A Comparison of Metric and Nonmetric Techniques Used in the Classification of Hispanic Crania
- by Ben Thompson and Donna C. Boyd (Dept. of Anthropological Sciences, Forensic Science Institute, Radford University)
(Source: submitted by author)
A Comparison of Metric and Nonmetric Techniques Used in the Classification of Hispanic Crania
(Source: submitted by author)
"Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured-light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal–buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r2 5 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV 5 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces” (read more/not open access).
(Source: American Journal of Physical Anthropology 152:186-196, 2013)
- by Lara K. Noldner and Heather J.H. Edgar
"This comparison of methods for assessing the development of muscle insertion sites, or entheses, suggests that three-dimensional (3D) quantification of enthesis morphology can produce a picture of habitual muscle use patterns in a past population that is similar to one produced by ordinal scores for describing enthesis morphology. Upper limb skeletal elements (humeri, radii, and ulnae) from a sample of 24 middle-aged adult males from the Pottery Mound site in New Mexico were analyzed for both fibrous and fibrocartilaginous enthesis development with three different methods: ordinal scores, two-dimensional (2D) area measurements, and 3D surface areas. The methods were compared using tests for asymmetry and correlations among variables in each quantitative data set. 2D representations of enthesis area did not agree as closely as ordinal scores and 3D surface areas did regarding which entheses were significantly asymmetrical. There was significant correlation between 3D and 2D data, but correlation coefficients were not consistently high. Intraobserver error was also assessed for the 3D method. Cronbach’s alpha values fell between 0.68 and 0.73, and error rates for all entheses fell between 10% and 15%. Marginally acceptable intraobserver error and the analytic versatility of 3D images encourage further investigation of using 3D scanning technology for quantifying enthesis development” (read more/not open access).
(Source: American Journal of Physical Anthropology 152:417-424, 2013)
Okay, so I have a LOT of feelings about conclusions drawn from enthesis evaluation given I do pathology and I see huge differences in enthesis development that are more related to being a bone-former than anything actually having to do with muscles. I also appreciated the caveats in this paper. That said, the subject is one of my favorites. I also recommend this paper (open access!) even though it isn’t about humans:
It is about basically using a smaller version of the Large Hadron Collider for shooting incredibly excited electrons at bones, after all, and that’s awesome.
This is the scientific tangle that is part of my PhD, and I’m partially on all sides…
Also, shouldn’t we define what we mean by a “bone former” before stating it as an aetiological factor? Not all bone forming is necessarily pathological!
You’re right, and being a a “bone former” (Ortner quotes Rogers et al. 1997 in defining this as “an individual with increased potential to create reactive bone” on page 547 of Identification of Pathological Conditions in Human Skeletal Remains) is not necessarily a pathological condition. As I’ve come across it in my research, it’s a confusing part of not finding a pathological condition in a skeleton that looks DISH-y but doesn’t have DISH (entire skeletal involvement, lots of extra bone formation, some candle-wax vertebrae but not in a DISH pattern and with no vertebral fusion) - I describe what I see and kind of shrug and say “might be a bone former.” I also have the luxury of behavioral and veterinary records taken in life for my skeletons, so I can ask the researchers if they ever observed that gorilla behaving as if she was bothered by arthritis, and the answer is usually no for the possible bone-formers I bring to them (unless I’m asking about a gorilla of advanced age who probably also had osteoarthritis - it’s a tangle!). They tend to have particularly rugose muscle attachments and lots of enthesophytes, even if they weren’t particularly large, heavily-muscled gorillas. (Another wrinkle: who knows if what is true for gorillas is true for humans.) I wasn’t saying the paper was bunk - I actually like it a lot. I also wasn’t saying that all rugose muscle attachments are due to genetic predisposition to bone-forming. It’s just that I do get tired of the assumption that large muscle attachment always equals large, heavily-used muscle (researchers who have one bone out of an entire skeleton and scream “occupational marker!” I’m looking at you), and prefer that it is kept in mind that biological creatures are always so freaking complicated when we’re making conclusions about what we see.
tl;dr I bet our thoughts about this issue are pretty similar, but feel free to correct me if I’m wrong.
I love this discussion.
“Dental enamel hypoplasia is usually read as a sign of a systematic growth disturbance during childhood. Following the analysis of human teeth from Herculaneum (79 AD, Central Italy), the authors focused on linear enamel hypoplasia (LEH) manifestations in order to delineate a possible correlation between their frequency and distribution and the earthquake that occurred in 62 AD, which is well documented in historical literature. The human remains from Herculaneum were buried at the same time as the Vesuvius eruption and represent an exceptional snapshot of life in the Roman Imperial Age. The Goodman and Rose method (1990) was used for attributing an “age at the moment of stress” for every skeleton in order to delineate the epidemiology of the enamel hypoplasia. When LEH frequency was analysed by age, two different age groups showed relevant patterns of hypoplasia: the first peak was evident in individuals between 14 and 20 years who were younger than 6 years at the time of the 62 AD earthquake, and a second peak was noted in adults of 30 ± 5 years old, which suggests the presence of another stressful event that occurred 10 years before the earthquake, around 53 AD. The bimodal distribution of enamel hypoplasia could be the consequence of two different historical periods characterized by instability in the food supply, unhygienic conditions, and epidemic episodes; our data suggest that the first peak could be related to a decline in health status as an effect of the 62 AD earthquake. The relationship between recent natural disasters and variations in health status in modern populations is well documented in scientific literature. Our research represents the first attempt to correlate the status of health to an earthquake of known date in an archaeological population” (read more/open access).
“Sex estimation of skeletal remains with satisfactory allocation accuracy represents an essential step in reconstructing the biological profile of unknown individuals in archaeological research and forensic practice. Teeth are among the most frequently recovered physical elements of an individual that remain after death due to their hardness, durability, and resistance to postmortem insults. This study was based on the deciduous and permanent dentition of 269 individuals (150 males and 119 females) from the Granada osteological collection of identified infants, young children, and adults (Granada, Spain). Mesiodistal, buccolingual, and diagonal crown and cervical diameters of both dentitions were measured, and logistic regression analyses were performed to create equations for sex discrimination. The results show that the first and second deciduous molars and the permanent canines are the teeth with the greatest sexual dimorphism, providing percentages of correct assignment of sex between 78.1 and 93.1% in deciduous dentition and between 79.4 and 92.6% in permanent teeth, depending on the dimensions used. The results indicate that this method may be applicable as an adjunct with other accepted procedures for sex estimation when fragmentary skeletal remains are encountered in archaeological excavations and in forensic contexts” (read more/open access).
(Open access source: American Journal of Physical Anthropology 152:31-43, 2013 via Academia.edu)
“A number of new works concerning the Moravian Upper Palaeolithic have appeared over the last thirteen years. This thematic review presents an overview of Upper Palaeolithic excavations conducted in the third millennium in Moravia and all major works on this topic. The review is structured chronologically, it begins with the Middle to Upper Palaeolithic transition (technocomplexes of Szeletian and Bohunician), continues with Early Upper Palaeolithic (Aurignacian) and Middle Upper Palaeolithic (Gravettian or Pavlovian) and ends with the Late Upper Palaeolithic (technocomplexes of Epigravettian and Magdalenian). The works which are not connected with any particular period, such as papers discussing raw materials, settlement strategies, regional overviews of the Palaeolithic settlement or synthesis, are mentioned in the last chapter. The main aim of this thematic review is to present recent results of research into the Moravian Upper Palaeolithic to a foreign audience” (read more/open access).
(Open access source: Interdisciplinaria Archaeologica, Natural Sciences in Archaeology 4(2), 2013 via Academia.edu)
“The skeletal remains of an adult female have been exhumed in an 11th century tomb in the mediaeval Jewish cemetery of Ronda Sur, in the city of Lucena (Córdoba, Spain). Examination of the skull and mandible revealed evidences of bilateral condylar fracture and dislocation. Lesions were observed macroscopically and radiology was used as a complementary method of scrutiny, especially in cases of unclear observation. Irregular morphology of the condyles and coronoid processes, shallow glenoid fossa, altered and abnormal joint surfaces anterior to the glenoid fossa, and reduced height of both ascending rami were observed. Ante-mortem tooth loss, slight wear of occlusal surface and asymmetrical occlusal deposit of dental calculus were found. Radiologically, degenerative changes in the condyles and reparative bone in both coronoid processes have been identified. Dislocation of the condyles and lack of adequate treatment probably led to disruption of masticatory patterns and related structures, such as muscle attachments, articular disc and ligaments. Bilateral remodelled fracture and the altered appearance of the joint structures could probably mean that the individual survived the injury by several years. This type of fracture could be the consequence of direct blow to the mental or submental region that was transmitted in a direction that raised the mandible, causing the condylar head to collide directly with the mandibular fossa. Very few mandibular fractures in ancient skulls have been described in Spain, and this case is the first example found in a Spanish archaeological skeletal assemblage” (read more/open access).
(Open access source: International Journal of Osteoarchaeology 23:485-504, 2013 via Academia.edu)
“The earliest euprimates to arrive in North America were larger-bodied notharctids and smaller-bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small- and increasingly mid-sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P4 displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P4 can also provide important paleoecological insights. We analyzed the P4 from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two-dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P4 than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P4 disparity and convergent evolution of the semimolariform condition in the largest omomyines. P4 morphology relates to diet in early euprimates, although patterns vary between families” (read more/open access).
(Open access source: American Journal of Physical Anthropology 153:15-28, 2014)
Human evolutionary biology and Palaeolithic archaeology
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