[Show abstract][Hide abstract] ABSTRACT: Enamel hypoplasias are useful indicators of systemic growth disturbances during childhood, and are routinely used to investigate patterns of morbidity and mortality in past populations. This study examined the pattern of linear enamel hypoplasias in two different burial populations from 18th and 19th Century church crypts in London. Linear enamel hypoplasias on the permanent dentitions of individuals from the crypt of Christ Church, Spitalfields, were compared to enamel defects on the teeth of individuals from St. Bride's. The method used involves the identification of enamel defects at a microscopic level, and systemic perturbations are detected by matching hypoplasias among different tooth classes within each individual. The pattern of linear enamel hypoplasias was contrasted between individuals from the burial sites of Spitalfields and St. Bride's, between males and females, and between those aged less than 20 years of age and those aged over 20 years at death. Six different parameters were examined: frequency of linear enamel hypoplasias, interval between defects, duration of hypoplasias, age at first occurrence of hypoplasia, age at last occurrence of hypoplasia, and the percentage of enamel formation time taken up by growth disturbances. All individuals in the study displayed linear enamel hypoplasias, with up to 33% of total visible enamel formation time affected by growth disruptions. Multiple regression analysis indicated a number of significant differences in the pattern of enamel hypoplasias. Individuals from Spitalfields had shorter intervals between defects and greater percentages of enamel formation time affected by growth disturbances than did individuals from St. Bride's. Females had greater numbers of linear enamel hypoplasias, shorter intervals between defects, and greater percentages of enamel formation time affected by growth disturbances than males. There were also differences in the pattern of enamel hypoplasias and age at death in this study. Individuals who died younger in life had an earlier age at first occurrence of enamel hypoplasia than those who survived to an older age. The pattern of enamel hypoplasias detected in this study was influenced by tooth crown geometry and tooth wear such that most defects were found in the midcrown and cervical regions of the teeth, and greater numbers of defects were identified on the anterior teeth. Differences in sensitivity of the parameters used for the detection of enamel hypoplasias were found in this study. The percentage of visible enamel formation time affected by growth disturbances was the parameter that identified the greatest number of significant differences among the subgroups examined.
American Journal of Physical Anthropology 12/2005; 128(3):547-59. · 2.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Developmental disturbances that affect the secretion of enamel matrix can cause defective enamel structure. Linear hypoplasia is one type of enamel defect and manifests itself as a furrow that runs around the circumference of the tooth. Such defects range in size from the microscopic to those that are several millimetres wide. Enamel defects have been widely used by anthropologists for the investigation of growth disruptions in past populations, as they provide a permanent record of disturbances during much of a child's developmental period. This is a detailed case study of enamel growth disruptions in a 15-year-old female from the 18th and 19th century crypt of Christ Church, Spitalfields. The method used relates linear enamel hypoplasia to the incremental structures in the enamel surface, the perikymata, in order to investigate the timing of growth disturbances. Linear enamel hypoplasia was defined here as a greater than expected spacing between neighbouring pairs of perikymata. In addition, this study used recently published histological data on the precise timing of tooth development to establish chronologies for growth disruptions. Defects were matched in at least two teeth with overlapping developmental schedules to ensure that systemic disturbances, as opposed to localised traumas, were identified. Thirteen enamel defects were matched between five different teeth from the same individual from Spitalfields. Most linear enamel hypoplasias were evident on the anterior dentition. Using an 8-day average perikymata periodicity, the age at first defect in this individual was calculated as 1.5 years and the last growth disruption occurred when she was 4.6 years of age. The distribution of the defects was examined to identify any seasonal pattern in the occurrence of the growth disturbances.
Archives of Oral Biology 02/2002; 47(1):29-39. · 1.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Taphonomic processes have the potential to affect microscopic wear on teeth and to modify the wear patterns so as to confound dietary reconstructions based on dental microwear which was formed during the lifetime of an animal. This study describes a series of experiments which were conducted to simulate various taphonomic agents and to record their effect on dental microwear. Three types of experiment were carried out in order to explain anomalous microscopic wear that had been found on the dentition of several hominoid specimens from the 15 M.a. site of Pasalar in Turkey. The effect of two different acids-citric and hydrochloric acid-on dental microwear was investigated. Modification to microscopic wear caused by alkali (carbonatite ash) was examined in the second set of experiments. Lastly, the effect of abrasion by three different size classes of sediment from the site of Pasalar-quartz pebbles (grain size varied from 2,000-11,000 microm), coarse sand (grain size ranged from 500-1,000 microm), and medium-sized sand (grain diameters were between 250 and 500 microm)-was investigated. Results confirm previous findings that the taphonomic modification of dental microwear is readily identifiable and causes the obliteration rather than secondary alteration of microwear features. The experiments show that both citric and hydrochloric acid affect dental microwear but to varying degrees, whereas alkali did not cause any modification of microscopic features. The different size classes of sediment also had different effects on the dental microwear. The largest size sediment (quartz pebbles) polished the enamel and removed finer microwear features. The coarse sand, however, did not have any effect on the microwear. The greatest amount of abrasion was caused by the smallest sediment particles -the medium-sized sand. Several hominoid dental specimens from Pasalar display similar microscopic wear to the two types of acid erosion and the abrasion caused by the medium-sized sands.
American Journal of Physical Anthropology 04/1999; 108(3):359-73. · 2.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The examination of microscopic dental wear allows inferences to be made about diet in extinct species. This study reconstructs the diet of Griphopithecus alpani, a 15 Ma fossil hominoid from the Miocene site of Paşalar in north-western Turkey, using scanning electron microscopy (SEM) to examine the microscopic wear on its molar teeth. The microwear patterns of Griphopithecus are compared with those of three extant hominoid taxa-Gorilla gorilla gorilla, Pan troglodytes verus, and Pongo pygmaeus pygmaeus. The microwear on three occlusal wear surfaces is examined in this study, and sex and age differences are also included. Analysis of variance is performed on the following microwear variables-feature density, pit density, striation density, the ratio of pits relative to striations, pit widths, and striation widths. Griphopithecus has significantly higher microwear feature densities and higher percentages of pits than Gorilla. It also has larger pit frequencies and narrower striations than both Pan and Gorilla. There are no significant differences between the microwear patterns of Griphopithecus and Pongo. This suggests that the diet of Gripho-pithecus was more similar to that of Pongo, which consumes mainly fruit, and occasionally hard and unripe fruits and nuts, than to that of Pan and Gorilla. In addition, the high percentage of pits displayed by Griphopithecus may indicate that it was ingesting harder fruits and/or objects than the extant hominoids, although this is not a significant difference. There also are consistent variations in the microwear present on the three different wear facets examined in the study-Phase II facets display more microwear and pitting than the Phase I surface examined. The results of this study do not indicate variation in dental microwear according to sex or age.
Journal of Human Evolution 02/1999; 36(1):3-31. · 3.87 Impact Factor