Osteonal Damage Patterns from Ballistic and Blunt Force Trauma in Human Long Bones.

Forensic anthropologists play a key role in skeletal trauma analysis and commonly use macroscopic features to distinguish between trauma types. However, this approach can be challenging, particularly in cases of highly comminuted or incompletely recovered fractures. Histological analysis of microscopic fracture characteristics in fractured bones may thus help provide additional information on trauma type and bone fracture biomechanics in general. This study analysed the extent of microcrack damage to osteons in long bones with blunt force trauma (BFT) and gunshot trauma (GST), from both traumatic death cases and post-mortem experimental fractures. We identified four types of osteonal damage (OD). In traumatic death cases, OD affecting the inside of the osteon and compromising the Haversian canal (type 1) was found to be indicative of BFT. Moreover, OD affecting the cement line (type 3) and interstitial lamellae (type 4) was more common in the GST samples. OD affecting the inside of the osteon without compromising the Haversian canal (type 2) was not found to be indicative of either trauma type. In cases of experimental fractures, our study revealed that post-mortem fractures in dry bone samples featured the highest amount of OD, particularly of type 4. This study also found that the experimentally produced GST featured similar OD patterns to GST death cases. These findings support our hypothesis that there are distinct osteonal damage patterns in human long bones with BFT and GST, which are of relevant value for trauma analysis in forensic anthropology.

Ballistic long bone fracture pattern: an experimental study.

When dealing with badly preserved cadavers or skeletal human remains, the assessment of death circumstances remains challenging. When forensic evidence cannot be taken from the skin and soft tissue, the information may only be deduced from more resistant elements such as bone. Compared to cranial gunshot injuries, reliable data on ballistic long bone trauma remains scarce. This study aims to define ballistic fracture characteristics in human long bones. The shaft of 16 femurs and 13 humeri from body donors was perpendicularly shot with a 9-mm Luger full metal jacket bullet at an impact velocity of 360 m/s from a distance of 2 m. Some bones were embedded in Clear Ballistics Gel®, and some were shot without soft tissue simulant in order to better visualise the fracture propagation on the high-speed camera. The fractures were examined macroscopically and compared between the sample groups. We consistently found comminuted fractures with a stellate pattern. Fracture details were classified into entrance, exit and general characteristics. For some traits, we detected different occurrence values in the group comparison. The results indicate that some of the traits depend on bone properties such as shaft diameter, bone length and cortical thickness. The presence of ballistic gel also influenced some fracture traits, emphasising the relevance of soft tissue simulant in osseous gunshot experiments. This study revealed new insights in the detailed fracture pattern of human long bones. These may serve as guidelines for the identification and reconstruction of gunshot trauma in human long bones.

Using an embryo specific promoter to modify iron distribution pattern in Arabidopsis.

Iron is an essential micronutrient for life. During the development of the seed, iron accumulates during embryo maturation. In Arabidopsis thaliana, iron mainly accumulates in the vacuoles of only one cell type, the cell layer that surrounds provasculature in hypocotyl and cotyledons. Iron accumulation pattern in Arabidopsis is an exception in plant phylogeny, most part of the dicot embryos accumulate iron in several cell layers including cortex and, in some cases, even in protodermis. It remains unknown how does iron reach the internal cell layers of the embryo, and in particular, the molecular mechanisms responsible of this process. Here, we use transgenic approaches to modify the iron accumulation pattern in an Arabidopsis model. Using the SDH2-3 embryo-specific promoter, we were able to express VIT1 ectopically in both a wild type background and a mutant vit1 background lacking expression of this vacuolar iron transporter. These manipulations modify the iron distribution pattern in Arabidopsis from one cell layer to several cell layers, including protodermis, cortex cells, and the endodermis. Interestingly, total seed iron content was not modified compared with the wild type, suggesting that iron distribution in embryos is not involved in the control of the total iron amount accumulated in seeds. This experimental model can be used to study the processes involved in iron distribution patterning during embryo maturation and its evolution in dicot plants.

Growth Developmental Defects of Mitochondrial Iron Transporter 1 and 2 Mutants in Arabidopsis in Iron Sufficient Conditions.

Iron is the most abundant micronutrient in plant mitochondria, and it has a crucial role in biochemical reactions involving electron transfer. It has been described in Oryza sativa that Mitochondrial Iron Transporter (MIT) is an essential gene and that knockdown mutant rice plants have a decreased amount of iron in their mitochondria, strongly suggesting that OsMIT is involved in mitochondrial iron uptake. In Arabidopsis thaliana, two genes encode MIT homologues. In this study, we analyzed different AtMIT1 and AtMIT2 mutant alleles, and no phenotypic defects were observed in individual mutant plants grown in normal conditions, confirming that neither AtMIT1 nor AtMIT2 are individually essential. When we generated crosses between the Atmit1 and Atmit2 alleles, we were able to isolate homozygous double mutant plants. Interestingly, homozygous double mutant plants were obtained only when mutant alleles of Atmit2 with the T-DNA insertion in the intron region were used for crossings, and in these cases, a correctly spliced AtMIT2 mRNA was generated, although at a low level. Atmit1 Atmit2 double homozygous mutant plants, knockout for AtMIT1 and knockdown for AtMIT2, were grown and characterized in iron-sufficient conditions. Pleiotropic developmental defects were observed, including abnormal seeds, an increased number of cotyledons, a slow growth rate, pinoid stems, defects in flower structures, and reduced seed set. A RNA-Seq study was performed, and we could identify more than 760 genes differentially expressed in Atmit1 Atmit2. Our results show that Atmit1 Atmit2 double homozygous mutant plants misregulate genes involved in iron transport, coumarin metabolism, hormone metabolism, root development, and stress-related response. The phenotypes observed, such as pinoid stems and fused cotyledons, in Atmit1 Atmit2 double homozygous mutant plants may suggest defects in auxin homeostasis. Unexpectedly, we observed a possible phenomenon of T-DNA suppression in the next generation of Atmit1 Atmit2 double homozygous mutant plants, correlating with increased splicing of the AtMIT2 intron containing the T-DNA and the suppression of the phenotypes observed in the first generation of the double mutant plants. In these plants with a suppressed phenotype, no differences were observed in the oxygen consumption rate of isolated mitochondria; however, the molecular analysis of gene expression markers, AOX1a, UPOX, and MSM1, for mitochondrial and oxidative stress showed that these plants express a degree of mitochondrial perturbation. Finally, we could establish by a targeted proteomic analysis that a protein level of 30% of MIT2, in the absence of MIT1, is enough for normal plant growth under iron-sufficient conditions.

Osteonal Microcracking Pattern: A Potential Vitality Marker in Human Bone Trauma.

In forensic anthropology, the differential diagnosis between peri- and postmortem bone fractures is mainly based on macroscopic criteria. In contrast, studies focusing on bone histology are very scarce. In a recent publication, we showed that (perimortem) fractures in fresh human bones exhibit a different osteonal microcracking pattern than (postmortem) damage in dry bones. In the current work, we explored whether this osteonal microcracking pattern is distinctive of the vitality of (perimortem) fresh bone fractures. To this end, we compared the number, length and structural distribution of microcracks in vital humeral fractures from forensic autopsy cases with experimentally reproduced, three point-bending fractures in fresh and dry human humeri. Half of the fresh experimental bones were fractured whilst applying axial compression, i.e., attempting to simulate intra vitam conditions more accurately. The results showed a similar osteonal microcracking pattern between vital fractures and experimental fractures of fresh humeri subjected to axial compression. Interestingly, this pattern was significantly different from the one observed in the experimental fractures of fresh humeri without axial compression and dry humeri. This supports our hypothesis that the osteonal microcracking pattern can potentially be used as a marker for vital perimortem trauma, providing a histomorphometric tool for fracture timing.

Microcracking pattern in fractured bones: new approach for distinguishing between peri- and postmortem fractures.

Timing bone fractures is one of the main tasks of a forensic anthropologist, but still an uncertain diagnostic. In the literature, there are many macroscopic methods to distinguish perimortem from postmortem fractures, based on the distinct structural and mechanical properties of fresh and dry bones. However, this differentiation is still challenging, in particular when the bones are fragmented or still exhibit fresh properties. Although histologic analysis is often used as a complementary diagnostic tool in forensic pathology, its application in the evaluation of bone fractures is uncommon. The aim of this study was to investigate whether fractures of fresh bones reveal a distinct microcracking pattern compared to fractures of dry bones, in order to optimise the fracture timing. To this purpose, we histologically analysed perimortem and postmortem fractures in human humeri. The fresh bones were retrieved from traumatic autopsy cases, and the dry bones from donors which were experimentally fractured. Our results showed that the highest density and length of microcracks (MCKs) were found in the interstitial area of dry fractured bones, which may be considered a marker of postmortem damage. In fresh fractured bones, we generally observed a lower density of MCKs, but a higher proportion of osteonal MCKs, which may be considered a marker of perimortem trauma. In summary, the results of our exploratory study suggest that changes in intrinsic bone factors (mineral/organic components) result in a different microcracking pattern that can be used in fracture timing.

Taphonomic model of decomposition.

After death human body is subject to the processes of autolysis and putrefaction. Notably, the changes in cadaver during decomposition complicate its forensic analysis and particularly the estimation of the post-mortem interval (PMI). The process and rate of decomposition is impacted by various intrinsic and extrinsic factors that vary across countries and regions. Studying the decomposition pattern in different regions in the world helps us to understand the process and improve the precision of the PMI estimation of decomposed bodies. With the aim to develop a taphonomic model of decomposition in the province of Barcelona (Catalonia, Spain), this study analyses the influence of several intrinsic and extrinsic factors in the pattern and rate of decomposition in this geographical area. Our statistical model concluded that the most significant factors affecting the decomposition pattern and rate are temperature and PMI. Nevertheless, there are other intrinsic factors such as cause, manner of death and underlying pathological conditions which also have an important role. Moreover, considering the various variables studied in this research, two predictive machine learning algorithms were developed as a probabilistic approach to estimate the PMI. Reliable classification results are obtained for three interval groups (1-2 days, 3-10 days, and > 10 days) and two interval groups (>1 week, < 1 week). Machine learning algorithm is a promising tool to gain objectivity in forensic PMI assessments. The results of this study could potentially assist further research in forensic taphonomy.

A new methodology to estimate flat foot in skeletal remains - the example of Mediterranean collections.

Flat feet (pes planus) are considered a postural defect caused by the collapse of the longitudinal arch, producing complete or near-complete contact of the sole of the foot with the ground. Pes planus has been well-studied in clinical literature and paleoanthropology but has not been approached extensively in bioarchaeology. The main difficulty is related to the diagnosis of this pathology based exclusively on bone remains. In this work, we propose a metric and morphological method to discriminate flat foot in dry bones. Thus, we studied 390 pairs of adult feet in a fair state of preservation from archaeological contexts from Spain, Italy, and Oman. Morphological variability, angles, and dimensions of both the normal bones and the bones displaying flat foot characteristics were analyzed. We found a correlation between the presence of flat foot and some morphological and metric features, mainly in the subtalar and Chopart joints. These results are expressed through a combination of morphological and metric variables, which are useful to discriminate between these two groups. No markedly significant differences of flat foot frequencies between the Spanish and Italian series were found across centuries. However, we noticed a notable increase of the prevalence of flat foot in the contemporary collection, possibly due to the consequences of a rise in life expectancy and modern styles of footwear.

Technical note: preliminary insight into a new method for age-at-death estimation from the pubic symphysis.

Age-at-death estimation methods are important in forensic anthropology. However, age assessment is problematic due to inter-individual variation. The subjectivity of visual scoring systems can affect the accuracy and reliability of methods as well. One of the most studied skeletal regions for age assessment is the pubic symphysis. Few studies on Spanish pubic symphysis collections have been conducted, making further research necessary as well as the sampling of more forensic skeletal collections. This study is a preliminary development of an age-at-death estimation method from the pubic symphysis based on a new simple scoring system. A documented late twentieth century skeletal collection (N = 29) and a twenty-first century forensic collection (N = 76) are used. Sixteen traits are evaluated, and a new trait (microgrooves) is described and evaluated for the first time in this study. All traits are scored in a binary manner (present or absent), thus reducing ambiguity and subjectivity. Several data sets are constructed based on different age intervals. Machine learning methods are employed to evaluate the scoring system's performance. The results show that microgrooves, macroporosity, beveling, lower extremity, ventral and dorsal margin decomposition, and lipping are the best preforming traits. The new microgroove trait proves to be a good age predictor. Reliable classification results are obtained for three age intervals (≤ 29, 30-69, ≥ 70). Older individuals are reliably classified with two age intervals (< 80, ≥ 80). The combination of binary attributes and machine learning algorithms is a promising tool for gaining objectivity in age-at-death assessment.

Distinction between perimortem and postmortem fractures in human cranial bone.

Timing of cranial trauma is challenging in forensic cases and literature on the subject is scarce. This study analysed the macroscopic fracture patterns of perimortem cranial fractures and compared them to experimentally reproduced cranial fractures on dry human craniums. The results showed nine traits associated with fresh cranial fractures: undulated margin, flake defects, peels with peel defects, fissures, crushed margins, bridge, bone scales and beveling. All the traits appear on the outer table or on the inner table of the cranium. Although not all characteristics must be present at the same time in all cranial fractures, they do define a new perimortem fracture pattern. Statistical analyses showed that six of these traits (undulated margins, flake defects, crushed margins, bone scales, fissures and peels) are distinctly related with perimortem (fresh) bone conditions. Considering the most discriminant perimortem traits, a decision-making algorithm is developed as a probabilistic approach to distinguish peri- from postmortem cranial fractures with an accuracy of 87%. This algorithm allows the forensic practitioner to incorporate more confidence during cranial trauma evaluation.

Morphological and biomechanical implications of cuboid facet of the navicular bone in the gait / Implicaciones morfológicas y biomecánicas de la faceta cuboídea del navicular en la marcha

The cuboid facet of the navicular bone is an irregular flat surface, present in non-human primates and some human ancestors. In modern humans, it is not always present and it is described as an "occasional finding". To date, there is not enough data about its incidence in ancient and contemporary populations, nor a biomechanical explanation about its presence or absence. The aim of the study was to evaluate the presence of the cuboid facet in ancient and recent populations, its relationship with the dimensions of the midtarsal bones and its role in the biomechanics of the gait. 354 pairs of naviculars and other tarsal bones from historical and contemporary populations from Catalonia, Spain, have been studied. We used nine measurements applied to the talus, navicular, and cuboid to check its relationship with facet presence. To analyze biomechanical parameters of the facet, X-ray cinematography was used in living patients. The results showed that about 50 % of individuals developed this surface without differences about sex or series. We also observed larger sagittal lengths of the talar facet (LSAGTAL) in navicular bones with cuboid facet. No significant differences were found in the bones contact during any of the phases of the gait. After revising its presence in hominins and non-human primates, and its implication in the bipedalism and modern gait, we suggest that cuboid facet might be related with the size of talar facet and the position of the talonavicular joint. However, other factors such as geographical conditions, genetics and stressful activities probably affect its presence too.

La faceta cuboídea del hueso navicular es una carilla plana e irregular, presente en primates no humanos y en algunos de nuestros ancestros. En humanos modernos, no siempre está presente y es descrita como "un hallazgo ocasional" por la bibliografía. Hasta la fecha, no hay suficientes datos acerca de su incidencia en poblaciones antiguas y contemporáneas, ni una explicación biomecánica sobre su presencia o ausencia. El objetivo de nuestro estudio fue evaluar la frecuencia de la faceta cuboídea en poblaciones recientes y antiguas, su relación con las dimensiones de los huesos tarsales y su rol en la biomecánica de la marcha. Fueron estudiados 354 pares de naviculares y otros huesos del tarso provenientes de colecciones osteológicas de Cataluña, España. Aplicamos nueve medidas aplicadas al talus, navicular y cuboides para corroborar su relación con la presencia de la faceta. Para analizar sus parámetros biomecánicos, se empleó X-ray cinematography en pacientes hospitalarios. Los resultados mostraron que alrededor de un 50 % de los individuos desarrollaron esta carilla, sin diferencias entre sexos o series. Además, observamos que la longitud sagital de la faceta talar (LSAGTAL) es mayor en aquellas muestras con faceta cuboídea. No hay diferencias significativas en el contacto de los huesos en ninguna de las fases de la marcha. Después de revisar su presencia en primates no humanos, su implicancia en el bipedismo y en la marcha moderna, sugerimos que la faceta cuboídea podría estar relacionada con el tamaño de la faceta talar y la posición de la articulación talo-navicular. Sin embargo, otros factores como las condiciones geográficas, genética y stress ocupacional también podrían afectar su presencia.

Intra vitam trauma pattern: changing the paradigm of forensic anthropology?

This study aims to improve a previous study that reported new traits to characterize a perimortem fracture pattern in human long bones. This second study aims to acquire further knowledge about these perimortem traits, specifically by improving the experimental setting-by using a Blunt Force Trauma Simulator-and increasing the sample size with a total of 43 autopsy specimens and 57 reproduced fractures. Additionally, we investigated whether these traits could be related to muscular contractions by adding axial compression in the experimentally fractured specimens. If intra vitam traits can be found, it would consequentially be more valuable for forensic anthropologists to shorten the perimortem period. We demonstrate that all traits are perimortem traits. Furthermore, based on our results, we see the tendency that the combination of traits-instead of the presence of each trait individually-may make it possible to distinguish intra vitam from perimortem fractures. This study confirms these distinct characteristics that can be valuable to utilize in the distinction between peri- and postmortem fractures.

Perimortem fracture pattern in ribs by blunt force trauma.

Literature on timing of rib trauma is scarce but remains challenging during forensic cases. This study analysed the macroscopic fracture patterns of perimortem rib fractures and compared them to experimentally reproduced rib fractures on fresh and dry ribs. Six distinctive macroscopic traits were found in ribs that might provide information about the timing of trauma, fracture mechanism and/or trauma circumstances. These traits are peels, folds, differential fracture edges, incomplete fractures, plastic deformation and longitudinal lines. Peels, folds and plastic deformation might provide information about trauma timing. Folds and different fracture edges might provide information about the fracture mechanism. Statistical analyses showed that longitudinal lines, folds and incomplete fractures might provide information about the trauma circumstances and that age might have an influence on the occurrence of complete fractures, longitudinal lines and peels (p ≤ 0.05). The new insights presented in this study might be valuable for forensic anthropologists in rib trauma analysis.

The Pentatricopeptide Repeat Protein MEF31 is Required for Editing at Site 581 of the Mitochondrial tatC Transcript and Indirectly Influences Editing at Site 586 of the Same Transcript.

Pentatricopeptide repeat (PPR) proteins constitute the largest family of proteins in angiosperms, and most members are predicted to play roles in the maturation of organellar RNAs. Here we describe the novel mitochondrial editing factor 31 (MEF31), an E-PPR protein involved in editing at two close sites in the same transcript encoding subunit C of the twin-arginine translocation (tat) pathway. MEF31 is essential for editing at site tatC-581 and application of the recently proposed amino acid code for RNA recognition by PPR proteins supports the view that MEF31 directly targets this site by recognizing its cis sequence. In contrast, editing at site tatC-586 five nucleotides downstream is only partially affected in plants lacking MEF31, being restored to wild-type levels in complemented plants. Application of the amino acid code and analysis of individual RNA molecules for editing at sites 581 and 586 suggest that MEF31 does not directly target site tatC-586, and only indirectly influences editing at this site. It is likely that editing at site tatC-581 improves recognition of the site tatC-586 cis sequence by a second unknown PPR protein.

Reconstructing molar growth from enamel histology in extant and extinct Equus.

The way teeth grow is recorded in dental enamel as incremental marks. Detailed analysis of tooth growth is known to provide valuable insights into the growth and the pace of life of vertebrates. Here, we study the growth pattern of the first lower molar in several extant and extinct species of Equus and explore its relationship with life history events. Our histological analysis shows that enamel extends beyond the molar's cervix in these mammals. We identified three different crown developmental stages (CDS) in the first lower molars of equids characterised by different growth rates and likely to be related to structural and ontogenetic modifications of the tooth. Enamel extension rate, which ranges from ≈400 µm/d at the beginning of crown development to rates of ≈30 µm/d near the root, and daily secretion rate (≈17 µm/d) have been shown to be very conservative within the genus. From our results, we also inferred data of molar wear rate for these equids that suggest higher wear rates at early ontogenetic stages (13 mm/y) than commonly assumed. The results obtained here provide a basis for future studies of equid dentition in different scientific areas, involving isotope, demographic and dietary studies.

Forearm pronation efficiency in A.L. 288-1 (Australopithecus afarensis) and MH2 (Australopithecus sediba): Insights into their locomotor and manipulative habits.

OBJECTIVES: The locomotor and manipulative abilities of australopithecines are highly debated in the paleoanthropological context. Australopithecus afarensis and Australopithecus sediba likely engaged in arboreal locomotion and, especially the latter, in certain activities implying manipulation. Nevertheless, their degree of arboreality and the relevance of their manipulative skills remain unclear. Here we calculate the pronation efficiency of the forearm (Erot ) in these taxa to explore their arboreal and manipulative capabilities using a biomechanical approach. MATERIALS AND METHODS: Three-dimensional humeral images and upper limb measurements of A.L. 288-1 (Au. afarensis) and MH2 (Au. sediba) were used to calculate Erot using a previously described biomechanical model. RESULTS: Maximal Erot in elbow flexion occurs in a rather supinated position of the forearm in Au. afarensis, similarly to Pan troglodytes. In elbow extension, maximal Erot in this fossil taxon occurs in the same forearm position as in Pongo spp. In Au. sediba the forearm positions where Erot is maximal are largely coincident with those for Hylobatidae. CONCLUSIONS: The pattern in Au. afarensis suggests relevant arboreal capabilities, which would include vertical climbing, although it is suggestive of poorer manipulative skills than in modern humans. The similarity between Au. sediba and Hylobatidae is difficult to interpret, but the differences between Au. sediba and Au. afarensis suggest that the capacity to rotate the forearm followed different evolutionary processes in these australopithecine species. Although functional inferences from the upper limb are complex, the observed differences between both taxa point to the existence of two distinct anatomical models.

An active Mitochondrial Complex II Present in Mature Seeds Contains an Embryo-Specific Iron-Sulfur Subunit Regulated by ABA and bZIP53 and Is Involved in Germination and Seedling Establishment.

Complex II (succinate dehydrogenase) is an essential mitochondrial enzyme involved in both the tricarboxylic acid cycle and the respiratory chain. In Arabidopsis thaliana, its iron-sulfur subunit (SDH2) is encoded by three genes, one of them (SDH2.3) being specifically expressed during seed maturation in the embryo. Here we show that seed SDH2.3 expression is regulated by abscisic acid (ABA) and we define the promoter region (-114 to +49) possessing all the cis-elements necessary and sufficient for high expression in seeds. This region includes between -114 and -32 three ABRE (ABA-responsive) elements and one RY-enhancer like element, and we demonstrate that these elements, although necessary, are not sufficient for seed expression, our results supporting a role for the region encoding the 5' untranslated region (+1 to +49). The SDH2.3 promoter is activated in leaf protoplasts by heterodimers between the basic leucine zipper transcription factors bZIP53 (group S1) and bZIP10 (group C) acting through the ABRE elements, and by the B3 domain transcription factor ABA insensitive 3 (ABI3). The in vivo role of bZIP53 is further supported by decreased SDH2.3 expression in a knockdown bzip53 mutant. By using the protein synthesis inhibitor cycloheximide and sdh2 mutants we have been able to conclusively show that complex II is already present in mature embryos before imbibition, and contains mainly SDH2.3 as iron-sulfur subunit. This complex plays a role during seed germination sensu-stricto since we have previously shown that seeds lacking SDH2.3 show retarded germination and now we demonstrate that low concentrations of thenoyltrifluoroacetone, a complex II inhibitor, also delay germination. Furthermore, complex II inhibitors completely block hypocotyl elongation in the dark and seedling establishment in the light, highlighting an essential role of complex II in the acquisition of photosynthetic competence and the transition from heterotrophy to autotrophy.

Histological variability in the limb bones of the Asiatic wild ass and its significance for life history inferences.

The study of bone growth marks (BGMs) and other histological traits of bone tissue provides insights into the life history of present and past organisms. Important life history traits like longevity or age at maturity, which could be inferred from the analysis of these features, form the basis for estimations of demographic parameters that are essential in ecological and evolutionary studies of vertebrates. Here, we study the intraskeletal histological variability in an ontogenetic series of Asiatic wild ass (Equus hemionus) in order to assess the suitability of several skeletal elements to reconstruct the life history strategy of the species. Bone tissue types, vascular canal orientation and BGMs have been analyzed in 35 cross-sections of femur, tibia and metapodial bones of 9 individuals of different sexes, ages and habitats. Our results show that the number of BGMs recorded by the different limb bones varies within the same specimen. Our study supports that the femur is the most reliable bone for skeletochronology, as already suggested. Our findings also challenge traditional beliefs with regard to the meaning of deposition of the external fundamental system (EFS). In the Asiatic wild ass, this bone tissue is deposited some time after skeletal maturity and, in the case of the femora, coinciding with the reproductive maturity of the species. The results obtained from this research are not only relevant for future studies in fossil Equus, but could also contribute to improve the conservation strategies of threatened equid species.

Sex estimation from the navicular bone in Spanish contemporary skeletal collections.

Sexual estimation is fundamental to reconstruct the biological profile of individuals, but postdepositional factors can alter the resistance of the bones, thereby preventing accurate diagnosis especially when the skull and the pelvis are absent. Navicular bones are usually well preserved in archeological and forensic contexts and can a good alternative to discriminate sex. On the basis of these aspects, the present investigation analyzed the sexual dimorphism in 231 pairs of navicular bones from documented contemporary collections from Spain. Receiver operating characteristic (ROC) curve analysis and binary logistic regressions were carried out in eight replicable linear measurements of the navicular bone. Each of the eight variables showed a significant sexual dimorphism in our sample. The ROC curve results indicate that at least five out of the eight variables used have high ability for sex diagnosis, among which the maximum length of the cuneiform surface (LMAXCUN) showed a better performance (area under the curve value=0.86). Moreover, we introduced regression equations with combination of measurements that correctly allocated the skeletons with 80% or greater accuracy. The equation with high allocation accuracy rate (83.4%) included a combination of the maximum height of the navicular (HMAX), maximum length of the cuneiform surface (LMAXCUN), and maximum length of the talar facet (LMAXTAL). The regression equations presented here are useful for the Western Mediterranean populations and offer better alternatives than formulas based on other population groups.

Activity-related sexual dimorphism in Alaskan foragers from Point Hope: Evidences from the upper limb.

Ipiutak (100BCE-500CE) and Tigara (1200 - 1700CE) are two populations from Point Hope, Alaska. As commonly observed in forager communities, it may be expected males and females to have been involved in markedly different daily activities. Nevertheless, activity-related sexual dimorphism in these populations has been scarcely studied. Using humeral diaphyseal cross-sectional properties and forearm rotational efficiency, which are activity-dependent characteristics, we aim to assess differences between sexes and discuss what activities could have triggered them. Our results suggest that in Ipiutak males and females did not differ meaningfully in their cross-sectional properties. Conversely, in Tigara males had a greater rigidity of the entire humeral diaphysis than females, which suggests the existence of greater relative activity levels and more physically demanding tasks, possibly related to hunting activities. Concerning the differences between sexes in the forearm rotational efficiency, in Tigara females rotational efficiency in elbow flexion is maximal in a more supinated position than in males, which leads to an improvement of efficiency in those stages related to manipulation, and so improves the manipulative capacities of the upper limb. These differences in efficiency are caused by a more proximally oriented humeral medial epicondyle in females, which is thus confirmed to be a good feature to assess differences in labor. Therefore females in Tigara probably performed in a daily basis household activities, such as hide processing and other manipulative labors. In Ipiutak, the analysis of forearm rotational efficiency did not reveal differences between sexes. Overall, the results suggest that division of labor in Ipiutak was not as marked as in Tigara, where upper limb skeletal structure supports the idea that both sexes were involved in different daily activities. Nevertheless, the generalized lack of results in Ipiutak could be due to the small sample size, and thus interpretations should be considered with caution.