scholarly journals Developmental stress in South African hominins: Comparison of recurrent enamel hypoplasias in Australopithecus africanus and Homo naledi

2019 ◽  
Vol 115 (5/6) ◽  
Author(s):  
Mark F. Skinner
Keyword(s):  
South African ◽  
Geographical Area ◽  
Developmental Stress ◽  
Enamel Hypoplasia ◽  
Enamel Defects ◽  
Australopithecus Africanus ◽  
Anterior Teeth ◽  
Equatorial Africa ◽  
Linear Enamel Hypoplasia ◽  
Digital Microscope

Discovery of a new hominin (Homo naledi) in the same geographical area as Australopithecus africanus creates the opportunity to compare developmental dental stress in higher latitude hominins with low that in latitude apes, among whom repetitive linear enamel hypoplasia (rLEH) recurs seasonally at about 6 or 12 months. In contrast to equatorial Africa, a single rainy/dry cycle occurs annually in non-coastal southern Africa. It is predicted that LEH will recur annually but not differ in duration between ancient and more recent hominins. Data were collected from epoxy casts of anterior teeth attributed to H. naledi (18 incisors, 13 canines) and A. africanus (29 incisors, 8 canines) using a digital microscope, surface scanner and scanning electron microscope. The location, number, width, depth and distance between defects (including perikymata counts and spatial measurements) of 136 LEH events were compared among crown moieties (deciles 4–6 and 7–9), tooth types and taxa. Enamel defects are concentrated in the cervical half of anterior crowns, and in similar numbers in each taxon. Contrary to expectations, H. naledi show bimodal LEH durations reconstructed at about 2 and 8 weeks compared to just 4 weeks in A. africanus. Both taxa show bimodally recurrent episodes of LEH centring on 2 and, more commonly and severely, 6 months. A combination of two independent annual stressor types, one disease and one seasonal, could explain the observations. These estimations of duration and recurrence of developmental stress require evaluation using actual perikymata periodicity for H. naledi and more refined understanding of palaeoenvironments for both taxa. Significance: Seasonal stress is a central concern in the biological and health sciences. Because of the innate way that enamel is deposited, the timing of stress in the childhood of apes, modern humans and their fossil ancestors can be measured with a precision of about 1 week. Application of this method to South African Pliocene Australopithecus africanus and Mid-Pleistocene Homo naledi reveals that, unexpectedly, both forms show semi-annual stress – a finding that is tentatively attributed to two independent annual stressors, possibly disease and malnutrition.

scholarly journals Root grooves on two adjacent anterior teeth of Australopithecus africanus

2017 ◽  
Author(s):  
Ian Towle ◽  
Joel D. Irish ◽  
Marina Elliott ◽  
Isabelle De Groote
Keyword(s):  
South African ◽  
Root Surface ◽  
Dental Erosion ◽  
Tissue Loss ◽  
Cervical Lesions ◽  
Dental Tissue ◽  
Australopithecus Africanus ◽  
Food Items ◽  
Anterior Teeth ◽  
Fossil Hominin

AbstractTooth root grooves and other ante-mortem dental tissue loss not associated with caries found on or near the cementoenamel junction (CEJ) are commonly termed non-carious cervical lesions. Three main processes are implicated in forming these lesions: abrasion, dental erosion, and abfraction. As yet, these lesions have not been described in non-Homo hominins. In this study South African fossil hominin collections were examined for evidence of any type of non-carious cervical lesion. Only one individual shows ante-mortem root grooves consistent with non-carious cervical lesions. Two teeth, a mandibular right permanent lateral incisor (STW 270) and canine (STW 213), belonging to the same Australopithecus africanus individual, show clear ante-mortem grooves on the labial root surface. These lesions start below the CEJ, extend over a third of the way toward the apex, and taper to a point towards the lingual side. Microscopic examination revealed no clear directional striations. The shape of these grooves is extremely similar to clinical examples of dental erosion, with the lack of striations supporting this diagnosis. These are the oldest hominin examples of non-carious cervical lesions and first described in a genus other than Homo; further, the lesions suggest that this individual regularly consumed or processed acidic food items.

Dental Modifications of Anterior Teeth in the Danish Viking Age

2017 ◽  
Author(s):  
Verner Alexandersen ◽  
Niels Lynnerup
Keyword(s):  
Viking Age ◽  
Enamel Hypoplasia ◽  
Anterior Teeth ◽  
Linear Enamel Hypoplasia

Inspired by previous finds of filed, likely ornamental grooves on upper incisors of Swedish and Danish male Vikings, a Viking sample from Denmark (ca. AD 800–1050) was studied (M=69, F=45, 90=?). We found evidence of modifications that could be distinguished from normal wear and linear enamel hypoplasia. In 24 individuals single or multiple filed horizontal grooves occurred on labial surfaces of the central upper incisors and some lateral incisors (22/159 or 13.8 percent). All grooves were inconspicuous and shallow, and other unrelated worn labial facets were found. This occurrence is unlike the grooves in male Swedish Vikings. The variation observed, as well as experiments with iron files and whetstones, leads us to suggest that the Danish Viking grooves could be made intentionally but more often developed as a result of task activities. 

Can linear enamel hypoplasia be used as a novel welfare indicator in pigs?

2007 ◽  
Vol 2007 ◽  
pp. 40-40
Author(s):  
E. Genever ◽  
K. Dobney ◽  
D.M. Broom
Keyword(s):  
Stressful Life Event ◽  
Stressful Events ◽  
Environmental Stressors ◽  
Developmental Stress ◽  
Enamel Hypoplasia ◽  
Linear Enamel Hypoplasia ◽  
Welfare Indicator ◽  
Calcified Tissue ◽  
The Individual ◽  
Incremental Lines

Linear enamel hypoplasia (LEH) produces abnormal incremental lines or depressions in teeth enamel caused by a deficiency in the growth of calcified tissue. The depth and width of the LEH events can indicate the severity and duration of a stressful life event. LEH can be used to investigate developmental stress, as it will occur when the individual is unable to cope with environmental stressors during development, such as food shortage, pathological challenge or other stressful events. The LEH technique has been used by zoo-archaeologists to obtain information on early domestication and husbandry practices in ancient populations of pigs, where high levels of LEH have been found to correspond to birth and weaning. The objective of this work was to investigate if LEH was present in modern pigs and whether it could be used as a welfare indicator.

scholarly journals Stress, sex, and plague: patterns of developmental stress and survival in pre- and post-Black Death London

2019 ◽  
Author(s):  
Sharon DeWitte
Keyword(s):  
Pubertal Timing ◽  
Temporal Trends ◽  
Black Death ◽  
Developmental Stress ◽  
Enamel Hypoplasia ◽  
Chi Square ◽  
Stress Markers ◽  
Kaplan Meier ◽  
Linear Enamel Hypoplasia ◽  
Before And After

OBJECTIVES: Previous research revealed declines in survivorship in London before the Black Death (c. 1346-1353), and improvements in survivorship following the epidemic. These trends indicate that there were declines in general levels of health before the Black Death and improvements thereof afterwards. This study expands on previous research by examining whether changes in survivorship were consistent between the sexes, and how patterns of developmental stress markers changed before and after the Black Death.MATERIALS AND METHODS: This study uses samples from London cemeteries dated to one of three periods: Early Pre-Black Death (1000-1200 AD, n = 255), Late Pre-Black Death (1200-1250 AD, n = 247), or Post-Black Death (1350-1540 AD n = 329). Temporal trends in survivorship are assessed via Kaplan-Meier survival analysis, and trends in tibial length (as a proxy for stature) and linear enamel hypoplasia (LEH) are assessed using t-tests and Chi-square tests, respectively.RESULTS: Survivorship for both sexes decreased before the Black Death and increased afterwards. For males, LEH frequencies increased and stature decreased before the epidemic, and LEH declined and stature increased after the Black Death. For females, the only significant change with respect to developmental stress markers was a decrease in stature after the Black Death.CONCLUSIONS: These results might reflect variation between the sexes in sensitivity to stressors, the effects of nutrition on pubertal timing, disproportionate access to dietary resources for males in the aftermath of the Black Death, the disproportionate deaths of frail individuals during the epidemic, or some combination of these factors.

scholarly journals An Interdisciplinary Approach for Rehabilitating a Patient with Amelogenesis Imperfecta: A Case Report

2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
Niloufar Khodaeian ◽  
Mahmoud Sabouhi ◽  
Ebrahim Ataei
Keyword(s):  
Case Report ◽  
Interdisciplinary Approach ◽  
Amelogenesis Imperfecta ◽  
Clinical Report ◽  
Enamel Hypoplasia ◽  
Oral Rehabilitation ◽  
Developmental Defects ◽  
Posterior Teeth ◽  
Enamel Defects ◽  
Anterior Teeth

Amelogenesis imperfecta (AI) has been defined as a group of hereditary enamel defects. It can be characterized by enamel hypoplasia, hypomaturation, or hypocalcification of the teeth. AI may be associated with some other dental and skeletal developmental defects. Restoration for patients with this condition should be oriented toward the functional and esthetic rehabilitation. This clinical report describes the oral rehabilitation of a young patient diagnosed with the hypoplastic type of AI in posterior teeth and hypomatured type of AI in anterior teeth.

scholarly journals An examination of the differential susceptibility pattern of the dentition to linear enamel hypoplasia

COMPASS ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 54-69
Author(s):  
Jennifer S Nelson
Keyword(s):  
Cultural Practices ◽  
Tooth Development ◽  
Physiological Stress ◽  
Differential Susceptibility ◽  
Susceptibility Pattern ◽  
Enamel Hypoplasia ◽  
Differential Distribution ◽  
Anterior Teeth ◽  
Dental Pathology ◽  
Linear Enamel Hypoplasia

Enamel hypoplasia is a dental pathology that forms when an individual is exposed to physiological stress in early life while tooth crowns are developing. Biological anthropologists utilize these enamel defects as indicators of growth interruption and interpret them as reflective of factors pertaining to health status and cultural practices that influence health. Over decades of research, numerous studies have noted a pattern in the distribution of linear enamel hypoplasia across the dentition. It is suggested that the anterior dentition presents the highest frequency of defects, followed by the premolars, with molars most rarely exhibiting hypoplasia. This apparent differential susceptibility pattern has resulted in the preferential study of the anterior dentition in anthropology, however little research has been conducted into the validity or cause of this developmental phenomenon. Through examination of the literature, the observed higher frequency of enam2el hypoplasia in the anterior dentition substantiates the existence of this differential distribution pattern. Further investigation reveals that the cause of this varying susceptibility has not been sufficiently explored, leading to a number of inconclusive explanations. Examination of these theories – ranging from the chronology of tooth development, specifics of crown morphology, and variations in genetic control – indicate that there is no single causal variable, but that a multitude of factors are responsible. From this research it is apparent that further study is necessary to fully understand why the anterior teeth appear to be more susceptible to hypoplastic defects than their posterior counterparts.

scholarly journals Enamel Hypoplasia Related to Historical Famine Stress in the Contemporary Chinese Population

2018 ◽  
Vol 11 (2) ◽  
pp. 3-5
Author(s):  
Liming Zhou ◽  
Robert S. Corruccini
Keyword(s):  
Rural Communities ◽  
Chinese Population ◽  
Physiological Stress ◽  
Population Level ◽  
Causal Link ◽  
Developmental Stress ◽  
Enamel Hypoplasia ◽  
Enamel Formation ◽  
Linear Enamel Hypoplasia ◽  
Contemporary Chinese

Linear enamel hypoplasia (LEH), a defect in enamel formation, has been frequently attributed to malnutrition and other physiological stress during periods of enamel development (Sarnat and Schour, 1941; Kreshover, 1960). LEH has been widely used as an indicator of developmental stress in skeletal studies among historic and prehistoric populations (Goodman et al., 1980; Corruccini et al., 1985; Goodman and Rose, 1990). A study of 3,014 subjects in 26 birth-year cohorts, samples from urban and rural communities of China, indicated that significant differences in LEH frequencies occurred between persons whose teeth developed during the famine years (1959-1961) and those whoe teeth calcified during non-famine years. This result points to a causal link between enamel hypoplasia and childhood nutritional stress at the population level, and casts some light on the magnitude and effects of the little-documented Chinese famine. 

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