Gender and Population Variation in Craniometry and Freehand Pass Ventriculostomy.

BACKGROUND: Ventriculostomy using the freehand pass method is subject to complications arising from misplacement of the catheter tip. This method may require multiple passes for successful catheterization. Methods of determining the burr-hole location (known as the Kocher point) were derived historically from European patients and may not be appropriate for other populations with different cranial shapes. This study examines the possibility that anatomic variation in interpopulation variation together with sexual dimorphism in cranial size and shape may contribute to this problem. METHODS: Sagittal and parasagittal measurements of the frontal bone were taken of 300 Thai (150 female, 150 male) crania and 300 American white (150 female, 150 male) crania. These measurements were compared to determine sexual dimorphism and interpopulation variation in size and shape. RESULTS: The measurements were statistically significantly larger in males than in females and on the right side than the left in both sexes in both Thai and American white samples. The frontal bone is significantly longer at the sagittal plane in Europeans of both sexes than in Thai, but in the parasagittal plane, there is no difference. This finding indicates a difference in frontal bone shape between the 2 populations and between males and females. CONCLUSIONS: The dimensions of the frontal bone vary between males and females and can vary among populations. The optimal location for the burr hole in freehand pass ventriculostomy may depend on both the gender and the ancestry of the patient.

A large modern Southeast Asian human skeletal collection from Thailand.

The Khon Kaen University Human Skeleton Research Centre has a large human collection consisting of 745 modern northeastern Thai (Isan) skeletons derived from bodies bequeathed to the Department of Anatomy during the period 1979-2014. The aim of this paper is to document the collection and address the question of whether the collection may be representative of local Isan people, or populations of the wider region of mainland Southeast Asia. This will determine its value as a reference collection for forensic anthropology in particular but also for all other fields of research about human skeletal biology. Sex is recorded for 99.6% of the skeletons, and age at death for 91.7%. The collection consists of two-thirds males, one-third females. It includes 10 individuals less than 19 years of age, and adults ranging in age from 20 to 109 years of age. Average age at death is 62 years. Other data available for smaller proportions of the collection include cause of death, occupation, and height and weight at the time of donation. Dates of birth are estimated to range from the late 19th Century to the most recent in 1988. Analysis of the demographic composition of the collection shows that is likely to be representative of the ancestral mix of the Isan people, and of the village farmers who still form a large portion of the Isan population. It may also represent 20th Century populations of much of Southeast Asia where agriculture dominates the economy. The collection forms a valuable resource for research on regional human skeletal characteristics for use in forensic anthropology.

Using isotopic evidence to assess the impact of migration and the two-layer hypothesis in prehistoric Northeast Thailand.

OBJECTIVES: The nature of the agricultural transition in Southeast Asia has been a topic of some debate for archaeologists over the past decades. A prominent model, known as the two-layer hypothesis, states that indigenous hunter-gatherers were subsumed by the expansion of exotic Neolithic farmers into the area around 2000 BC. These farmers had ultimate origins in East Asia and brought rice and millet agriculture. Ban Non Wat is one of the few archaeological sites in Southeast Asia where this model can potentially be tested. The site is located in the Mun River valley of Northeast Thailand, and divided into 12 phases that span over 2,000 years, from about 1750 BC to the end of the Iron Age (ca. 500 AD). These phases exhibit successive cultural changes, and current interpretation of the site is of an early hunter-gatherer population, with agriculturalists immigrating into the later phases. METHODS: We analyzed strontium, oxygen, and carbon isotopes in tooth enamel from over 150 individuals, dating from the Neolithic to Iron Age, to assess extrinsic origins and differences in diet between early and later phases. RESULTS: We find evidence of dietary and cultural differences between groups at Ban Non Wat during its early occupation, but little evidence for immigration from distinct environments beyond the Khorat Plateau of Northeast Thailand. CONCLUSIONS: The lack of consistent isotopic differences between early and later Neolithic occupants at Ban Non Wat means that the site does not conclusively support the two-layer hypothesis.

Assessing Raman spectroscopy as a prescreening tool for the selection of archaeological bone for stable isotopic analysis.

Stable isotope analyses for paleodiet investigations require good preservation of bone protein, the collagen, to obtain reliable stable isotope values. Burial environments cause diagenetic alterations to collagen, especially in the leaching of the organic bone content. The survival of bone protein may be assessed by the weight % collagen, % carbon and % nitrogen yields, but these values are achieved only after destructive chemical processing. A non-destructive method of determining whether bone is suitably preserved would be desirable, as it would be less costly than chemical processing, and would also preserve skeletal collections. Raman analysis is one such potential non-destructive screening method. In previous applications, Raman spectroscopy has been used to test both the alteration of the mineral portion of bone, as well as to indicate the relative amount of organic material within the bone structure. However, there has been no research to test the relationship between the Raman spectroscopic results and the survival of bone protein. We use a set of 41 bone samples from the prehistoric archaeological site of Ban Non Wat, Northeast Thailand, to assess if Raman spectroscopy analysis of the organic-phosphate ratio has a significant correlation with the weight % collagen, and carbon and nitrogen yields obtained by isotopic analysis. The correlation coefficients are highly statistically significant in all cases (r = 0.716 for collagen, r = 0.630 for carbon and r = 0.706 for nitrogen, p≤0.001 for all) with approximately or close to half of the variation in each explained by variation in the organic-phosphate ratio (51.2% for collagen, 39.6% for carbon, and 49.8% for nitrogen). Although the Raman screening method cannot directly quantify the extent of collagen survival, it could be of use in the selection of bone most likely to have viable protein required for reliable results from stable isotope analysis.

Aspects of health in prehistoric mainland Southeast Asia: Indicators of stress in response to the intensification of rice agriculture.

Numerous bioarcheological investigations have suggested that as agriculture intensifies, levels of physiological stress and poor health increase. However, previous research in Southeast Asia suggests that a decline in health was not universal. This study aimed to provide the first investigation of human health during the intensification of rice agriculture in the large skeletal sample from the prehistoric site of Ban Non Wat, Northeast Thailand (1750-420 b.c.). Health was analysed using two indicators of childhood stress, the prevalence of linear enamel hypoplasia (LEH), a measure of early childhood stress, and stature, as a measure of late childhood stress, were collated for 190 adults. Sex-specific diachronic relationships between the prevalence of LEH and stature were explored. For both sexes, initially the prevalence of LEH was found to decrease and then increase over time. Stature remained constant over time for males, although for females stature increased initially, then decreased. Early childhood stress was not significantly correlated with stature in females (P = 0.185), but high levels of LEH were unexpectedly correlated with taller male stature (P = 0.017). Our findings suggest an initial improvement in health during agricultural intensification at this site, likely related to a reduction in physiological perturbations and maintenance of a nutritious diet during this time. The subsequent deterioration in health may reflect geomorphologically and archaeologically indicated variation in environmental conditions and consequential sociocultural changes. We suggest that the sex-differences in the relationship between stature and LEH may relate to the timing of stress and/or catch-up growth.

Is it health or the burial environment: differentiating between hypomineralised and post-mortem stained enamel in an archaeological context.

Developmental enamel defects are often used as indicators of general health in past archaeological populations. However, it can be difficult to macroscopically distinguish subtle hypomineralised opacities from post-mortem staining, unrelated to developmental defects. To overcome this difficulty, we have used non-destructive x-ray microtomography to estimate the mineral density of enamel. Using a sample of deciduous teeth from a prehistoric burial site in Northeast Thailand, we demonstrate that it is possible to determine whether observed enamel discolourations were more likely to be true hypomineralised lesions or artefacts occurring as the result of taphonomic effects. The analyses of our sample showed no evidence of hypomineralised areas in teeth with macroscopic discolouration, which had previously been thought, on the basis of macroscopic observation, to be hypomineralisations indicative of growth disruption. Our results demonstrate that x-ray microtomography can be a powerful, non-destructive method for the investigation of the presence and severity of hypomineralisation, and that diagnosis of enamel hypomineralisation based on macroscopic observation of buried teeth should be made with caution. This method makes it possible to identify true dental defects that are indicative of growth disruptions.

The first New Zealanders: patterns of diet and mobility revealed through isotope analysis.

Direct evidence of the environmental impact of human colonization and subsequent human adaptational responses to new environments is extremely rare anywhere in the world. New Zealand was the last Polynesian island group to be settled by humans, who arrived around the end of the 13th century AD. Little is known about the nature of human adaptation and mobility during the initial phase of colonization. We report the results of the isotopic analysis (carbon, nitrogen and strontium) of the oldest prehistoric skeletons discovered in New Zealand to assess diet and migration patterns. The isotope data show that the culturally distinctive burials, Group 1, had similar diets and childhood origins, supporting the assertion that this group was distinct from Group 2/3 and may have been part of the initial colonizing population at the site. The Group 2/3 individuals displayed highly variable diets and likely lived in different regions of the country before their burial at Wairau Bar, supporting the archaeological evidence that people were highly mobile in New Zealand since the initial phase of human settlement.