Biocultural evidence of precise manual activities in an Early Holocene individual of the high-altitude Peruvian Andes.

OBJECTIVES: Cuncaicha, a rockshelter site in the southern Peruvian Andes, has yielded archaeological evidence for human occupation at high elevation (4,480 masl) during the Terminal Pleistocene (12,500-11,200 cal BP), Early Holocene (9,500-9,000 cal BP), and later periods. One of the excavated human burials (Feature 15-06), corresponding to a middle-aged female dated to ~8,500 cal BP, exhibits skeletal osteoarthritic lesions previously proposed to reflect habitual loading and specialized crafting labor. Three small tools found in association with this burial are hypothesized to be associated with precise manual dexterity. MATERIALS AND METHODS: Here, we tested this functional hypothesis through the application of a novel multivariate methodology for the three-dimensional analysis of muscle attachment surfaces (entheses). This original approach has been recently validated on both lifelong-documented anthropological samples as well as experimental studies in nonhuman laboratory samples. Additionally, we analyzed the three-dimensional entheseal shape and resulting moment arms for muscle opponens pollicis. RESULTS: Results show that Cuncaicha individual 15-06 shows a distinctive entheseal pattern associated with habitual precision grasping via thumb-index finger coordination, which is shared exclusively with documented long-term precision workers from recent historical collections. The separate geometric morphometric analysis revealed that the individual's opponens pollicis enthesis presents a highly projecting morphology, which was found to strongly correlate with long joint moment arms (a fundamental component of force-producing capacity), closely resembling the form of Paleolithic hunter-gatherers from diverse geo-chronological contexts of Eurasia and North Africa. DISCUSSION: Overall, our findings provide the first biocultural evidence to confirm that the lifestyle of some of the earliest Andean inhabitants relied on habitual and forceful precision grasping tasks.

Statistical shape analysis of hand and wrist in paediatric population on radiographs

Background/aim: The goal of this study was to compare differences in hand and wrist shapes and to evaluate these according to growth and allometry in children on radiographs related to bone age. Materials and methods: The study included 263 males and 189 females. A total of 452 left hand and wrist radiographs were retrospectively collected. Standard anatomical landmarks marked on radiographs. Results: There were seen to be significant differences in comparisons of hand and wrist shapes according to sex (P = 0.009). The most suitable model in the growth models was seen as the Gompertz growth model for both females and males (model P < 0.001). For the relationship between shape and size to evaluate allometry, significant models were obtained in females (model P = 0.017, MSE = 0.0002) and in males (model P < 0.001, MSE = 0.0002). In our study, the difference between the sexes was found mostly in the radiocarpal region. It was observed that the deformation of the carpal bones started in the distal row carpal bones. Conclusion: Significant differences were found in hand and wrist shapes according to sex. Models for growth and allometry of hand and wrist shapes were found to be significant in children.

Trabecular bone patterning across the human hand.

Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on establishing phylogenetic relationships and/or inferring behavior from epigenetic variation arising from mechanical loading and adaptive bone modeling. Most research focuses on variation in cortical bone structure, but additional information about hand function may be provided through the analysis of internal trabecular structure. While primate hand bone trabecular structure is known to vary in ways that are consistent with expected joint loading differences during manipulation and locomotion, no study exists that has documented this variation across the numerous bones of the hand. We quantify the trabecular structure in 22 bones of the human hand (early/extant modern Homo sapiens) and compare structural variation between two groups associated with post-agricultural/industrial (post-Neolithic) and foraging/hunter-gatherer (forager) subsistence strategies. We (1) establish trabecular bone volume fraction (BV/TV), modulus (E), degree of anisotropy (DA), mean trabecular thickness (Tb.Th) and spacing (Tb.Sp); (2) visualize the average distribution of site-specific BV/TV for each bone; and (3) examine if the variation in trabecular structure is consistent with expected joint loading differences among the regions of the hand and between the groups. Results indicate similar distributions of trabecular bone in both groups, with those of the forager sample presenting higher BV/TV, E, and lower DA, suggesting greater and more variable loading during manipulation. We find indications of higher loading along the ulnar side of the forager sample hand, with high site-specific BV/TV distributions among the carpals that are suggestive of high loading while the wrist moves through the 'dart-thrower's' motion. These results support the use of trabecular structure to infer behavior and have direct implications for refining our understanding of human hand evolution and fossil hominin hand use.

Morphology, diet, and stable carbon isotopes: On the diet of Theropithecus and some limits of uniformitarianism in paleoecology.

Geladas were long supposed to be the only living primates feeding almost entirely on graminoids and accordingly display dramatic dental and manual adaptive traits. A recent study of Theropithecus gelada, the first in a relatively undisturbed habitat, revealed a more diverse diet, also incorporating large quantities of forbs. The peculiar adaptive traits of T. gelada are also observed in extinct Theropithecus as early as 3.7 Ma. Stable carbon isotopic data of extinct Theropithecus from eastern Africa indicate that specimens older than 3 Ma consumed a significant proportion of C3 plants (on average ca. 40% of total food intake) whereas specimens younger than 2 Ma consumed more C4 plants (on average ca. 80%). Recent paleobotanical evidence suggests that C3 herbaceous plants were still present in non-negligible proportions in Plio-Pleistocene lowland tropical ecosystems. Together, the shared morphological adaptive traits of extant and extinct Theropithecus and the varied diets of extant T. gelada suggest that the paleodiets of Theropithecus may have been dominated by herbaceous plants, comprising both C3 forbs and graminoids and C4 graminoids. The changes in stable carbon isotopes could correspond to a replacement of C3 plants by C4 plants within the herbaceous strata rather than a shift from C3 woody vegetation to C4 graminoids. This synthesis highlights the need for a more exhaustive knowledge of the ecology of extant species to achieve meaningful paleodietary and paleoenvironmental reconstructions. A strong selectivity for food resources that are rare in the landscapes (as in T. gelada) should also be considered when interpreting stable carbon isotopes of extinct African mammals (and notably hominids).

Prevalence and distribution of sesamoid bones in the hand determined using digital tomosynthesis.

The aim of this study was to identify the prevalence and distribution of sesamoid bones in the hand using digital tomosynthesis (DTS) in comparison to previous studies. Using conventional radiography (CR) and DTS, hand images (81 left and 100 right) taken at a tertiary hospital were retrospectively reviewed. The sesamoid bones were identified in the interphalangeal (IP) and metacarpophalangeal (MCP) joints of the thumb (I), and in the distal interphalangeal (DIP) and metacarpophalangeal (MCP) of index (II), middle (III), ring (IV), and little (V) fingers. Differences in number of sesamoid bones detected on CR and DTS were analyzed. Sesamoid bones were observed in MCP I (100%), MCP II (46%), MCP III (2%), MCP IV (2%), MCP V (53%), and IP I (53%) on CR. Using DTS, sesamoid bones were found more often in MCP I (100%), MCP II (54%), MCP III (2%), MCP IV (1%), MCP V (59%), and IP I (75%). Differences in the mean number of sesamoid bones detected on CR and DTS were statistically significant. Sesamoid bones in DIP joints were frequently observed on DTS, but rarely found on CR. Most sesamoid bones in the hand were detected in MCP I, II, V, and IP I joints, and were more often detected on DTS than CR. DTS is a reliable tool to evaluate bony structures in the hand. Clin. Anat. 30:608-613, 2017. © 2017 Wiley Periodicals, Inc.

Morphometric patterns among the 3D surface areas of human hand entheses.

OBJECTIVES: This study aimed to put forth a new and precise methodology for calculating the 3D areas of hand entheses. Furthermore, it investigated some of the factors affecting hand entheses development through an assessment of their correlations and morphometric patterns. MATERIALS AND METHODS: Fifty individuals from late-medieval San Pablo were studied. The sample consisted of high-definition 3D models of 17 entheses from the first, second, and fifth hand rays. A new methodology was introduced for quantifying their areas. Precision was verified using intraobserved and interobserver tests. Both raw and relative entheseal size (ratio of entheseal size to total bone surface size) were calculated. Bivariate analyses assessed the effect of age-group on entheses as well as the correlations across entheses of muscles that act synergistically, bone length, and articular surface size. The morphometric patterns among hand entheses were explored using a multivariate analysis. RESULTS: The methodology presented no significant error. Age-group variation does not seem to affect hand entheses. In relative size, only particular pairs presented significant association and the entheses involved were not correlated with bone length or articular surface size. The multivariate analysis demonstrated high sexual dimorphism in overall entheseal size as well as two morphometric trends among hand entheses. DISCUSSION: The proposed methodology can set the basis for further morphological 3D analysis of entheses. If biomechanical stress affects hand entheses, its impact would possibly be greater on their relative size. The morphometric patterns among entheses seem to reflect the performance of prehensile grips. Am J Phys Anthropol 160:694-707, 2016. © 2016 Wiley Periodicals, Inc.

Accuracy of MRI skeletal age estimation for subjects 12-19. Potential use for subjects of unknown age.

INTRODUCTION: In forensic practice, there is a growing need for accurate methods of age estimation, especially in the cases of young individuals of unknown age. Age can be estimated through somatic features that are universally considered associated with chronological age. Unfortunately, these features do not always coincide with the real chronological age: for these reasons that age determination is often very difficult. Our aim is to evaluate accuracy of skeletal age estimation using Tomei's MRI method in subjects between 12 and 19 years old for forensic purposes. MATERIAL AND METHODS: Two investigators analyzed MRI images of the left hand and wrist of 77 male and 74 female caucasian subjects, without chronic diseases or developmental disorders, whose age ranged from 12 to 19 years. Skeletal maturation was determined by two operators, who analyzed all MRI images separately, in blinded fashion to the chronological age. Inter-rater agreement was measured with Pearson (R (2)) coefficient. One of the examiners repeated the evaluation after 6 months, and intraobserver variation was analyzed. Bland-Altman plots were used to determine mean differences between skeletal and chronological age. RESULTS: Inter-rater agreement Pearson coefficient showed a good linear correlation, respectively, 0.98 and 0.97 in males and females. Bland-Altman analysis demonstrated that the differences between chronological and skeletal age are not significant. Spearman's correlation coefficient showed good correlation between skeletal and chronological age both in females (R (2) = 0.96) and in males (R (2) = 0.94). CONCLUSIONS: Our results show that MRI skeletal age is a reproducible method and has good correlation with chronological age.

Value of MRI of the hand and the wrist in evaluation of bone age: preliminary results.

PURPOSE: To evaluate bone age determination using MRI of the hand and wrist. MATERIALS AND METHODS: A total of 179 (78 female and 101 males, 11 to 16 years old) subjects of 252 normal volunteers met entrance criteria. A low field open magnet (0.2 Tesla) was used for this study; coronal T1-weighted images with a slice thickness of 1.3mm were acquired. Two blinded radiologists evaluated the studies and the following elements were considered: the appearance of cartilage, vacuolization of cartilage, provisional calcification, progression of ossification, and complete ossification. Correlation between chronologic age and MR bone age was determined by means of simple linear regression analysis. RESULTS: Strong correlation between MR skeletal age and chronological age was observed for both investigators, Pearson correlation R2 = 0.9 for each. CONCLUSION: Determination of bone age with MRI is feasible and shows good interobserver reproducibility. Data from this study may be useful to develop an atlas of skeletal development and bone age.

Development of a simplified new method of bone age estimation using three bones of the hand and wrist.

Though the Greulich and Pyle (GP) method is easy, inter-observer variability, differential maturation of hand bones influences ratings. The Tanner-Whitehouse (TW) method is more accurate, but cumbersome. A simpler method combining the above, such that it utilizes fewer bones without affecting accuracy, would be widely used and more applicable in clinical practice. OBJECTIVES: 1. Devising a simplified method utilizing three bones of the hand and wrist for bone age (BA) assessment. 2. Testing whether the 3 bone method gives comparable results to standard methods (GP,TW2,TW3) in Indian children. METHODS: Developmental stages and corresponding BA for radius, hamate, terminal phalanx (left middle finger) epiphyses combining stages from GP,TW3 atlases were described; BA were rated by two blinded observers. 3 bone method ratings were compared with the same dataset analyzed earlier using GP,TW2,TW3 (4 raters). RESULTS: Radiographs analysed:493 (Girls=226). Mean chronological age:9.4 ± 4.6 yrs, mean BA 3 bone:9.8 ± 4.8 yrs, GP:9.6 ± 4.8 yrs, TW3:9.3 ± 4.5 yrs, TW2:9.9 ± 5.0 yrs. The 3 bone method demonstrated no significant inter-observer variability (p = 0.3, mean difference = 0.02 ± 0.6 yrs); a strong positive correlation (p < 0.0001) with GP (r = 0.985), TW3 (r = 0.983) and TW2 (r = 0.982) was noted. Bland-Altman plots demonstrated good agreement; the root mean square errors between 3 bone and GP,TW3,TW2 ratings were 0.6,0.7,0.6 years; mean differences were 0.19,0.49,-0.14 years respectively. Greatest proportion of outliers (beyond ±1.96 SD of mean difference) was between 6 and 8 years age for difference in 3 bone and GP, and between 4-6 years for difference in 3 bone and TW3,TW2. CONCLUSION: The 3 bone method has multiple advantages; it is easier, tackles differential maturation of wrist and hand bones, has good reproducibility, without compromising on accuracy rendering it suitable for office practice.

Skeletal age assessment in children using an open compact MRI system.

MRI may be a noninvasive and alternative tool for skeletal age assessment in children, although few studies have reported on this topic. In this article, skeletal age was assessed over a wide range of ages using an open, compact MRI optimized for the imaging of a child's hand and wrist, and its validity was evaluated. MR images and their three-dimensional segmentation visualized detailed skeletal features of each bone in the hand and wrist. Skeletal age was then independently scored from the MR images by two raters, according to the Tanner-Whitehouse Japan system. The skeletal age assessed by MR rating demonstrated a strong positive correlation with chronological age. The intrarater and inter-rater reproducibilities were significantly high. These results demonstrate the validity and reliability of skeletal age assessment using MRI.

Fundamental ratios and logarithmic periodicity in human limb bones.

Fundamental mathematical relationships are widespread in biology yet there is little information on this topic with regard to human limb bone lengths and none related to human limb bone volumes. Forty-six sets of ipsilateral upper and lower limb long bones and third digit short bones were imaged by computed tomography. Maximum bone lengths were measured manually and individual bone volumes calculated from computed tomography images using a stereologic method. Length ratios of femur : tibia and humerus : ulna were remarkably similar (1.21 and 1.22, respectively) and varied little (<7%) between individuals. The volume ratio of femur : tibia was approximately half that of humerus : ulna (1.58 and 3.28, respectively; P < 0.0001). Lower limb bone volume ratios varied much more than upper limb ratios. The relationship between bone length and volume was found to be well described by power laws, with R(2) values ranging from 0.983 to 0.995. The most striking finding was a logarithmic periodicity in bone length moving from distal to proximal up the limb (upper limb λ = 0.72, lower limb λ = 0.93). These novel data suggest that human limb bone lengths and volumes follow fundamental and highly conserved mathematical relationships, which may contribute to our understanding of normal and disordered growth, stature estimation, and biomechanics.

Reassessing manual proportions in Australopithecus afarensis.

Previous analyses of hand morphology in Australopithecus afarensis have concluded that this taxon had modern human-like manual proportions, with relatively long thumbs and short fingers. These conclusions are based on the A.L.333 composite fossil assemblage from Hadar, Ethiopia, and are premised on the ability to assign phalanges to a single individual, and to the correct side and digit. Neither assignment is secure, however, given the taphonomy and sample composition at A.L.333. We use a resampling approach that includes the entire assemblage of complete hand elements at Hadar, and takes into account uncertainties in identifying phalanges by individual, side and digit number. This approach provides the most conservative estimates of manual proportions in Au. afarensis. We resampled hand long bone lengths in Au. afarensis and extant hominoids, and obtained confidence limits for distributions of manual proportions in the latter. Results confirm that intrinsic manual proportions in Au. afarensis are dissimilar to Pan and Pongo. However, manual proportions in Au. afarensis often fall at the upper end of the distribution in Gorilla, and very lower end in Homo, corresponding to disproportionately short thumbs and long medial digits in Homo. This suggests that manual proportions in Au. afarensis, particularly metacarpal proportions, were not as derived towards Homo as previously described, but rather are intermediate between gorillas and humans. Functionally, these results suggest Au. afarensis could not produce precision grips with the same efficiency as modern humans, which may in part account for the absence of lithic technology in this fossil taxon.

Neanderthal hand and foot remains from Moula-Guercy, Ardèche, France.

The hand and foot remains from Moula-Guercy cave (Ardèche, France) comprise 24 specimens of Eemian age (ca. 120 ka). The specimens include primarily complete elements, which are rare among the Moula-Guercy postcrania. The hand remains have several characteristic Neanderthal traits including a laterally facing (parasagittally oriented) second metacarpal-capitate articulation, a short styloid process, a wide proximal articular surface on the third metacarpal, and absolutely expanded apical tuberosities on the distal hand phalanges relative to modern humans. The foot remains include several incomplete elements along with an antimeric pair of naviculars, a medial cuneiform and cuboid, and a single complete element from each of the distal segments (one each: metatarsal, proximal foot phalanx, intermediate foot phalanx, distal foot phalanx). Consistent among the specimens are relatively wide diaphyses for length in the metatarsals and phalanges and large and prominent muscle attachments, both consistent with previously published Neanderthal morphology. The hand and foot collection from Moula-Guercy is an important dataset for future studies of Neanderthal functional morphology, dexterity, and behavior as it represents a previously undersampled time period for European Neanderthals.

Hands of early primates.

Questions surrounding the origin and early evolution of primates continue to be the subject of debate. Though anatomy of the skull and inferred dietary shifts are often the focus, detailed studies of postcrania and inferred locomotor capabilities can also provide crucial data that advance understanding of transitions in early primate evolution. In particular, the hand skeleton includes characteristics thought to reflect foraging, locomotion, and posture. Here we review what is known about the early evolution of primate hands from a comparative perspective that incorporates data from the fossil record. Additionally, we provide new comparative data and documentation of skeletal morphology for Paleogene plesiadapiforms, notharctines, cercamoniines, adapines, and omomyiforms. Finally, we discuss implications of these data for understanding locomotor transitions during the origin and early evolutionary history of primates. Known plesiadapiform species cannot be differentiated from extant primates based on either intrinsic hand proportions or hand-to-body size proportions. Nonetheless, the presence of claws and a different metacarpophalangeal [corrected] joint form in plesiadapiforms indicate different grasping mechanics. Notharctines and cercamoniines have intrinsic hand proportions with extremely elongated proximal phalanges and digit rays relative to metacarpals, resembling tarsiers and galagos. But their hand-to-body size proportions are typical of many extant primates (unlike those of tarsiers, and possibly Teilhardina, which have extremely large hands). Non-adapine adapiforms and omomyids exhibit additional carpal features suggesting more limited dorsiflexion, greater ulnar deviation, and a more habitually divergent pollex than observed plesiadapiforms. Together, features differentiating adapiforms and omomyiforms from plesiadapiforms indicate increased reliance on vertical prehensile-clinging and grasp-leaping, possibly in combination with predatory behaviors in ancestral euprimates.

Physiological bone responses in the fingers after more than 10 years of high-level sport climbing: analysis of cortical parameters.

OBJECTIVE: Sports activity can induce bone modeling processes with apposition of new bone and changes in bone morphology. Sport climbing places extreme forces and stress on the hands, especially on the bones of the fingers. This study examines sports-induced physiological adaptations of the finger bones of climbers. METHODS: In this cohort study, the radiographs of 31 high-level (Union Internationale des Associations d'Alpinisme [UIAA] metric scale range 8.33 to 11.33), experienced (median 20 years climbing time) adult climbers were compared with those of a control group of 67 patients. Cortical dimensions and variables were measured and analyzed in a total of 330 fingers. An association analysis of climbing-related variables was also performed. RESULTS: The climber's bones showed a 25% higher cortical proportion than those of the control group. On average, the outer cortical width of the climbers' bones was 6% larger and the medullary canal was 20% narrower than in the control group (P < .05). The differences between groups were more pronounced in the sagittal plane and more pronounced distally in the fingers. No associations were found between age, climbing experience, climbing level, and the cortical hypertrophy. CONCLUSIONS: Differences in bone morphology can be observed in the finger bones of adult climbers when compared with controls. Because the differences are more pronounced at the palmar and dorsal cortices, the analysis of the sagittal plane should always be included in future investigations. To evaluate climbing-related factors influencing these adaptive morphologic differences, further studies with larger, more specific study cohorts are needed.

Registration-based segmentation with articulated model from multipostural magnetic resonance images for hand bone motion animation.

PURPOSE: The quantitative measurements of hand bones, including volume, surface, orientation, and position are essential in investigating hand kinematics. Moreover, within the measurement stage, bone segmentation is the most important step due to its certain influences on measuring accuracy. Since hand bones are small and tubular in shape, magnetic resonance (MR) imaging is prone to artifacts such as nonuniform intensity and fuzzy boundaries. Thus, greater detail is required for improving segmentation accuracy. The authors then propose using a novel registration-based method on an articulated hand model to segment hand bones from multipostural MR images. METHODS: The proposed method consists of the model construction and registration-based segmentation stages. Given a reference postural image, the first stage requires construction of a drivable reference model characterized by hand bone shapes, intensity patterns, and articulated joint mechanism. By applying the reference model to the second stage, the authors initially design a model-based registration pursuant to intensity distribution similarity, MR bone intensity properties, and constraints of model geometry to align the reference model to target bone regions of the given postural image. The authors then refine the resulting surface to improve the superimposition between the registered reference model and target bone boundaries. RESULTS: For each subject, given a reference postural image, the proposed method can automatically segment all hand bones from all other postural images. Compared to the ground truth from two experts, the resulting surface image had an average margin of error within 1 mm (mm) only. In addition, the proposed method showed good agreement on the overlap of bone segmentations by dice similarity coefficient and also demonstrated better segmentation results than conventional methods. CONCLUSIONS: The proposed registration-based segmentation method can successfully overcome drawbacks caused by inherent artifacts in MR images and obtain more accurate segmentation results automatically. Moreover, realistic hand motion animations can be generated based on the bone segmentation results. The proposed method is found helpful for understanding hand bone geometries in dynamic postures that can be used in simulating 3D hand motion through multipostural MR images.

The cannabinoid receptor type 2 (CNR2) gene is associated with hand bone strength phenotypes in an ethnically homogeneous family sample.

Genetic variants within the CNR2 gene encoding the cannabinoid receptor CB2 have been shown to be associated with osteoporosis and low bone mineral density (BMD) in case-control studies. We now examined the association of polymorphisms in CNR2 with hand bone strength in an ethnically homogeneous healthy family sample of European origin (Chuvashians) living in Russia. We show that non-synonymous CNR2 SNPs are significantly associated with radiographic hand BMD and breaking bending resistance index (BBRI) by two different transmission disequilibrium tests. For both tests highly significant p values (ranging from 0.007 to 0.008 for hand BMD, and from 0.001 to 0.003 for BBRI) were also obtained with additional SNPs at the CNR2 locus. The associations remained significant after correction for multiple testing. In conclusion, in addition to the association of CNR2 polymorphisms with low BMD at selected clinically relevant skeletal sites, we now report their significant association with hand bone strength phenotypes using a family-based study design implying an even broader impact of genetic variation at the CNR2 locus on bone structure and function.

The digital atlas of skeletal maturity by Gilsanz and Ratib: a suitable alternative for age estimation of living individuals in criminal proceedings?

As a collection of radiographic standards of the normal hand development with a homogenous degree of maturity of all skeletal elements, the digital atlas of skeletal maturity by Gilsanz and Ratib combines the possibilities of digital imaging with the principle of a conventional atlas method. The present paper analyses the forensic applicability of skeletal age assessment according to Gilsanz and Ratib to age estimation in criminal proceedings. For this, the hand X-rays of 180 children and adolescents aged 10-18 years old were examined retrospectively. For the entire age range, the minima and maxima, the mean values and standard deviations as well as the medians with upper and lower quartiles are specified by sex. For the legally relevant age groups from 14 to 18 years, there is a risk of overestimation of the chronological age of up to 7.2 months in females. The method of Gilsanz and Ratib is therefore only suitable to forensic age estimation in criminal proceedings to a limited extent.