Exploring sexual dimorphism of the modern human talus through geometric morphometric methods

Sex determination is a pivotal step in forensic and bioarchaeological fields. Generally, scholars focus on metric or qualitative morphological features, but in the last few years several contributions have applied geometric-morphometric (GM) techniques to overcome limitations of traditional approaches. In this study, we explore sexual dimorphism in modern human tali from three early 20th century populations (Sassari and Bologna, Italy; New York, USA) at intra- and interspecific population levels using geometric morphometric (GM) methods. Statistical analyses were performed using shape, form, and size variables. Our results do not show significant differences in shape between males and females, either considering the pooled sample or the individual populations. Differences in talar morphology due to sexual dimorphism are mainly related to allometry, i.e. size-related changes of morphological traits. Discriminant function analysis using form space Principal Components and centroid size correctly classify between 87.7% and 97.2% of the individuals. The result is similar using the pooled sample or the individual population, except for a diminished outcome for the New York group (from 73.9% to 78.2%). Finally, a talus from the Bologna sample (not included in the previous analysis) with known sex was selected to run a virtual resection, followed by two digital reconstructions based on the mean shape of both the pooled sample and the Bologna sample, respectively. The reconstructed talus was correctly classified with a Ppost between 99.9% and 100%, demonstrating that GM is a valuable tool to cope with fragmentary tali, which is a common occurrence in forensic and bioarchaeological contexts

Gender recognition from facial images: Two or three dimensions?

© 2016 Optical Society of America. This paper seeks to compare encoded features from both two-dimensional (2D) and three-dimensional (3D) face images in order to achieve automatic gender recognition with high accuracy and robustness. The Fisher vector encoding method is employed to produce 2D, 3D, and fused features with escalated discriminative power. For 3D face analysis, a two-source photometric stereo (PS) method is introduced that enables 3D surface reconstructions with accurate details as well as desirable efficiency. Moreover, a 2D + 3D imaging device, taking the two-source PS method as its core, has been developed that can simultaneously gather color images for 2D evaluations and PS images for 3D analysis. This system inherits the superior reconstruction accuracy from the standard (three or more light) PS method but simplifies the reconstruction algorithm as well as the hardware design by only requiring two light sources. It also offers great potential for facilitating human computer interaction by being accurate, cheap, efficient, and nonintrusive. Ten types of low-level 2D and 3D features have been experimented with and encoded for Fisher vector gender recognition. Evaluations of the Fisher vector encoding method have been performed on the FERET database, Color FERET database, LFW database, and FRGCv2 database, yielding 97.7%, 98.0%, 92.5%, and 96.7% accuracy, respectively. In addition, the comparison of 2D and 3D features has been drawn from a self-collected dataset, which is constructed with the aid of the 2D + 3D imaging device in a series of data capture experiments. With a variety of experiments and evaluations, it can be proved that the Fisher vector encoding method outperforms most state-of-the-art gender recognition methods. It has also been observed that 3D features reconstructed by the two-source PS method are able to further boost the Fisher vector gender recognition performance, i.e., up to a 6% increase on the self-collected database

Exploring sexual dimorphism of the modern human talus through geometric morphometric methods

Sex determination is a pivotal step in forensic and bioarchaeological fields.Generally,scholars focus on metric or qualitative morphological features,but in the last few years several contributions have applied geometric-morphometric (GM) techniques to overcome limitations of traditional approaches. In this study,we explore sexual dimorphism in modern human tali from three early 20th century populations (Sassari and Bologna, Italy; NewYork, USA) at intra- and interspecific population levels using geometric morphometric (GM) methods.Statistical analyses were performed using shape,form,and size variables.Our results do not show significant differences in shape between males and females, either considering the pooled sample or the individual populations. Differences in talar morphology due to sexual dimorphism are mainly related to allometry, i.e. size-related changes of morphological traits. Discriminant function analysis using form space Principal Components and centroid size correctly classify between 87.7% and 97.2% of the individuals.The result is similar using the pooled sample the individual population, except for a diminished outcome for the New York group (from 73.9% to 78.2%). Finally, a talus from the Bologna sample (not included in the previous analysis) with known sex was selected to run a virtual resection, followed by two digital reconstructions based on the mean shape of both the pooled sample and the Bologna sample, respectively.The reconstructed talus was correctly classified with a P post between 99.9%and100%,demonstrating that GM is a valuable tool to cope with fragmentary tali,which is a common occurrence in forensic and bioarchaeological context

The spectacular human nose: an amplifier of individual quality?

Amplifiers are signals that improve the perception of underlying differences in quality. They are cost free and advantageous to high quality individuals, but disadvantageous to low quality individuals, as poor quality is easier perceived because of the amplifier. For an amplifier to evolve, the average fitness benefit to the high quality individuals should be higher than the average cost for the low quality individuals. The human nose is, compared to the nose of most other primates, extraordinary large, fragile and easily broken—especially in male–male interactions. May it have evolved as an amplifier among high quality individuals, allowing easy assessment of individual quality and influencing the perception of attractiveness? We tested the latter by manipulating the position of the nose tip or, as a control, the mouth in facial pictures and had the pictures rated for attractiveness. Our results show that facial attractiveness failed to be influenced by mouth manipulations. Yet, facial attractiveness increased when the nose tip was artificially centered according to other facial features. Conversely, attractiveness decreased when the nose tip was displaced away from its central position. Our results suggest that our evaluation of attractiveness is clearly sensitive to the centering of the nose tip, possibly because it affects our perception of the face’s symmetry and/or averageness. However, whether such centering is related to individual quality remains unclear

Three Dimensional Nonlinear Statistical Modeling Framework for Morphological Analysis

This dissertation describes a novel three-dimensional (3D) morphometric analysis framework for building statistical shape models and identifying shape differences between populations. This research generalizes the use of anatomical atlases on more complex anatomy as in case of irregular, flat bones, and bones with deformity and irregular bone growth. The foundations for this framework are: 1) Anatomical atlases which allow the creation of homologues anatomical models across populations; 2) Statistical representation for output models in a compact form to capture both local and global shape variation across populations; 3) Shape Analysis using automated 3D landmarking and surface matching. The proposed framework has various applications in clinical, forensic and physical anthropology fields. Extensive research has been published in peer-reviewed image processing, forensic anthropology, physical anthropology, biomedical engineering, and clinical orthopedics conferences and journals. The forthcoming discussion of existing methods for morphometric analysis, including manual and semi-automatic methods, addresses the need for automation of morphometric analysis and statistical atlases. Explanations of these existing methods for the construction of statistical shape models, including benefits and limitations of each method, provide evidence of the necessity for such a novel algorithm. A novel approach was taken to achieve accurate point correspondence in case of irregular and deformed anatomy. This was achieved using a scale space approach to detect prominent scale invariant features. These features were then matched and registered using a novel multi-scale method, utilizing both coordinate data as well as shape descriptors, followed by an overall surface deformation using a new constrained free-form deformation. Applications of output statistical atlases are discussed, including forensic applications for the skull sexing, as well as physical anthropology applications, such as asymmetry in clavicles. Clinical applications in pelvis reconstruction and studying of lumbar kinematics and studying thickness of bone and soft tissue are also discussed

How has the morphology of the human mandible varied in response to the dietary changes that have occurred in Britain between the Neolithic and Post-Medieval periods?

Unlike cranial morphology, human mandibular morphology has been found to be influenced primarily by environmental as opposed to genetic factors. Previous research has demonstrated that significant morphological changes have occurred in the mandible during the Agricultural and Industrial Revolutions when widespread dietary changes occurred, and diet became softer. During this time the size of the mandible decreased, and mandible morphology became more gracile. This research however has typically focussed on comparisons between two time periods associated with a large dietary transition. For this reason, it is not known if the reported changes in mandible morphology represent a consistent reduction in mandibular robusticity or rather fluctuation between periods associated with dietary variability. Furthermore, it is unclear how susceptible the mandible is to smaller dietary changes. The aim of this thesis is to investigate how responsive mandible morphology is to the dietary changes that have occurred in Britain from the Neolithic through to the Post-Medieval periods. It is hypothesised that mandible morphology is responsive enough to mechanical stimuli that more minor dietary changes will also result in morphological variation. Results indicated that in general mandible morphology became increasingly gracile over time, while more pronounced morphological changes are associated with major dietary transitions such as the intensification of agriculture and the Industrial Revolution. Moreover, significant increases in gracilisation occurred between the Anglo-Saxon and Medieval period, potentially indicating that the dietary changes that occurred during the Industrial Revolution were more gradual than previous research has indicated. In addition to the more prominent morphological changes, smaller morphological fluctuations occurred such as during the Roman occupation. It is concluded that the mandible is more responsive to smaller dietary changes than demonstrated by previous research and the morphological variation associated with these major dietary transitions may not have been as simple or rapid as previously assumed

Comparison of Male and Female Rib Sternal Ends and the Effects of Aging using Elliptical Fourier Analysis

Sex and age make up two of the main tenets of the biological profile. Most anthropologists would argue that sex is one of the most important aspects of the profile. When creating a biological profile, the first step is to estimate sex of the individual because this can affect age estimation using the os coxa or estimations of stature. Past studies have noted that even though ribs carry out the same function in males and females there are morphological differences that can affect age estimation using the ribs. This study uses Elliptical Fourier analysis to compare differences in overall shape of the male and female sternal rib end. It also explores how the shape of the sternal end of the rib is affected by skeletal aging processes. As other studies have noted the rate and pattern of costal cartilage ossification seem to exhibit trends based on sex and age of the individuals. For this reason, the amount or rate of ossification and ossification patterning were also explored. The results showed that for all features analyzed, age and sex were found to be key influencers with varying degrees. In the case of costal cartilage ossification this study found that rate of ossification was based more on age while sex was more of an influence for differences in ossification patterning on the sternal end of the rib. Further analysis also revealed that the degree that sex or age influenced the shape of the sternal was dependent on which rib was used, e.g., rib 1 or rib 5