Objectives Studies of the carbon and nitrogen stable isotope ratios (δ13C and δ15N) of modern tissues with a fast turnover, such as hair and fingernails, have established the relationship between these values in mothers and their infants during breastfeeding and weaning. Using collagen from high-resolution dentine sections of teeth which form in the perinatal period we investigate the relationship between diet and physiology in this pivotal stage of life. Materials and Methods Childhood dentine collagen δ13C and δ15N profiles were produced from horizontal sections of permanent and deciduous teeth following the direction of development. These were from two 19th-century sites (n = 24) and a small number (n = 5) of prehistoric samples from Great Britain and Ireland. Results These high-resolution data exhibit marked differences between those who survived childhood and those who did not, the former varying little and the latter fluctuating widely. Discussion Breastfeeding and weaning behavior have a significant impact on the morbidity and mortality of infants and the adults they become. In the absence of documentary evidence, archaeological studies of bone collagen of adults and juveniles have been used to infer the prevalence and duration of breastfeeding. These interpretations rely on certain assumptions about the relationship between isotope ratios in the bone collagen of the adult females and the infants who have died. The data from this study suggest a more complex situation than previously proposed and the potential for a new approach to the study of maternal and infant health in past populations.

Yes / The major components of human diet both past and present may be estimated by measuring the carbon and nitrogen isotope ratios (δ13C and δ15N) of the collagenous proteins in bone and tooth dentine. However, the results from these two tissues differ substantially: bone collagen records a multi-year average whilst primary dentine records and retains timebound isotope ratios deriving from the period of tooth development. Recent studies harnessing a sub-annual temporal sampling resolution have shed new light on the individual dietary histories of our ancestors by identifying unexpected radical short-term dietary changes, the duration of breastfeeding and migration where dietary change occurs, and by raising questions regarding factors other than diet that may impact on δ13C and δ15N values. Here we show that the dentine δ13C and δ15N profiles of workhouse inmates dating from the Great Irish Famine of the 19th century not only record the expected dietary change from C3 potatoes to C4 maize, but when used together they also document prolonged nutritional and other physiological stress resulting from insufficient sustenance. In the adults, the influence of the maize-based diet is seen in the δ13C difference between dentine (formed in childhood) and rib (representing an average from the last few years of life). The demonstrated effects of stress on the δ13C and δ15N values will have an impact on the interpretations of diet in past populations even in slow-turnover tissues such as compact bone. This technique also has applicability in the investigation of modern children subject to nutritional distress where hair and nails are unavailable or do not record an adequate period of time. / This study was supported by an Arts and Humanities Research Council grant funding to JB under AHRC Studentship AH/I503307/1.

Yes / Sampling of dentine for stable carbon (δ13 C) and nitrogen (δ15 N) isotope ratios in the direction of tooth growth allows the study of temporal changes to the diet and physiological stress of an individual during tooth formation. Current methods of sampling permanent teeth using 1mm increments provide temporal resolution of six - nine months at best depending on the tooth chosen. While this gives sufficient sample sizes for reliable analysis by mass spectrometry, sectioning the dentine across the incremental structures results in a rolling average of the isotope ratios. A novel method of incremental dentine collagen sampling has been developed to decrease the collagen increment size to 0.35mm along the incremental structures thus reducing averaging and improving the temporal resolution of short-term changes within the δ13 C and δ15 N values. This study presents data for a MicroMill-assisted sampling method that allows for sampling at 0.35mm width x 1mm depth increments following the incremental growth pattern of dentine. A NewWave MicroMill was used to sample the demineralised dentine section of modern donated human third molars from Sudan and compared to data from the same teeth using the 1mm incremental sectioning method 2 from Beaumont et al. (2013). The δ13 C and δ15 N isotopic data showed an increased temporal resolution, with each increment providing data for two-four months of dentine formation. The data show the potential of this method for studying dietary reconstruction, nutritional stress, and physiological change with greater temporal resolution potentially to seasonal level and with less attenuation of the δ13 C and δ15 N values than was previously possible from human dentine.

Sampling methods for dentine and bone collagen have been evolving for several decades. Incremental dentine collagen sampling and bone collagen sampling have been limited by the available technology throughout that time. As the technology for isotope ratio mass spectrometry analysis improves, the sampling methods should improve as well. This research focused on developing a new incremental dentine collagen sampling method and bone collagen microsampling method for stable isotope analysis. This research aimed to increase the temporal resolution of incremental dentine collagen sampling and provided sequential collagen sampling from bone collagen for stable carbon and nitrogen isotope analysis while limiting the destructive nature of bioarchaeological analysis. It was determined that the temporal resolution for incremental analysis could be reduced to approximate three months, opposed to the nine months found in other sampling methods. It was also determined that detailed isotopic data could be obtained from bone collagen when sampling the microstructures. The increased amount of isotopic data from the bone collagen was an improvement on the commonly used bulk collagen sampling. This research can be utilised to answer several of the questions that archaeologists have been asking about past populations. Isotopic analysis using the methods developed in the research can provide a more detailed observation of the diet and health of past populations. In addition, the developed methods for bone and dentine collagen reduced the amount of tissue subjected to destructive analysis.