Technical note: Enhancement of Scott's molar wear scoring method

A method is described for orienting maxillary and mandibular molars in order to standardize the reporting of wear scores on quadrants of the occlusal surfaces (Scott: Am J Phys Anthropol 51 (1979) 213–217). The method, which was developed on an archeological sample from ancient Mendes, Egypt, further requires that quadrant scores be reported individually and sequentially for each tooth, rather than summed, in order to identify more easily differential and directional wear patterns. Intraobserver and interobserver error was found to be negligible when the appropriate diagrams and instructions were consulted. Thus, observer error does not add further to the potential for error associated with Scott's original scoring method. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Technical note: A blind test of mandibular ramus flexure as a morphologic indicator of sexual dimorphism in the human skeleton

Loth and Henneberg (1996, Am. J. Phys. Anthropol. 99:473–487) identified a single morphological feature of the mandible, the presence or absence of a distinct flexure or angulation of the posterior margin of the mandibular ramus at the level of the occlusal plane, which appears to be an extraordinarily accurate predictor of sex. Using only this feature, Loth and Henneberg were able to predict sex with 94% accuracy in a large sample of mandibles. In this article, we report the results of a blind test of mandibular ramus flexure as a predictor of sex. In our blind test, only 62.5% of the mandibles were correctly sexed, and virtually identical results were obtained when the same sample of mandibles was examined by a second observer. Overall, our results demonstrate that: 1) the association between ramus flexure and sex is weak; 2) the predictive accuracy of Loth and Henneberg's method is better than chance for only one sex, males; and 3) the method is based on a trait that cannot be reliably or consistently identified. Am J Phys Anthropol 107:363–366, 1998 © 1998 Wiley-Liss, Inc.     

Deciduous dental morphology of the prehistoric Jomon people of Japan: Comparison of nonmetric characters

Morphological variations of the deciduous dentition are as useful as those of the permanent dentition for determining the biological affinities of human populations. This paper provides material on morphological variations of deciduous teeth of the prehistoric Japanese population from the Late and the Latest Jomon Period (ca. 2000–ca. 300 B.C.). The expression of nonmetric traits of the deciduous teeth in the Jomon sample shows a closer affinity with modern Japanese and Native American samples than with American White, Asiatic Indian, and African samples. However, the frequency of shoveling in deciduous upper incisors in the Jomon sample is lower than those in modern Japanese and Native American samples. The Jomon sample also expresses a much higher frequency of cusp 6 in deciduous lower second molars than seen in modern Japanese, Ainu, and Native American samples. The frequency in the Jomon sample is equal to that in the Australian Aboriginal sample, which shows cusp 6 most frequently among the samples compared. A somewhat low incidence of incisor shoveling in the Jomon sample was also reported in the permanent dentition (Turner [1976] Science 193:911–913, [1979] Am. J. Phys. Anthropol. 51:619–635, [1987] Am. J. Phys. Anthropol. 73:305–321, [1990] Am. J. Phys. Anthropol. 82:295–317; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:163–182, 88:183–196). However, the frequency of cusp 6 in the Jomon sample shows no significant difference from those of Northeast Asian or Native American samples in the permanent dentition (Turner [1987] Am. J. Phys. Anthropol. 73:305–321; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:1–182, 88:183–196). Evidently, some nonmetric traits express an inter-group difference only in the deciduous dentition. © 1995 Wiley-Liss, Inc.     

Morphology of the pubis and preauricular area in relation to parity and age at death in Macaca mulatta

Some adult human females show bone resorption (pitting) at the dorsal aspect of the pubis and preauricular area of the ilium. The etiology of pelvic bone resorption is attributed alternatively to reproduction and to pelvic anatomy. While most researchers infer that pelvic pitting is related to reproduction, only a few studies are based on women of known parity. Degree of pubic resorption is directly associated with both parity (Suchey et al.: Am. J. Phys. Anthropol. 51:517-539, 1979; Bergfelder and Hermann: J. Hum. Evol. 9:611-613, 1980) and age (Suchey et al.: Am. J. Phys. Anthropol. 51:517-539, 1979). The relationship between parity and degree of resorption of the preauricular area is equivocal, found to be significant by Dunlap (A Study of the Preauricular Sulcus in a Cadaver Population, Ph.D. dissertation, East Lansing, Michigan State University, 1981) but not by Spring et al. (Am. J. Phys. Anthropol. 79:247-252, 1989); both studies report that age is not associated with resorption of the preauricular area. Other mammals evidence public resorption, but the morphology of the preauricular area is less well known. This study addresses the issue on the etiology of pelvic bone resorption using a sample of Macaca mulatta (the free-ranging population from Cayo Santiago) for which parity and age at death are known for all specimens. The following results are reported. Resorption of the pubis is common among females but infrequent among males. Contrary to Rawlins (Am. J. Phys. Anthropol. 42:477-488, 1975), the degree of pubic resorption in female macaques is significantly related to both parity and age at death.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brief communication: Paleohistopathological analysis of pathology museum specimens: Can periosteal reaction microstructure explain lesion etiology?

The assertion that the microstructure of periosteal new bone formation can be used to differentiate between disease etiologies (Schultz: Yrbk Phys Anthropol 44 2001 106–147; Schultz: Identification of pathological conditions in human skeletal remains, 2nd ed. London: Academic Press 2003 73–109) was tested in a pilot‐study, using diagnosed bone specimens from St George's Hospital Pathology Museum, London, UK. Embedded bone specimens exhibiting pathological periosteal new bone formation were examined using scanning electron microscopy in back‐scattered electron imaging mode (SEM‐BSE). The results suggest that several histological features (i.e. Grenzstreifen, Polsters, and sinuous lacunae) deemed to be diagnostic of specific pathological conditions are of no specific diagnostic value, as they are encountered in pathological conditions of differing disease etiology. These results tie in with a previous investigation demonstrating a lack of diagnostic qualitative or quantitative characteristics seen in the macroscopic and radiographic appearance of periosteal reactions (Weston: Am J Phys Anthropol 137 2008 48–59). Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

The form of the supraorbital margin as a criterion in identification of sex from the skull: Investigations based on modern human skulls

Sexual dimorphism in the shape of the supraorbital margin was reported by Broca and various subsequent authors, but no consistently applied, precise definition has been established. In this study of modern human skulls, the value of our definition of the sex-related difference in this area in the identification of sex from the skull was investigated. It was found that this feature can be assessed reliably, is strongly related to sex, and is independent of the side. The accuracy of identification of sex using this method alone was found to be about 70%. Am J Phys Anthropol 108:91–96, 1999. © 1999 Wiley-Liss, Inc.     

Comparative locomotion and habitat use of six monkeys in the Tai Forest,Ivory Coast

The relationships between locomotion, body size, and habitat use in six sympatric Old World monkeys are examined to test whether the associations found are consistent with those demonstrated in previous studies (Fleagle and Mittermeier [1980] Am. J. Phys. Anthropol. 52:301–314; Gebo and Chapman [1995] Am. J. Phys. Anthropol. 97:49–76). Colobus polykomos, C. badius, C. verus, Cercopithecus diana, C. campbelli, and Cercocebus atys were studied for 14 months in the Ivory Coast's Tai Forest. Analyses reveal that (1) larger monkeys tend to frequent those strata containing the greatest densities of large supports while smaller monkeys are more diverse in their canopy use; (2) high frequencies of leaping are not necessarily confined to the understory, and understory specialists are not necessarily frequent leapers; (3) body size does not consistently predict leaping or climbing frequencies; (4) in general, climbing is more frequent during foraging and leaping is more common during travel; (5) larger supports are used during travel while smaller supports are used during foraging; and (6) larger monkeys do not always use larger supports than do smaller monkeys. Some of the factors contributing to the manner that locomotion, body size, and habitat use are related in cercopithecid monkeys are discussed. Am J Phys Anthropol 105:493–510, 1998. © 1998 Wiley-Liss, Inc.     

Sexing potential of fragmentary and pathological metacarpals

The use of metacarpal dimensions for determining skeletal sex is investigated. Previous studies on sexual dimorphism in the metacarpals (Scheuer and Elkington [1993]; J. Forensic Sci. 38:769–778; Falsetti [1995]; J. Forensic Sci. 40:774–776; Smith [1996]; J. Forensic Sci. 41:469–477) used multiple variables, which limits the application potential of the methodology. Using six measurements for each metacarpal, I generated 35 linear discriminant functions based on expected taphonomic or pathological preservation scenarios. The number of variables per function ranged from 2–5. Normal, jackknifed, and cross-validation classification matrices indicated a sex prediction accuracy in the 79–85% range. MC4 produced the most consistent functions. Overall accuracy in the validation samples ranged from 75–90%. ANOVA and MANOVA analyses indicated that population effects are insignificant, which may allow for the application of the functions without knowledge of the ancestral background of the individual. This, combined with the variety of preservation scenarios considered, provides accurate sex estimators for incomplete individuals. However, the population specificity of the insignificant population group effects remains untested. Am J Phys Anthropol 109:245–252, 1999. © 1999 Wiley-Liss, Inc.     

A quantitative and qualitative reanalysis of the endocast from the juvenile Paranthropus specimen l338y-6 from Omo, Ethiopia

Based on an analysis of its endocast, Holloway (1981 Am J Phys Anthropol 53:109-118) attributed the juvenile Omo L338y-6 specimen to Australopithecus africanus (i.e., gracile australopithecines) rather than to Paranthropus (Australopithecus) boisei (robust australopithecines) favored by other workers (Rak and Howell [1978] Am J Phys Anthropol 48:345-366). Holloway's attribution was based on the specimen's (1) low cranial capacity, (2) gracile-like meningeal vessels, (3) gracile-like cerebellar hemispheres, and (4) absence of an enlarged occipital/marginal (O/M) sinus system. Recent work, however, has shown that criteria 1 and 2 are not useful for sorting gracile from robust australopithecines (Culotta [1999] Science 284:1109-1111; Falk [1993] Am J Phys Anthropol 92:81-98). In this paper, we test criterion 3 by quantifying the endocranial cerebellar and occipital morphology reproduced on the Omo L338y-6 endocast, and comparing it to seven endocasts from South and East African early hominids. Our preliminary results show that metric analysis of this specimen cannot be used to sort it preferentially with either robust or gracile australopithecines. Finally, we demonstrate that, contrary to previous reports, the Omo L338y-6 endocast reproduces an enlarged left occipital sinus (criterion 4). This observation is consistent with the original attribution of the Omo specimen to robust australopithecines (Rak and Howell [1978] Am J Phys Anthropol 48:345-366). Furthermore, if Omo L338y-6 was a robust australopithecine, this discovery extends the occurrence of an enlarged O/M sinus system to one of the earliest known paranthropines. Am J Phys Anthropol 110:399-406, 1999.     

Incidence and distribution of postcranial fractures in the prehistoric population of San Pedro de Atacama,northern Chile

Trauma incidence analysis in skeletal populations has been very popular among skeletal biologists during the last two decades. In this context, the work of Lovejoy and Heiple ([1981] Am. J. Phys. Anthropol. 55:529–541) has been quoted as a landmark because their analysis rested on a populational approach, avoiding simple assumptions about cause and etiology. In this study, we apply to the prehistoric population of San Pedro de Atacama, northern Chile, an approach similar to that carried out by Lovejoy and Heiple (1981). The results obtained point to a peak of risk of fractures among old people, estimated age around 45 years. The distribution of fractures by sex and age suggests that the prevailing etiology is related to accidents and not violence. When the frequencies of fractures are compared, the Libben population shows a much higher incidence than the Atacamenean population. It is suggested that this difference can be explained by peculiarities of the subsistence economies of the two populations. Am J Phys Anthropol 109:253–258, 1999. © 1999 Wiley-Liss, Inc.     

Brief communication: Evaluating grandmother effects

Women who have outlived child‐bearing have long been described as postreproductive. But contributions they make to the survival or fertility of their descendants enhance the reproduction of their genes. Consequently, natural selection affects this characteristic stage of human life history. Grandmother effects can be measured in data sets that include births and deaths over several generations, but unmeasured covariates complicate the task. Here we focus on two complications: cohort shifts in mortality and fertility, and maternal age at death. We use the Utah Population Database to show that longevity of grandmothers may be associated with fewer grandchildren, as reported by Madrigal and Melendez‐Obando (Am J Phys Anthropol 136 (2008) 223–229) for a Costa Rican sample, even when grandmother effects are actually positive. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.     

Canine tip wear in male and female anthropoids

One component of the “dual selection hypothesis” (Greenfield [1992a] Year. Phys. Anthropol. 35:153–185) is that the tips of female canines are commonly blunted and more frequently so than those of conspecific males. Data derived from two randomly selected age-graded samples of Macaca fascicularis (n = 70) and Colobus badius (n = 59) show that at least 80% of the females exhibit tip blunting on one or both canines and that frequencies of blunting are far greater than those of conspecific males in both jaws. Sexual dimorphism in mandibular canine morphology and wear and other recently critiqued aspects of the “dual selection hypothesis” (Plavcan and Kelley [1996] Am. J. Phys. Anthropol. 99:379–387.) are also discussed. Am J Phys Anthropol 107:87–97. © 1998 Wiley-Liss, Inc.     

Stature estimation in ancient Egyptians: a new technique based on anatomical reconstruction of stature

Trotter and Gleser's (Trotter and Gleser: Am J Phys Anthropol 10 (1952) 469-514; Trotter and Gleser: Am J Phys Anthropol 16 (1958) 79-123) long bone formulae for US Blacks or derivations thereof (Robins and Shute: Hum Evol 1 (1986) 313-324) have been previously used to estimate the stature of ancient Egyptians. However, limb length to stature proportions differ between human populations; consequently, the most accurate mathematical stature estimates will be obtained when the population being examined is as similar as possible in proportions to the population used to create the equations. The purpose of this study was to create new stature regression formulae based on direct reconstructions of stature in ancient Egyptians and assess their accuracy in comparison to other stature estimation methods. We also compare Egyptian body proportions to those of modern American Blacks and Whites. Living stature estimates were derived using a revised Fully anatomical method (Raxter et al.: Am J Phys Anthropol 130 (2006) 374-384). Long bone stature regression equations were then derived for each sex. Our results confirm that, although ancient Egyptians are closer in body proportion to modern American Blacks than they are to American Whites, proportions in Blacks and Egyptians are not identical. The newly generated Egyptian-based stature regression formulae have standard errors of estimate of 1.9-4.2 cm. All mean directional differences are less than 0.4% compared to anatomically estimated stature, while results using previous formulae are more variable, with mean directional biases varying between 0.2% and 1.1%, tibial and radial estimates being the most biased. There is no evidence for significant variation in proportions among temporal or social groupings; thus, the new formulae may be broadly applicable to ancient Egyptian remains.     

Technical note: evaluating mandibular ramus flexure as a morphological indicator of sex

Described as a highly reliable method of sex identification, mandibular ramus flexure is a morphological trait expressed on the posterior border of the ramus at the occlusal plane (Loth and Henneberg [1996] Am. J. Phys. Anthropol. 99:473-485). In a blind test, 158 mandibles were examined for the presence of flexure as defined by Loth and Henneberg, resulting in 79.1% accuracy, which is well below the reported 91-99% accuracy. Twenty-five of these mandibles were assigned the ambiguous score of 0, an outcome of a +1 score for one side, and a -1 score for the other. Seventeen mandibles were examined twice to measure intraobserver error. Only 64.7% of the scores were duplicated in the second session, suggesting difficulty in consistent identification of flexure. Low overall accuracy, an invalid scoring system, and high intraobserver error indicate that mandibular ramus flexure is an unreliable technique for estimation of sex.     

Evaluation of the suchey–brooks method of age estimation in an Australian subpopulation using computed tomography of the pubic symphyseal surface

Despite the prominent use of the Suchey–Brooks (S–B) method of age estimation in forensic anthropological practice, it is subject to intrinsic limitations, with reports of differential interpopulation error rates between geographical locations. This study assessed the accuracy of the S–B method to a contemporary adult population in Queensland, Australia and provides robust age parameters calibrated for our population. Three‐dimensional surface reconstructions were generated from computed tomography scans of the pubic symphysis of male and female Caucasian individuals aged 15–70 years (n = 195) in Amira® and Rapidform®. Error was analyzed on the basis of bias, inaccuracy and percentage correct classification for left and right symphyseal surfaces. Application of transition analysis and Chi‐square statistics demonstrated 63.9 and 69.7% correct age classification associated with the left symphyseal surface of Australian males and females, respectively, using the S–B method. Using Bayesian statistics, probability density distributions for each S–B phase were calculated, providing refined age parameters for our population. Mean inaccuracies of 6.77 (±2.76) and 8.28 (±4.41) years were reported for the left surfaces of males and females, respectively; with positive biases for younger individuals (<55 years) and negative biases in older individuals. Significant sexual dimorphism in the application of the S–B method was observed; and asymmetry in phase classification of the pubic symphysis was a frequent phenomenon. These results recommend that the S–B method should be applied with caution in medico‐legal death investigations of Queensland skeletal remains and warrant further investigation of reliable age estimation techniques. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.     

“Missing perikymata”—fact or fiction? A study on chimpanzee (Pan troglodytes verus) canines

Recently, a lower than expected number of perikymata between repetitive furrow‐type hypoplastic defects has been reported in chimpanzee canines from the Fongoli site, Senegal (Skinner and Pruetz: Am J Phys Anthropol 149 (2012) 468–482). Based on an observation in a localized enamel fracture surface of a canine of a chimpanzee from the Taï Forest (Ivory Coast), these authors inferred that a nonemergence of striae of Retzius could be the cause for the “missing perikymata” phenomenon in the Fongoli chimpanzees. To check this inference, we analyzed the structure of outer enamel in three chimpanzee canines. The teeth were studied using light‐microscopic and scanning‐electron microscopic techniques. Our analysis of the specimen upon which Skinner and Pruetz (Am J Phys Anthropol 149 (2012) 468–482) had made their original observation does not support their hypothesis. We demonstrate that the enamel morphology described by them is not caused by a nonemergence of striae of Retzius but can be attributed to structural variations in outer enamel that result in a differential fracture behavior. Although rejecting the presumed existence of nonemergent striae of Retzius, our study provided evidence that, in furrow‐type hypoplastic defects, a pronounced tapering of Retzius increments can occur, with the striae of Retzius forming acute angles with the outer enamel surface. We suggest that in such cases the outcrop of some striae of Retzius is essentially unobservable at the enamel surface, causing too low perikymata counts. The pronounced tapering of Retzius increments in outer enamel presumably reflects a mild to moderate disturbance of the function of late secretory ameloblasts. Am J Phys Anthropol 157:276–283, 2015. © 2015 Wiley Periodicals, Inc.     

In vivo bone strain and bone functional adaptation

Mechanistic interpretations of bone cross-sectional shapes are based on the paradigm of shape optimization such that bone offers maximum mechanical resistance with a minimum of material. Recent in vivo strain studies (Demes et al., Am J Phys Anthropol 106 (1998) 87-100, Am J Phys Anthropol 116 (2001) 257-265; Lieberman et al., Am J Phys Anthropol 123 (2004) 156-171) have questioned these interpretations by demonstrating that long bones diaphyses are not necessarily bent in planes in which they offer maximum resistance to bending. Potential limitations of these in vivo studies have been pointed out by Ruff et al. (Am J Phys Anthropol 129 (2006) 484-498). It is demonstrated here that two loading scenarios, asymmetric bending and buckling, would indeed not lead to correct predictions of loads from strain. It is also shown that buckling is of limited relevance for many primate long bones. This challenges a widely held view that circular bone cross sections make loading directions unpredictable for bones which is based on a buckling load model. Asymmetric bending is a potentially confounding factor for bones with directional differences in principal area moments (I(max) > I(min)). Mathematical corrections are available and should be applied to determine the bending axis in such cases. It is concluded that loads can be reliably extrapolated from strains. More strain studies are needed to improve our understanding of the relationships between activities, bone loading regimes associated with them, and the cross-sectional geometry of bones.     

Test of revised method of age estimation from the auricular surface of the ilium

The objective of this paper is to test a revised method of age estimation based on the morphology of the auricular surface recently proposed by Buckberry and Chamberlain ([2002] Am. J. Phys. Anthropol. 119:231-239). The study sample consists of 309 individuals of known sex, age, and race from the Terry and Huntington Collections. Auricular surfaces were scored using the revised technique to determine whether it is equally applicable to both sexes as well as blacks and whites. The auricular surfaces of the same individuals were also scored using the original method of auricular surface scoring developed by Lovejoy et al. ([1985] Am. J. Phys. Anthropol. 68:15-28) to determine whether the revised technique is comparable to the original method in terms of accuracy. Results show that the revised method is equally applicable to males and females as well as blacks and whites. The revised method is less accurate than the original method for individuals between 20-49 years of age, but more accurate for individuals between 50-69 years of age.