Variation in δ(13) C and δ(15) N values can be assessed to understand not only diet, but also the influence of physiological factors on an individual. The metabolic balance of an individual can impact isotopic signals in tissues that are forming during the periods of metabolic stress. Fluctuating δ(15) N values are associated with physiological stressors that alter an individual's metabolism such as infection, injury, or pregnancy. This study examines variation in δ(13) C and δ(15) N values along sequentially segmented hair in both modern and archaeological individuals. Subjects with an observable skeletal pathology, known chronic illness, or evidence of pregnancy were compared with controls exhibiting no evidence of physiological stress. The results on hair samples from individuals from 19(th) century Belleville, Ontario, four modern cadavers (two with cancer and two sudden deaths), and two living pregnant women indicate that δ(15) N values are approximately 1‰ higher in individuals with a pathological condition (e.g., infection, fracture, or cancer) and are 1‰ lower during pregnancy, whereas δ(13) C values show less variability. Higher nitrogen values may represent the recycling of nitrogen derived from the breakdown of existing proteins in the body (catabolism), whereas lower δ(15) N values are related to increased utilization of dietary and urea nitrogen for tissue synthesis during pregnancy. These findings suggest that short-term fluctuations of δ(15) N values may be the result of changes in an individual's metabolic balance, and that metabolic imbalance poses a confounding factor to ancient dietary studies when using rapidly growing tissues such as hair.

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Objectives: With a growing interest in the mother-infant dyad and the Developmental Origins of Health and Disease hypothesis among biological and medical anthropologists, this study set out to provide all the information required to evaluate if mineralization defects in dentine might be caused by vitamin D deficiency in the critical first 1000 days of life.Materials and Methods: Information was compiled on dentine formation in utero to approximately 18 years, and a method for determining the location of the neonatal line in dentine was devised, allowing the assessment of the prenatal and early life period. Reevaluation of previously analyzed teeth (n = 61) was undertaken with detailed examination of n = 5/22 first permanent molars forming in the prenatal and critical early life periods.Results: First permanent molars and all deciduous teeth give information on intrauterine development and on the first 1000 days postnatally providing a direct window on maternal and fetal health. Three archaeological individuals had interglobular dentine that formed prenatally suggesting that their mothers experienced vitamin D deficiency at the time dentine was forming and all other individuals had a deficiency during the first 1000 days of life. Conditions that could cause systemic mineralization defects were determined, and in each, case they were found to be consistent with vitamin D deficiency.Discussion: The neonatal line serves as a clear baseline for determining prenatal and postnatal events, particularly those related to vitamin D, calcium, and phosphate metabolism, and can be used to investigate the maternal-infant dyad for both past and present communities. K E Y W O R D S interglobular dentine, maternal health, neonatal line, prenatal vitamin D deficiency 1 | INTRODUCTION Teeth provide a permanent biological marker of metabolic stressors that disrupt mineralization in utero and early childhood. This is signifi-cant for both medical and biological anthropologists interested in the mother-infant dyad and the Developmental Origins of Health and Disease hypothesis (DOHaD), offering insights into maternal health and a means by which theoretical approaches linked to early life conditions that affect development can be tested and developed. DOHaD is a paradigm that explores how early life environments, particularly Megan B. Brickley and Lori D'Ortenzio contributed equally to this study.

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Objectives This study investigates vitamin D deficiency patterns in individuals from birth to the beginning of adolescence. Microscopic computed tomography (micro‐CT) evaluation of interglobular dentine (IGD) in teeth provides information on the age of disease onset and the number of deficient periods per individual, which will increase our understanding of factors influencing vitamin D deficiency prevalence, including sociocultural practices and latitude. Materials and methods Beemster and Hattem, two Dutch 17th–19th century communities, yielded relatively high prevalences of rickets (15–24%) and residual rickets (15–24%). From the affected individuals, a subsample of 20 teeth were selected for micro‐CT scanning. Thin sections were made of 17 teeth, consisting of 6 teeth with and 11 teeth without observable IGD on micro‐CT that were included for method comparison. Results About 19 out of 29 (65.5%) individuals (one tooth was deemed unobservable) presented with IGD on micro‐CT. Eight of the 11 (72.7%) individuals without IGD on micro‐CT demonstrated histologically visible IGD. In 40.7% (11/27) of the affected individuals (combined micro‐CT and histology results), vitamin D deficiency was recurrent, and in four individuals, some episodes occurred at approximately annual intervals suggesting vitamin D deficiency was seasonal. In three individuals, IGD occurred in the dentine formed around birth, suggesting maternal vitamin D deficiency. Discussion Micro‐CT analysis of IGD is found to be a valuable non‐destructive method that can improve our understanding of the influence of sociocultural practices and latitude on disease development within age and sex groups in past communities.