Island rule and bone metabolism in fossil murines from Timor

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 might 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 (~5000–18 000 years old). Femur morphometric data were used in computing phylogenetically informed body mass regressions, although the phylogenetic signal was very low (Pagel’s λ = 0.03). Estimates of body weight calculated from these femora ranged from 75 to 1188 g. Osteocyte lacunae densities from histological sections of the midshaft femur were evaluated against bone size and estimated body weight. Statistically significant (P < 0.05) and strongly negative relationships between Ot.Dn, femur size and estimated weight were found. Larger specimens were characterized by lower Ot.Dn, indicating that giant murines from Timor might have had a relatively slow pace of bone metabolic activity, consistent with predictions made by the island rule

Cortical histomorphometry of the human humerus during ontogeny

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

Chapter 2. Skeletal health in Medieval societies: insights from stable isotopes and dental histology

With social and economic systems determining the structure and function of human groups come health repercussions that affect our longevity and quality of life. Consequently, skeletal disorders in the modern world are becoming increasingly problematic as populations experience ageing-driven changes in bone metabolism. Coupled with often poor quality nutrition and largely sedentary lifestyles, skeletal adaptation in contemporary populations is facing more challenges than ever before. As biological anthropologists attempt to understand the interwoven biological and cultural relationships influencing the ways in which we grow and adapt to our environments, the medical realm tackles bone fragility and fracture risk at a patient and society level. Human lifestyle as a research theme appears to unite bio-anthropological and medical queries into bone health