeletal elements within an individual. Such studies draw upon differences in bone turnover rates to reconstruct diet during different periods of time within an individual’s lifetime. Rib and femoral bone, with their respectively fast and slow remodeling rates, are the bones most often sampled to reconstruct shorter and longer term signals of diet prior to death. It is poorly understood if ?13C and ?15N vary between bone types within a single individual, or if this variation corresponds with bone turnover rate (BTR). Here, we determined ?13C and ?15N for ten different bones from ten adult human skeletons (n=5 males; n=5 females). Isotope values were compared to the rate that each bone remodeled, calculated from osteon population (OPD) density. Results reveal that isotope ratios varied within each skeleton (?13C: max= -1.58‰; ?1542 N: max= 3.05‰). Humeri, metacarpals, and ribs had the highest rate of bone remodelling; the occipital bone had the lowest. A regression analyses revealed that higher rates of bone remodeling are significantly and negatively correlated with lower ?15N. Our results suggest that the occipital bone, with its slow rate of bone renewal, may prove useful for isotopic studies that reconstruct diet over longer periods of time within an individual’s lifetime. Isotope studies that compare individual skeletal elements between populations should standardize their methodology to bones with either a slow or fast turnover rate.
Pitfield, R., Miszkiewicz, J. and Mahoney, P. (2017). Cortical histomorphometry of the human humerus during ontogeny. Calcified Tissue International [Online] 101:148-158. Available at: http://dx.doi.org/10.1007/s00223-017-0268-1.
Modeling and remodeling are two key determinants of human skeletal growth though little is known about the histomorphometry of cortical bone during ontogeny. In this study we examined the density and geometric properties of primary and secondary osteons (osteon area and diameter, vascular canal area and diameter) in sub-periosteal cortical bone from the human humerus (n=84) between birth and age 18 years. Sections were removed from the anterior midshaft aspect of humeri from skeletons. Age-at-death was reconstructed using standard osteological techniques. Analyses revealed significant correlation between the histomorphometric variables and age. Higher densities of primary osteons occurred between infancy and seven years of age but were almost completely replaced by secondary osteons after 14 years of age. The geometry of primary osteons was less clearly related to age. Secondary osteons were visible after two years of age, and reached their greatest densities in the oldest individuals. Osteon size was positively but weakly influenced by age. Our data implies that modeling and remodeling are age dependent processes that vary markedly from birth to adulthood in the human humerus.
Mahoney, P., Miszkiewicz, J., Pitfield, R., Deter, C. and Guatelli-Steinberg, D. (2017). Enamel biorhythms of humans and great apes: the Havers-Halberg Oscillation hypothesis reconsidered. Journal of Anatomy [Online] 230:272-281. Available at: http://dx.doi.org/10.1111/joa.12551.
The Havers-Halberg Oscillation (HHO) hypothesis links evidence for the timing of a biorhythm retained in permanent tooth enamel (Retzius periodicity) to adult body mass and life history traits across mammals. Potentially, these links provide a way to access life history of fossil species from teeth. Recently we assessed intra-specific predictions of the HHO on human children. We reported Retzius periodicity (RP) corresponded with enamel thickness, and cusp formation time, when calculated from isolated deciduous teeth. We proposed the biorhythm might not remain constant within an individual. Here, we test our findings. RP is compared between deciduous second and permanent first molars within the maxillae of four human children. Following this, we report the first RPs for deciduous teeth from modern great apes (n = 4), and compare these with new data for permanent teeth (n = 18) from these species, as well as with previously published values. We also explore RP in teeth that retain hypoplastic defects. Results show RP changed within the maxilla of each child, from thinner to thicker enameled molars, and from one side of a hypoplastic defect to the other. When considered alongside correlations between RP and cusp formation time, these observations provide further evidence that RP is associated with enamel growth processes and does not always remain constant within an individual. RP of 5 days for great ape deciduous teeth lay below the lowermost range of those from permanent teeth of modern orangutan and gorilla, and within the lowermost range of RPs from chimpanzee permanent teeth. Our data suggest associations between RP and enamel growth processes of humans might extend to great apes. These findings provide a new framework from which to develop the HHO hypothesis, which can incorporate enamel growth along with other physiological systems. Applications of the HHO to fossil teeth should avoid transferring RP between deciduous and permanent enamel, or including hypoplastic teeth.
Parker Pearson, M., Chamberlain, A., Jay, M., Richards, M., Sheridan, A., Curtis, N., Evans, J., Gibson, A., Mahoney, P., Marshall, P., Montgomery, J. and Needham, S. (2016). Beaker people in Britain: migration, mobility and diet. Antiquity [Online] 90:620 -637. Available at: http://www.dx.doi.org/10.15184/aqy.2016.72.
The appearance of the distinctive ‘Beaker package’ marks an important horizon in British prehistory, but was it associated with immigrants to Britain or with indigenous converts? Analysis of the skeletal remains of 264 individuals from the British Chalcolithic–Early Bronze Age is revealing new information about the diet, migration and mobility of those buried with Beaker pottery and related material. Results indicate a considerable degree of mobility between childhood and death, but mostly within Britain rather than from Europe. Both migration and emulation appear to have had an important role in the adoption and spread of the Beaker package.
Mahoney, P., Schmidt, C., Deter, C., Remy, A., Slavin, P., Johns, S., Miszkiewicz, J. and Nystrom, P. (2016). Deciduous enamel 3D microwear texture analysis as an indicator of childhood diet in medieval Canterbury, England. Journal of Archaeological Science [Online] 66:128-136. Available at: http://dx.doi.org/10.1016/j.jas.2016.01.007.
This study conducted the first three dimensional microwear texture analysis of human deciduous teeth to reconstruct the physical properties of medieval childhood diet (age 1-8yrs) at St Gregory's Priory and Cemetery (11th to 16th century AD) in Canterbury, England. Occlusal texture complexity surfaces of maxillary molars from juvenile skeletons (n=44) were examined to assess dietary hardness. Anisotropy values were calculated to reconstruct dietary toughness, as well as jaw movements during chewing. Evidence of weaning was sought, and variation in the physical properties of food was assessed against age and socio-economic status. Results indicate that weaning had already commenced in the youngest children. Diet became tougher from four years of age, and harder from age six. Variation in microwear texture surfaces was related to historical textual evidence that refers to lifestyle developments for these age groups. Diet did not vary with socio-economic status, which differs to previously reported patterns for adults. We conclude, microwear texture analyses can provide a non-destructive tool for revealing subtle aspects of childhood diet in the past.
Mahoney, P., Miszkiewicz, J., Pitfield, R., Schlecht, S., Deter, C. and Guatelli-Steinberg, D. (2016). Biorhythms, deciduous enamel thickness, and primary bone growth in modern human children: a test of the Havers-Halberg Oscillation hypothesis. Journal of Anatomy [Online] 228:919-928. Available at: http://dx.doi.org/10.1111/joa.12450.
Across mammalian species, the periodicity with which enamel layers form (Retzius periodicity) in permanent teeth corresponds with average body mass and the pace of life history. According to the Havers-Halberg Oscillation hypothesis (HHO), Retzius periodicity (RP) is a manifestation of a biorhythm that is also expressed in lamellar bone. Potentially, these links provide a basis for investigating aspects of a species’ biology from fossilized teeth. Here, we tested intra-specific predictions of this hypothesis on skeletal samples of human juveniles. We measured daily enamel growth increments to calculate RP in deciduous molars (n=25). Correlations were sought between RP, molar average and relative enamel thickness (AET, RET), and the average amount of primary bone growth (n=7) in humeri of age-matched juveniles.
Results show a previously un-described relationship between RP and enamel thickness. Reduced major axis regression reveals RP is significantly and positively correlated with AET and RET, and scales isometrically. The direction of the correlation was opposite to HHO predictions as currently understood for human adults. Juveniles with higher RPs and thicker enamel had increased primary bone formation, which suggests a coordinating biorhythm. However, the direction of the correspondence was again, opposite to predictions. Next, we compared RP from deciduous molars to new data for permanent molars, and to previously published values. The lowermost RP of four and five days in deciduous enamel extends below the lowermost RP of six days in permanent enamel. A lowered range of RP values in deciduous enamel implies that the underlying biorhythm might change with age. Our results develop the intra-specific HHO hypothesis.
Miszkiewicz, J. and Mahoney, P. (2015). Ancient Human Bone Microstructure in Medieval England: Comparisons between Two Socio-Economic Groups. The Anatomical Record [Online] 299:42-59. Available at: http://dx.doi.org/10.1002/ar.23285.
Understanding the links between bone microstructure and human lifestyle is critical for clinical and anthropological research into skeletal
growth and adaptation. The present study is the first to report correspondence between socio-economic status and variation in bone microstructure
in ancient humans. Products of femoral cortical remodeling were assessed using histological methods in a large human medieval
sample (N:450) which represented two distinct socio-economic groups. Osteonal parameters were recorded in posterior midshaft femoral sections
from adult males (N:233) and females (N:217). Using univariate and multivariate statistics, intact, fragmentary, and osteon population densities, Haversian canal area and diameter, and osteon area were compared between the two groups, accounting for sex, age, and estimated femoral robusticity. The size of osteons and their Haversian canals, as well as osteon density, varied significantly between the socio-economic groups, although minor inconsistencies were observed in
females. Variation in microstructure was consistent with historical textual evidence that describes differences in mechanical loading and
nutrition between the two groups. Results demonstrate that aspects of ancient human lifestyle can be inferred from bone microstructure.
Mahoney, P. (2015). Dental fast track: Prenatal enamel growth, incisor eruption, and weaning in human infants. American Journal of Physical Anthropology [Online] 156:407-421. Available at: http://dx.doi.org/10.1002/ajpa.22666.
Correlation between the timing of permanent first molar eruption and weaning age in extant primates has provided a way to infer a life history event in fossil species, but recent debate has questioned whether the same link is present in human infants. Deciduous incisors erupt at an age when breast milk can be supplemented with additional foods (mixed feeding), and weaning is typically complete before permanent first molars erupt. Here, I use histological methods to calculate the prenatal rate by which enamel increases in thickness and height on human deciduous incisors, canines, and molars (n = 125). Growth trajectories for each tooth type are related to the trimesters and assessed against the eruption sequence and final crown height. Analyses show that central incisors initiate early in the second trimester with significantly faster secretion rates relative to canines and second molars, which initiate closer to birth. Even though initial extension rates were correlated with crown height and scaled with positive allometry within each tooth class, the relatively short incisors still increased in height at a significantly faster rate than the taller canines and molars. The incisor prenatal “fast track” produces a greater proportion of the crown before birth than all other tooth types. This growth mechanism likely facilitates early incisor eruption at a time when the mixed feeding of infants can be initiated as part of the weaning process. Findings provide a basis from which to explore new links between developmental trends along the tooth row and mixed feeding age in other primates.
Mahoney, P. (2013). Testing functional and morphological interpretations of enamel thickness along the deciduous tooth row in human children. American Journal of Physical Anthropology [Online] 151:518-525. Available at: http://dx.doi.org/10.1002/ajpa.22289.
The significance of a gradient in enamel thickness along the human permanent molar row has been debated in the literature. Some attribute increased enamel thickness from first to third molars to greater bite force during chewing. Others argue that thicker third molar enamel relates to a smaller crown size facilitated by a reduced dentin component. Thus, differences in morphology, not function, explains enamel thickness. This study draws on these different interpretive models to assess enamel thickness along the entire human deciduous tooth row. Average enamel thickness (AET), the area and proportion of crown enamel and dentin, and a crown size proxy are calculated for incisors, canines, and molars. Allometric scaling relationships are assessed within each tooth class, and then comparisons are undertaken along the row. Generally, AET was correlated with crown size and scaled with isometry, except for second molars which scaled with positive allometry. Mean AET increased along the row and was greater on molars, where bite forces are reported to be higher. Second molars combined the largest crown size with the thickest enamel and the smallest proportion of dentin, which is consistent with a reduction in the potential for cusp fracture under high bite forces. Resistance to wear may also account for some enamel thickness variation between tooth classes. Dental reduction did not explain the trend in AET from central to lateral incisors, or from first to second molars. The gradient in AET along the deciduous tooth row is partly consistent with a functional interpretation of enamel thickness. Am J Phys Anthropol 151:518–525, 2013. © 2013 Wiley Periodicals, Inc.
Mahoney, P. (2012). Incremental Enamel Development in Modern Human Deciduous Anterior Teeth. American Journal of Physical Anthropology [Online] 147:637-351. Available at: http://dx.doi.org/10.1002/ajpa.22029.
This study reconstructs incremental enamel development for a sample of modern human deciduous mandibular (n = 42) and maxillary (n = 42) anterior (incisors and canines) teeth. Results are compared between anterior teeth, and with previous research for deciduous molars (Mahoney: Am J Phys Anthropol 144 (2011) 204–214) to identify developmental differences along the tooth row. Two hypotheses are tested: Retzius line periodicity will remain constant in teeth from the same jaw and range from 6 to 12 days among individuals, as in human permanent teeth; daily enamel secretion rates (DSRs) will not vary between deciduous teeth, as in some human permanent tooth types. A further aim is to search for links between deciduous incremental enamel development and the previously reported eruptionsequence. Retzius line periodicity in anterior teeth ranged between 5 and 6 days, but did not differ between an incisor and molar of one individual. Intradian line periodicity was 12 h. Mean cuspal DSRs varied slightly between equivalent regions along the tooth row. Mandibular incisors initiated enamel formation first, had the fastest mean DSRs, the greatest prenatal formation time, and based upon prior studies are the first deciduous tooth to erupt. Relatively rapid development in mandibular incisors in advance of early eruption may explain some of the variation in DSRs along the tooth row that cannot be explained by birth. Links between DSRs, enamel initiation times, and the deciduous eruption sequence are proposed. Anterior crown formation times presented here can contribute toward human infant age-at-death estimates. Regression equations for reconstructing formation time in worn incisors are given.
Mahoney, P. (2011). Human deciduous mandibular molar incremental enamel development. American Journal of Physical Anthropology [Online] 144:204-214. Available at: http://dx.doi.org/10.1002/ajpa.21386.
Quantitative studies of incremental markings retained within human enamel have reconstructed the duration and rate (crown and cusp formation times, initiation and completion, daily enamel secretion rates) of permanent tooth development. This approach has provided one way of estimating human age-at-death, and facilitated comparative dental studies of primate evolution. Similar applications from deciduous enamel are inhibited because developmental reconstructions from incremental markings for these teeth are less frequently reported in the literature. This study quantified the duration and rate of enamel development for mesial (protoconid, metaconid) and distal cusps (hypoconid, entoconid) for first (dm1) and second (dm2) deciduous mandibular molars from an archaeological sample of modern human juveniles. Crown formation time can be calculated from the dm1 protoconid because growth initiates and completes in this cusp, and from the dm2 protoconid combined with the final period of hypoconid growth. The dm1 postnatal crown formation time included the time taken for the tubercle of Zuckerkandl to develop, and differed slightly compared to radiographic methods. The majority of dm1 protoconid cuspal (occlusal region) enamel formed before birth. The dm2 entoconid enamel formed mainly after birth. Birth reduced daily enamel secretion rates, changed the visibility of incremental markings, and disrupted enamel growth for 3 to 8 days. Findings presented here can contribute to age-at-death estimates for human infants aged 13-postnatal months or less, and should facilitate comparisons of primate deciduous incremental enamel development in an evolutionary context. Regression equations are included so that cuspal formation time can be estimated from enamel thickness.
Two-dimensional patterns of human enamel thickness (2010). Archives of Oral Biology [Online] 55:115-126. Available at: http://dx.doi.org/10.1016/j.archoralbio.2009.11.014.
Objective: To characterise patterns of enamel thickness on deciduous (dm1, dm2) and permanent first (M1) mandibular molars and evaluate these against functional and morphological interpretative models.
Methods: Histological sections of mesial and distal cusps from 69 unworn molars were produced and examined using transmitted light microscopy. Enamel cap area, dentine area,as well as average and linear measurements of enamel thickness were recorded fromdigital images of the sections using image analysis software. Comparisons were made along the molar row, and between the mesial and distal sections of each tooth, using univariate and multivariate inferential statistics.
Results: The enamel cap area, dentine area, and average enamel thickness increased from the anterior to the posterior molars. The greatest proportional increase in linear enamel thickness occurred between the outside surface of the lingual cusps when dm1 was compared to dm2, and between the outside surface of the buccal cusps when dm2 was compared to M1. The enamel cap area increased from the mesial to the distal sections in M1. Dentine area decreased from the mesial to distal sections in dm1. Enamel cap and dentine areas did not change across dm2.
Conclusion: Results for the deciduous molars are interpreted within a functional model of mastication, in which the dm2 dissipates less laterally orientated loads compared to dm1. Differences in enamel thickness between dm2 and M1 support previous functional interpretations
for this permanent molar. Some mesial–distal results are not easily explained from either a functional or a morphological perspective and suggest an underlying developmental constraint.
Mahoney, P. (2008). Intraspecific variation in M1 enamel development in modern humans: implications for human evolution. Journal of Human Evolution [Online] 55:131-147. Available at: http://dx.doi.org/10.1016/j.jhevol.2008.02.004.
The timing and sequence of enamel development, as well as enamel thickness, was documented for individual cusps (protoconid, hypoconid,metaconid, entoconid) in 15 unworn permanent lower first molars (M1s) from a sample of modern human juveniles. These data were compared with previously published data for modern and fossil species reported in the literature.
Crown formation in all teeth was initiated in the protoconid and completed in the hypoconid. These cusps had significantly longer formation times (2.91 and 2.96 yrs, respectively) than the metaconid and entoconid (2.52 and 2.38 yrs, respectively), as well as thicker enamel, and each represented between 92e95% of the total crown formation time. Rates of enamel secretion in all cusps increased significantly from 2.97 mm in the inner enamel to 4.47 mm in the outer enamel. Two cusps of one individual were studied in more detail and did not follow this typical trajectory. Rather, there was a sharp decrease in the middle of enamel formation and then a slow recovery of secretion rates from the mid to outer enamel. This anomalous trajectory of enamel formation is discussed in the context of other nondental tissue responses to illness. Neither secretion rates nor periodicity differed significantly when compared between the cusps of each molar. Differences in cusp formation times, initiation, and completion suggest a relationship between the rates of enamel formation and enamel thickness. This fits with expectations about the mechanics of the chewing cycle and general lower molar morphology. A comparison with similar
data for some nonhuman primates and fossil hominoids suggests this relationship may hold true across several primate taxa. Other aspects of enamel growth differed between this human sample and certain fossil species. The lower molars formed slowly over a longer period of time,
which may reflect the extended growth period of modern humans. The methodological approach adopted in this study is discussed in the context of that used in other studies.
Mahoney, P., Smith, T., Schwartz, G., Dean, C. and Kelley, J. (2007). Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus indicus. Journal of Human Evolution [Online] 53:61-68. Available at: http://dx.doi.org/10.1016/j.jhevol.2007.01.007.
During the past decade, studies of enamel development have provided a broad temporal and geographic perspective on evolutionary devel- opmental biology in Miocene hominoids. Here we report some of the first data for molar crown development in one hominoid genus, Sivapi- thecus. The data are compared to a range of extant and extinct hominoids.
Crown formation times (CFTs), daily rates of enamel secretion (DSR), Retzius line number and periodicity, and relative enamel thickness (RET) were calculated in a mandibular first molar of Sivapithecus parvada and a maxillary first molar of Sivapithecus indicus from the Siwalik sequence of Pakistan. A CFT of 2.40 years for the protoconid of S. parvada and 2.25 years for the protocone of S. indicus lie within the range of first molar (M1) formation times for the majority of Miocene hominoids (1.96e2.40 years, excluding Proconsul heseloni), and are similar to an M1 from Gorilla (2.31 years) and M1s from Pan (2.22e2.39 years). This is unlike the longer CFTs in modern humans, which appear to be linked with their extended growth period. In contrast to extant great apes and humans, daily rates of enamel secretion are rapid in the Sivapithecus M1s during the early stages of growth, which seems to be a common pattern for most Miocene apes. The rapid accumulation of cuspal enamel in the Sivapithecus molars produced thicker enamel than either Pan or Gorilla in a comparable period of time. Future studies on larger samples of living and fossil hominoids are needed to clarify trends in crown development, which may be better understood in the context of life history strategies coupled with good data on body mass and brain size.
Mahoney, P. (2007). Human Dental Microwear From Ohalo II (22,500–23,500 cal BP), Southern Levant. American Journal of Physical Anthropology [Online] 132:481-500. Available at: http://onlinelibrary.wiley.com.chain.kent.ac.uk/doi/10.1002/ajpa.20548/abstract.
Dietary hardness and abrasiveness are inferred from human dental microwear at Ohalo II, a late Upper Palaeolithic site (22,500–23,500 cal BP) in the southern Levant. Casts of molar grinding facets from two human skeletons were examined with a scanning electron microscope. The size and frequency of microwear was measured, counted, and compared to four prehistoric human groups from successive chronological periods in the same region: pre-pottery Neolithic A, Chalcolithic (this study); Natufian, pre-pottery Neolithic B (Mahoney: Am J Phys Anthropol 130 (2006) 308–319). The Ohalo molars had a high frequency of long narrow scratches, and a few small pits, suggesting a tough abrasive diet that required more shearing rather than compressive force while chewing. These results imply that the diet of the two late Upper Palaeolithic hunter-gatherers did not focus on very hard foods. Aquatic foods with adherent contaminants, as well as grit from plant grinding tools seemed likely causal agents. The size of the pits and scratches on the Ohalo molars were most similar to microwear from the pre-pot- tery Neolithic A period, though they also compared well to the Chalcolithic period. These results contrasted with the larger pits and scratches from the Natufian hunter-gath- erers and pre-pottery Neolithic B farmers, implying that there is no simple increase or decrease in dietary hard- ness and abrasiveness across the late Upper Palaeolithic to Chalcolithic development in the Southern Levant.
Mahoney, P. (2006). Dental Microwear From Natufian Hunter-Gatherers and Early Neolithic Farmers: Comparisons Within and Between Samples. American Journal of Physical Anthropology [Online] 130:308-319. Available at: http://dx.doi.org/10.1002/ajpa.20311.
Microwear patterns from Natufian hunter-gatherers (12,500–10,250 bp) and early Neolithic (10,250–7,500 bp) farmers from northern Israel are correlated with location on facet nine and related to an archaeologically suggested change in food preparation. Casts of permanent second mandibular molars are examined with a scanning electron microscope at a magnification of 500×. Digitized micrographs are taken from the upper and lower part of facet nine. Microwear patterns are recorded with an image-analysis computer program and compared within and between samples, using univariate and multivariate analyses. Comparisons within samples reveal a greater frequency of pits on the lower part of the facet among the farmers, compared to the upper part. Microwear does not vary over the facet among the hunter-gatherers. Comparisons between samples reveal larger dental pits (length and width) and wider scratches among the farmers at the bottom of the facet, compared to the hunter-gatherers. Microwear does not vary between samples at the top of the facet. The microwear patterns suggest that the Natufian to early Neolithic development led to a harder diet, and this is related to an archaeologically suggested change in food processing. The harder diet of the early farmers may have required higher bite forces that were exerted at the bottom of facet nine, in the basin of the tooth.
Mahoney, P. (2006). Brief Communication: Intertooth and Intrafacet Dental Microwear Variation in an Archaeological Sample of Modern Humans From the Jordan Valley. American Journal of Physical Anthropology [Online] 129:39-44. Available at: http://dx.doi.org/10.1002/ajpa.20212.
Dental microwear was recorded in a Bronze-Iron Age (3570–3000 BP) sample of modern humans recovered from Tell es-Sa'idiyeh in the Jordan Valley. Microwear patterns were compared between mandibular molars, and between the upper and lower part of facet 9. The comparison revealed a greater frequency of pits and shorter scratches on the second and third molars, compared to the first. Pit frequency also increased on the lower part of the facet on the first molar, compared to the upper part. These results support previous calls for standardization when selecting a molar type for a diet-microwear study. Otherwise the microwear variations along the tooth row could mask any diet-microwear correlations. The results also suggest that there may be a need to choose a consistent location on a facet in order to enhance comparability among studies.
Miszkiewicz, J., Bennett, C., Johns, S. and Mahoney, P. (2016). Femoral bone remodeling comparisons between adult males and females from medieval England. In: The 85th Annual Meeting of the American Association of Physical Anthropologists.
Differences in bone metabolism between males and females in extant populations provide a basis from which to reconstruct gender divisions in labor for ancient humans. However, little is currently known about bone microstructure variation with sex in ancient English societies. Here, we access cortical bone remodeling using histological methods to compare males and females from the medieval period in Canterbury, England.
Following standard anthropological guidelines, sex and age-at-death were estimated for a total of 445 human skeletons, yielding 49 young and 180 middle-aged males, and 77 young and 139 middle-aged females. Static histomorphometry parameters were recorded in thin sections removed from the posterior femoral midshaft. Osteon population and osteocyte lacunae densities were compared between the sexes within each age category using univariate statistics.
Significantly higher remodeling was observed in males when compared to females. For example, osteon population density was higher in young (p = .044) and middle-aged (p. = .000) male groups when compared to females. Osteocyte lacunae were also denser (p = .001) in young males than females. Changes in cortical remodeling remained consistent when our analysis was adjusted for femoral robusticity to account for sexual dimorphism in bone size.
Our findings agree with bone physiology principles, and are congruous with previous histological studies of other archaeological populations. We link higher remodeling in males to greater mechanical loads. Medieval lifestyle differences that include gender specific labor divisions are inferred. Results are discussed in a hormonal bone physiology framework, and bone mass attainment variation with age and sex.
Mahoney, P., Miszkiewicz, J., Pitfield, R., Schlecht, S., Deter, C. and Guatelli-Steinberg, D. (2016). Biorhythms, deciduous enamel thickness, and primary bone growth in modern human children: a test of the Havers-Halberg Oscillation hypothesis. In: The 85th Annual Meeting of the American Association of Physical Anthropologists (2016). Wiley. Available at: http://meeting.physanth.org/program/2016/session12/mahoney-2016-biorhythms-deciduous-enamel-thickness-and-primary-bone-growth-in-modern-human-children-a-test-of-the-havers-halberg-oscillation-hypothesis.html.
Across mammalian species, the periodicity with which enamel layers form (Retzius periodicity) in permanent teeth corresponds with average body mass and the pace of life history. According to the Havers-Halberg Oscillation hypothesis (HHO), Retzius periodicity (RP) is a manifestation of a biorhythm that is also expressed in lamellar bone. Potentially, these links provide a basis for investigating aspects of a species’ biology from fossilized teeth. Here, we tested intra-specific predictions of this hypothesis on skeletal samples of modern human juveniles. We measured daily enamel growth increments to calculate RP in deciduous molars (n=25). Correlations were sought between RP, molar average enamel thickness (AET), and the average amount of primary bone growth in humeri from age-matched juveniles.
Results show a previously un-described relationship between RP and enamel thickness. Reduced major axis regression reveals RP is significantly and positively correlated with AET, and scales isometrically. The scaling relationship could not be explained through body mass. Juveniles with higher RPs and thicker enamel had more primary bone formation, which suggests a coordinating biorhythm. However, the direction of the correspondence was opposite to that predicted by the HHO. Next, we compared RP from deciduous molars to new data for permanent molars, and previously published values. The lowermost RP of four and five days in deciduous enamel was less than the lowermost value of six days in permanent enamel. A lowered range of RP values in deciduous enamel indicates that the underlying biorhythm might change with age. Our results develop the HHO.
Mahoney, P., Schmidt, C., Deter, C., Slavin, P. and Miszkiewicz, J. (2015). Social weaning: childhood diet and health in medieval Canterbury, UK. In: The 84th Annual Meeting of the American Association of Physical Anthropologists. WILEY-LISS, DIV JOHN WILEY & SONS INC, p. 1. Available at: http://meeting.physanth.org/program/2015/session14/mahoney-2015-social-weaning-childhood-diet-and-health-in-medieval-canterbury-uk.html.
Food consumption during the medieval period is understood mainly from adult diet, higher status families, and monastic communities. By contrast, there is little direct evidence for foods consumed by children, or whether their diet corresponded with health and status. Here, we address these questions in skeletal samples from the medieval city of Canterbury. We undertake the first comprehensive intra-specific microwear texture analysis of childhood diet (n=51) and integrate this with histological ‘snap-shots’ of general health from enamel accentuated markings (n=71). An adult comparative sample (n=11) is included.
Microwear texture complexity values increased from age 1 to 4yrs while anisotropy values decreased suggesting that foods became harder and required more varied jaw movements during chewing. The 4.1-6 year olds had a significantly lower mean complexity value than younger children. Complexity values increased again while anisotropy decreased in 6.1-9 year olds. Prevalence of accentuated markings peaked at 6 months, early in the second year, and just before age 4yrs. Diet did not relate to childhood status, and adults consumed a greater range of softer and harder foods.
Health of the youngest children likely relates to an immature immune system. Correspondence between a softer diet and improved health around age 4yrs may indicate the start of ‘social weaning’. Textual evidence refers to lifestyle changes from this age onwards, as children undertook household chores and then work outside the home. This might have provided less opportunity for early childhood dietary staples contaminated with grit, and initially introduced a softer but more nutritious adult food.
Mahoney, P., Schmidt, C., Deter, C., Remy, A., Slavin, P., Miszkiewicz, J. and Nystrom, P. (2015). Social weaning: childhood diet and health in medieval Canterbury, UK. In: The 84th Annual Meeting of the American Association of Physical Anthropologists (2015). Wiley, p. 1. Available at: http://meeting.physanth.org/program/2015/session14/mahoney-2015-social-weaning-childhood-diet-and-health-in-medieval-canterbury-uk.html.
Food consumption during the medieval period is understood mainly from adult diet, higher status families, and monastic communities. By contrast, there is little direct evidence for foods consumed by children, or whether their diet corresponded with health and status. Here, we address these questions in skeletal samples from the medieval city of Canterbury. We undertake the first comprehensive intra-specific microwear texture analysis of childhood diet (n=51) and integrate this with histological ‘snap-shots’ of general health from enamel accentuated markings (n=71). An adult comparative sample (n=11) is included. Microwear texture complexity values increased from age 1 to 4yrs while anisotropy values decreased suggesting that foods became harder and required more varied jaw movements during chewing. The 4.1-6 year olds had a significantly lower mean complexity value than younger children. Complexity values increased again while anisotropy decreased in 6.1-9 year olds. Prevalence of accentuated markings peaked at 6 months, early in the second year, and just before age 4yrs. Diet did not relate to childhood status, and adults consumed a greater range of softer and harder foods. Health of the youngest children likely relates to an immature immune system. Correspondence between a softer diet and improved health around age 4yrs may indicate the start of ‘social weaning’. Textual evidence refers to lifestyle changes from this age onwards, as children undertook household chores and then work outside the home. This might have provided less opportunity for early childhood dietary staples contaminated with grit, and initially introduced a softer but more nutritious adult food.
Mahoney, P. (2014). The trajectory of human prenatal enamel growth slows through the trimesters. In: 83rd Annual Meeting of the Ammerican Association of Physical Anthropologists. WILEY-LISS, DIV JOHN WILEY & SONS INC. Available at: http://onlinelibrary.wiley.com/doi/10.1002/ajpa.v153.S58/issuetoc.
Typically, human fetal growth rates change
through the trimesters depending on the tissue
type. Linear growth in long bones peaks in the
second trimester and increases in fetal weight are
greatest in the third. Human deciduous tooth
enamel starts to develop at different times in
utero, commencing with the central incisor and
lastly with the second molar. But whether the
trajectory of prenatal enamel growth remains the
same for each tooth type is poorly understood.
Here, I use histological methods to determine
how long it takes a 250?m (in 25?m increments)
thick layer of prenatal enamel to form in
maxillary incisors, canines, and molars (n=88). I
also calculate prenatal extension rates to assess
how quickly these teeth grow in height. I relate
the trajectory of growth in thickness and height
to the trimesters. Findings are tested on
mandibular lateral incisors and second molars
Results show that the growth trajectory
changes through the trimesters. Incisor enamel
initiated early in the second trimester and 250?m
formed over 52-57 days. Canines and second
molars initiated closer to birth and required 60-
64 days to form the same depth of enamel.
Although initial extension rates were positively
correlated with crown height within each tooth
class (incisors, r=0.714; molars, r=0.676), they
were significantly greater (p<0.005) in incisors
when compared to the taller canines and second
molars. These findings provide evidence that
initial prenatal enamel growth is faster in incisors
than all other deciduous tooth types. I infer this
is related to their early postnatal eruption.
Miszkiewicz, J. and Mahoney, P. (2014). Histological variation in modern human robust and gracile femur. In: The 83rd Annual Meeting of the American Association of Physical Anthropologists (2014). Wiley, p. 187. Available at: http://meeting.physanth.org/program/2014/session49/miszkiewicz-2014-histological-variation-in-modern-human-robust-and-gracile-femur.html.
Bones respond to mechanical stimuli by altering their internal and external structure. Bioarchaeologists routinely use this knowledge to infer ancient human behaviour. However, the extent to which human bone robusticity reflects its microstructural properties is still largely unexplored. Here, histological variation was examined in an archaeological sample of adult human femora (n = 450) dating to the medieval period in the UK.
Femoral midshaft circumference (Mid.C) and posterior cortical thickness (Post.Cort.T) were recorded and used to create five robusticity groups. Histological sections from the posterior aspect of each femur were prepared following standard methods. Osteon population density (OPD), Haversian canal area (H.Ar) and diameter (H.Dm), osteon area (On.Ar) and osteocyte lacunae density (Ot.Dn) were compared between the groups.
Histology values differed significantly between the five robusticity groups, though variation with age and between sexes was not consistent. A multivariate discriminant function analysis revealed that Ot.Dn, On.Ar, Ot.Dn, and H.Dm were the best predictors of Mid.C and Post.Cort.T in each of the five groups.
Results indicate increased remodeling activity in larger and thicker bone. Small osteons and Haversian canals imply a highly strenuous loading history in robust femora. It is suggested that studies which infer ancient human behaviour from comparisons of femoral bone microstructure should account for histological variation that occurs with increased bone robusticity.
Miszkiewicz, J. and Mahoney, P. (2013). Paleohistopathology of a Harris line. In: The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013). Wiley, p. 200. Available at: http://meeting.physanth.org/program/2013/session28/miszkiewicz-2013-paleohistopathology-of-a-harris-line.html.
Identification of Harris lines (HLs), a non-specific indicator of bone growth disruption, is usually achieved radiographically. Histological methods have only been implemented to explore the underlying processes of HL formation in longitudinal sections of animal bone. No prior study has examined HL histopathology in a human skeletal specimen. Here, a first insight into HL formation, from transverse sections in a human distal tibia, is provided. Results will aid understanding about the nature of HL, and its identification from histology.
Distinct HLs were identified macroscopically, and from a radiograph, in a left distal tibia taken from an adult male dating to the British Medieval period. Multiple transverse sections were taken through the HL, and also from trabecular bone regions located immediately proximal and distal to the HL. Thin sections of undecalcified bone were produced following standard histological procedures. Slides were examined under a high-powered microscope at 20x, 40x, and 60x using polarized light. Images were captured using a digital microscope camera and imaging software, and later assembled into montages.
Trabeculae proximal and distal to the HL exhibited no abnormal growth, displaying numerous osteocyte lacunae and a healthy lamellar structure. However, the microanatomy of the HL was characterised by three main features: 1) non-lamellar appearance, 2) lack of osteocyte lacunae, 3) presence of irregular bundle-like canals oriented in multiple directions. These histopathological features indicate an abnormal manner of bone deposition, implying that trapping of osteoblasts does not take place during HL formation. Pictorial and descriptive records of tibial HL histopathology are provided.
Miszkiewicz, J. and Mahoney, P. (2012). Bone microstructure and behaviour in “gracile” and “robust” adult males from the Medieval Period, Canterbury, UK. In: The 81st Annual Meeting of the American Association of Physical Anthropologists (2012). Wiley, pp. 215-216. Available at: http://dx.doi.org/10.1002/ajpa.22033.
ifferent types of activity can affect the morphology and strength of limb bones. This bone functional adaptation means that aspects of behaviour can be inferred in archaeological samples of modern humans. One popular methodological approach is to examine muscle attachment sites. However, this technique can be subjective. An alternative approach is to analyze bone microstructure. This latter method is more objective, because histological units directly linked to bone growth can be quantified. Here, we seek differences in bone microstructure between twenty age-matched adult ‘robust’ and ‘gracile’ male skeletons dated to the British Medieval period.
Samples were selected based upon gross skeletal morphometry (37 bilateral postcranial measurements), muscle markers (55 bilateral postcranial sites), and femoral midshaft cross-section cortical thickness. Samples were then assigned as either ‘robust’ (n=10) or gracile (n=10). Following this, standard histological procedures were employed to produce thin sections of the posterior (P), anterior (A), lateral (L), and medial (M) femoral midshaft. Eight microscopic variables were compared between the groups.
Intact osteon density (P:p=.013), fragmentary osteon density (P and M:p=.002, L:p=.010), osteon population density (P:p=.002, M:p=.003), Haversian canal area (A:p=.016, P:p=.028, M:p=.005, L:p=.002), Haversian canal diameter (A:p=.010, P:p=.023, M:p=.002, L:p=.007), osteon area (A:p=.002, P:p=.034, M:p=.001, L:p=.010), and osteocyte lacunae density (A:p=.011, P:p=.006, M and L:p=.000) differed significantly between gracile and robust males. Results indicate faster remodelling rates in robust individuals. Differences in behaviour are inferred between the two groups. A more active lifestyle involving excessive leg muscle use is inferred for the robust male group. Methodological suggestions are given.
Miszkiewicz, J. and Mahoney, P. (2011). Linear enamel hypoplasia at medieval Canterbury, UK. In: 80th Annual Meeting of the American Association of Physical Anthropologists. Wiley, p. 218. Available at: http://dx.doi.org/10.1002/ajpa.21502.