Male facial cues to physical strength in Europe: Medium-strength preference and higher aggressiveness attribution to the weakest.

OBJECTIVES: The capacity to assess male physical strength from facial cues may be adaptive given health and fitness-related associations with muscular strength. Our study complements recent research on strength-related face perceptions of male Maasai by applying the protocol to male European faces and assessors. METHODS: Five distinct facial morphs calibrated for handgrip strength (HGS) were manufactured with geometric morphometrics performing regressions of the Procrustes shape coordinates on HGS in a sample of 26 European men (18-32 years). Young adult men and women (n = 445) rated these morphs on physical strength, attractiveness, and aggressiveness. RESULTS: Facial morphs calibrated to lower HGS were rated as less strong, less attractive, and more aggressive than those calibrated to higher HGS. Medium levels of HGS were associated with the highest attractiveness ratings. CONCLUSIONS: The rating patterns of physical strength, attractiveness, and aggressiveness for European male facial morphs exhibit similarity to previous ratings of Maasai male faces. Therefore, the current findings corroborate the suggestion of a common mechanism for social attributions based on facial cues to physical strength, modulated by local ecology and societal context.

Perception of strength, attractiveness and aggressiveness of Maasai male faces calibrated to handgrip strength: Evidence from a European sample.

OBJECTIVES: Previous research showed that male and female members of the Maasai from Northern Tanzania judge images of facial morphs calibrated to greater handgrip strength (HGS) higher on strength and attractiveness, but lower on aggressiveness than those calibrated to lower HGS. The accurate assessment of male physical strength from facial information may be adaptive as suggested by the evidence on health and fitness-related benefits linked to high muscular strength. METHODS: This study extends previous work by obtaining European female (n = 220) and male (n = 51) assessments of HGS-calibrated Maasai male faces. Participants rated five facial morphs for strength, attractiveness, and aggressiveness on computer screens. RESULTS: Perceived physical strength increased with morphs calibrated to higher HGS. The lowest and highest HGS morphs were judged lower in attractiveness than the others, and rated aggressiveness decreased in morphs calibrated to higher HGS. CONCLUSIONS: Given the high similarity between the current study findings and those previously reported from intra-population assessments of Maasai faces calibrated to HGS, we suggest that strength and aggressiveness perceptions of facial features associated with male physical strength may be universal. Attractiveness assessments of strength-related information in the faces of (very) strong men were less consistent across populations, possibly attributable to cultural and ecological contexts.

Thirty years of geometric morphometrics: Achievements, challenges, and the ongoing quest for biological meaningfulness.

The foundations of geometric morphometrics were worked out about 30 years ago and have continually been refined and extended. What has remained as a central thrust and source of debate in the morphometrics community is the shared goal of meaningful biological inference through a tight connection between biological theory, measurement, multivariate biostatistics, and geometry. Here we review the building blocks of modern geometric morphometrics: the representation of organismal geometry by landmarks and semilandmarks, the computation of shape or form variables via superimposition, the visualization of statistical results as actual shapes or forms, the decomposition of shape variation into symmetric and asymmetric components and into different spatial scales, the interpretation of various geometries in shape or form space, and models of the association between shape or form and other variables, such as environmental, genetic, or behavioral data. We focus on recent developments and current methodological challenges, especially those arising from the increasing number of landmarks and semilandmarks, and emphasize the importance of thorough exploratory multivariate analyses rather than single scalar summary statistics. We outline promising directions for further research and for the evaluation of new developments, such as "landmark-free" approaches. To illustrate these methods, we analyze three-dimensional human face shape based on data from the Avon Longitudinal Study of Parents and Children (ALSPAC).

Handgrip strength and 2D : 4D in women: homogeneous samples challenge the (apparent) gender paradox.

The length ratio between the second and the fourth digit (2D : 4D) is a retrospective, non-invasive biomarker for prenatal androgen exposure. It was found to be negatively correlated with handgrip strength (HGS) in men, but the evidence for women is mixed. Such studies in women call for increased detection sensitivity. The present study was designed to reduce potential confounding factors, especially age and ethnicity variation. We measured the digit ratios and HGS of 125 healthy women between 19 and 31 years of age from a remote region in Austria. 2D : 4D of both hands was significantly and negatively correlated with HGS (n = 125, right hand: r = -0.255, p = 0.002, left hand: r = -0.206, p = 0.011). Size, direction and significance of correlation coefficients remained stable when statistically controlling for age, body weight, body height, body mass index or hours of exercise per week. This yields theory-consistent evidence that HGS and 2D : 4D are clearly associated in women-when sufficiently reducing genetic variation (confounding 2D : 4D), the ontogenetic environment and age ranges (confounding HGS) in the study population. This finding implies similar organizing effects of prenatal androgens as in men, pointing to a more parsimonious developmental mechanism and a new look into its proximate and ultimate causes.

Correlation of the human pubic symphysis surface with age-at-death: a novel quantitative method based on a bandpass filter.

Age-at-death estimation from skeletal remains typically utilizes the roughness of pubic symphysis articular surfaces. This study presents a new quantitative method adapting a tool from geometric morphometrics, bandpass filtering of partial warp bending energy to extract only age-related changes of the surfaces. The study sample consisted of 440 surface-scanned symphyseal pubic bones from men between 14 and 82 years of age, which were landmarked with 102 fixed and surface semilandmarks. From the original sample, 371 specimens within Procrustes distance of 0.05 of the side-specific average were selected. For this subsample, age was correlated with total bending energy (calculated as summed squared partial warps amplitudes) for a wide range of plausible bandpass filters. For our subsample's 188 right-side surfaces, the correlation between age and bandpass filtered versions of bending energy peaks relatively sharply at r = -0.648 for ages up through 49 years against the first seven partial warp amplitudes only. The finding for left symphyses is similar. The results demonstrate that below the age 50, the symphyseal surface form changes most systematically related to age may be best detected by a lowpass-filtered version of bending energy: signals at the largest geometric scales of roughness rather than its full spectrum. Combining this method with information from other skeletal features could further improve age-at-death estimation based on the symphyseal pubic surface.

Social Perception of Faces: Brain Imaging and Subjective Ratings.

The aim of this study was to investigate how a female face is perceived in terms of its attractiveness, dominance, health, femininity-masculinity, and maturity in direct relation to the body fat percentage (BFP) conveyed by the face. To compare how young adults (ages 18 to 35) respond to different levels of body fat percentage both subjectively and objectively we collected survey ratings and electroencephalography (EEG) data across five different levels of BFP from 40 participants. We adapted the experimental design from a prior behavioral study and used calibrated and morphed female face images of five different BFP levels. The results of the survey are in consensus with the previous study and assessed to be a successful replication. From the EEG data, event-related potentials (ERPs) were extracted from one electrode location (right occipitotemporal brain region) known to be particularly sensitive to face-stimuli. We found statistically significant differences in the amplitudes of the P200 component (194 ms post stimulus onset) between the thickest face and all four other BFP conditions, and in the amplitudes of the N300 component (274 ms post stimulus onset) between the average face and three other BFP conditions. As expected, there were no significant differences among the N170 amplitudes of all five BFP conditions since this ERP component simply reflects the processing of faces in general. From these results, we can infer that holistic face encoding characterized by the N170 component in the right occipitotemporal area is followed by serial evaluative processes, whose categorical and qualitative matrix and spatiotemporal dynamics should be further explored in future studies, especially in relation to the social constructs that were focused on in this study.

Facial aging trajectories: A common shape pattern in male and female faces is disrupted after menopause.

OBJECTIVES: Despite variation in lifestyle and environment, first signs of human facial aging show between the ages of 20-30 years. It is a cumulative process of changes in the skin, soft tissue, and skeleton of the face. As quantifications of facial aging in living humans are still scarce, we set out to study age-related changes in three-dimensional facial shape using geometric morphometrics. MATERIALS AND METHODS: We collected surface scans of 88 human faces (aged 26-90 years) from the coastal town Split (Croatia) and neighboring islands. Based on a geometric morphometric analysis of 585 measurement points (landmarks and semilandmarks), we modeled sex-specific trajectories of average facial aging. RESULTS: Age-related facial shape change was similar in both sexes until around age 50, at which time the female aging trajectory turned sharply. The overall magnitude of facial shape change (aging rate) was higher in women than men, especially in early postmenopause. Aging was generally associated with a flatter face, sagged soft tissue ("broken" jawline), deeper nasolabial folds, smaller visible areas of the eyes, thinner lips, and longer nose and ears. In postmenopausal women, facial aging was best predicted by the years since last menstruation and mainly attributable to bone resorption in the mandible. DISCUSSION: With high spatial and temporal resolution, we were able to extract a shared facial aging pattern in women and men, and its divergence after menopause. This fully quantitative three-dimensional analysis of human facial aging may not only find applications in forensic and ancient human facial reconstructions, but shall include lifestyle and endocrinological measures, and also reach out to studies of social perception.

Associations of physical strength with facial shape in an African pastoralist society, the Maasai of Northern Tanzania.

OBJECTIVES: Previous research has documented associations of physical strength and facial morphology predominantly in men of Western societies. Faces of strong men tend to be more robust, are rounder and have a prominent jawline compared with faces of weak men. Here, we investigate whether the morphometric patterns of strength-face relationships reported for members of industrialized societies can also be found in members of an African pastoralist society, the Maasai of Northern Tanzania. MATERIALS AND METHODS: Handgrip strength (HGS) measures and facial photographs were collected from a sample of 185 men and 120 women of the Maasai in the Ngorongoro Conservation Area. In young-adults (20-29 years; n = 95) and mid-adults (30-50 years; n = 114), we digitized 71 somatometric landmarks and semilandmarks to capture variation in facial morphology and performed shape regressions of landmark coordinates upon HGS. Results were visualized in the form of thin-plate plate spline deformation grids and geometric morphometric morphs. RESULTS: Individuals with higher HGS tended to have wider faces with a lower and broader forehead, a wider distance between the medial canthi of the eyes, a wider nose, fuller lips, and a larger, squarer lower facial outline compared with weaker individuals of the same age-sex group. In mid-adult men, these associations were weaker than in the other age-sex groups. DISCUSSION: We conclude that the patterns of HGS relationships with face shape in the Maasai are similar to those reported from related investigations in samples of industrialized societies. We discuss differences between the present and related studies with regard to knowledge about the causes for age- and sex-related facial shape variation and physical strength associations.

Calibrating facial morphs for use as stimuli in biological studies of social perception.

Studies of human social perception become more persuasive when the behavior of raters can be separated from the variability of the stimuli they are rating. We prototype such a rigorous analysis for a set of five social ratings of faces varying by body fat percentage (BFP). 274 raters of both sexes in three age groups (adolescent, young adult, senior) rated five morphs of the same averaged facial image warped to the positions of 72 landmarks and semilandmarks predicted by linear regression on BFP at five different levels (the average, ±2 SD, ±5 SD). Each subject rated all five morphs for maturity, dominance, masculinity, attractiveness, and health. The patterns of dependence of ratings on the BFP calibration differ for the different ratings, but not substantially across the six groups of raters. This has implications for theories of social perception, specifically, the relevance of individual rater scale anchoring. The method is also highly relevant for other studies on how biological facial variation affects ratings.

Galectin-9 binds to O-glycans on protein disulfide isomerase.

Changes in the T cell surface redox environment regulate critical cell functions, such as cell migration, viral entry and cytokine production. Cell surface protein disulfide isomerase (PDI) contributes to the regulation of T cell surface redox status. Cell surface PDI can be released into the extracellular milieu or can be internalized by T cells. We have found that galectin-9, a soluble lectin expressed by T cells, endothelial cells and dendritic cells, binds to and retains PDI on the cell surface. While endogenous galectin-9 is not required for basal cell surface PDI expression, exogenous galectin-9 mediated retention of cell surface PDI shifted the disulfide/thiol equilibrium on the T cell surface. O-glycans on PDI are required for galectin-9 binding, and PDI recognition appears to be specific for galectin-9, as galectin-1 and galectin-3 do not bind PDI. Galectin-9 is widely expressed by immune and endothelial cells in inflamed tissues, suggesting that T cells would be exposed to abundant galectin-9, in cis and in trans, in infectious or autoimmune conditions.

BMI and WHR Are Reflected in Female Facial Shape and Texture: A Geometric Morphometric Image Analysis.

Facial markers of body composition are frequently studied in evolutionary psychology and are important in computational and forensic face recognition. We assessed the association of body mass index (BMI) and waist-to-hip ratio (WHR) with facial shape and texture (color pattern) in a sample of young Middle European women by a combination of geometric morphometrics and image analysis. Faces of women with high BMI had a wider and rounder facial outline relative to the size of the eyes and lips, and relatively lower eyebrows. Furthermore, women with high BMI had a brighter and more reddish skin color than women with lower BMI. The same facial features were associated with WHR, even though BMI and WHR were only moderately correlated. Yet BMI was better predictable than WHR from facial attributes. After leave-one-out cross-validation, we were able to predict 25% of variation in BMI and 10% of variation in WHR by facial shape. Facial texture predicted only about 3-10% of variation in BMI and WHR. This indicates that facial shape primarily reflects total fat proportion, rather than the distribution of fat within the body. The association of reddish facial texture in high-BMI women may be mediated by increased blood pressure and superficial blood flow as well as diet. Our study elucidates how geometric morphometric image analysis serves to quantify the effect of biological factors such as BMI and WHR to facial shape and color, which in turn contributes to social perception.

Signatures of positive selection in the cis-regulatory sequences of the human oxytocin receptor (OXTR) and arginine vasopressin receptor 1a (AVPR1A) genes.

BACKGROUND: The evolutionary highly conserved neurohypophyseal hormones oxytocin and arginine vasopressin play key roles in regulating social cognition and behaviours. The effects of these two peptides are meditated by their specific receptors, which are encoded by the oxytocin receptor (OXTR) and arginine vasopressin receptor 1a genes (AVPR1A), respectively. In several species, polymorphisms in these genes have been linked to various behavioural traits. Little, however, is known about whether positive selection acts on sequence variants in genes influencing variation in human behaviours. RESULTS: We identified, in both neuroreceptor genes, signatures of balancing selection in the cis-regulative acting sequences such as transcription factor binding and enhancer sequences, as well as in a transcriptional repressor sequence motif. Additionally, in the intron 3 of the OXTR gene, the SNP rs59190448 appears to be under positive directional selection. For rs59190448, only one phenotypical association is known so far, but it is in high LD' (>0.8) with loci of known association; i.e., variants associated with key pro-social behaviours and mental disorders in humans. CONCLUSIONS: Only for one SNP on the OXTR gene (rs59190448) was a sign of positive directional selection detected with all three methods of selection detection. For rs59190448, however, only one phenotypical association is known, but rs59190448 is in high LD' (>0.8), with variants associated with important pro-social behaviours and mental disorders in humans. We also detected various signatures of balancing selection on both neuroreceptor genes.

The morphometrics of "masculinity" in human faces.

In studies of social inference and human mate preference, a wide but inconsistent array of tools for computing facial masculinity has been devised. Several of these approaches implicitly assumed that the individual expression of sexually dimorphic shape features, which we refer to as maleness, resembles facial shape features perceived as masculine. We outline a morphometric strategy for estimating separately the face shape patterns that underlie perceived masculinity and maleness, and for computing individual scores for these shape patterns. We further show how faces with different degrees of masculinity or maleness can be constructed in a geometric morphometric framework. In an application of these methods to a set of human facial photographs, we found that shape features typically perceived as masculine are wide faces with a wide inter-orbital distance, a wide nose, thin lips, and a large and massive lower face. The individual expressions of this combination of shape features--the masculinity shape scores--were the best predictor of rated masculinity among the compared methods (r = 0.5). The shape features perceived as masculine only partly resembled the average face shape difference between males and females (sexual dimorphism). Discriminant functions and Procrustes distances to the female mean shape were poor predictors of perceived masculinity.

Microbe-Host Interactions are Positively and Negatively Regulated by Galectin-Glycan Interactions.

Microbe-host interactions are complex processes that are directly and indirectly regulated by a variety of factors, including microbe presentation of specific molecular signatures on the microbial surface, as well as host cell presentation of receptors that recognize these pathogen signatures. Cell surface glycans are one important class of microbial signatures that are recognized by a variety of host cell lectins. Host cell lectins that recognize microbial glycans include members of the galectin family of lectins that recognize specific glycan ligands on viruses, bacteria, fungi, and parasites. In this review, we will discuss the ways that the interactions of microbial glycans with host cell galectins positively and negatively regulate pathogen attachment, invasion, and survival, as well as regulate host responses that mitigate microbial pathogenesis.

Variation at genes influencing facial morphology are not associated with developmental imprecision in human faces.

Facial asymmetries are commonly used as a proxy for human developmental imprecision resulting from inbreeding, and thus reduced genetic heterozygosity. Several environmental factors influence human facial asymmetry (e.g., health care, parasites), but the generalizability of findings on genetic stressors has been limited in humans by sample characteristics (island populations, endogamy) and indirect genetic assessment (inference from pedigrees). In a sample of 3215 adult humans from the Rotterdam Study, we therefore studied the relationship of facial asymmetry, estimated from nine mid-facial landmarks, with genetic variation at 102 single nucleotide polymorphism (SNP) loci recently associated with facial shape variation. We further tested whether the degree of individual heterozygosity is negatively correlated with facial asymmetry. An ANOVA tree regression did not identify any SNP relating to either fluctuating asymmetry or total asymmetry. In a general linear model, only age and sex--but neither heterozygosity nor any SNP previously reported to covary with facial shape--was significantly related to total or fluctuating asymmetry of the midface. Our study does not corroborate the common assumption in evolutionary and behavioral biology that morphological asymmetries reflect heterozygosity. Our results, however, may be affected by a relatively small degree of inbreeding, a relatively stable environment, and an advanced age in the Rotterdam sample. Further large-scale genetic studies, including gene expression studies, are necessary to validate the genetic and developmental origin of morphological asymmetries.

Body fat and facial shape are correlated in female adolescents.

OBJECTIVES: Relative body weight is not only an important indicator for health and reproductive condition, but also subject to stereotypes and stigmatization. It can be reliably assessed from adult faces alone, yet the facial correlates, especially in adolescents, remain largely unidentified. This study was designed to determine the facial features of adolescent girls that change with body fat proportion using a modern, comprehensive technique for shape analysis. METHODS: Standardized frontal facial photographs of 22 Caucasian female adolescents (mean age 15.8 ± 2.7 years) were taken, and body height, body weight, and body fat proportion measured. Seventy-two somatometric measurement points were digitized on each photograph and their Cartesian coordinates regressed onto body fat proportion. Geometric morphometrics also enabled visualizing the statistical results as shapes. RESULTS: Body fat proportion explained 8.7% of the facial shape variation (10,000 permutations, P = 0.047). Girls with high body fat had a relatively rounder and larger lower face, relatively smaller eyes, and a shorter and wider nose, fuller lips and downturned corners of the mouth. Low body fat was associated with a more angular lower face and a pointier chin, relatively larger eyes and a longer nose. The lips were wider and thinner, the corners of the mouth upturned. CONCLUSION: Body fat proportion is a substantial factor in facial shape variation of female adolescents. The potential influence of the corresponding facial features on social perception is discussed. Prospects for future research including novel possibilities for stimuli design (GM morphs) are highlighted.

A nonionic inhibitor with high specificity for the UDP-Gal donor binding site of human blood group B galactosyltransferase: design, synthesis, and characterization.

9-(5-O-α-D-galactopyranosyl)-D-arabinityl-1,3,7-trihydropurine-2,6,8-trione (1) was designed and synthesized as a nonionic inhibitor for the donor binding site of human blood group B galactosyltransferase (GTB). Enzymatic characterization showed 1 to be extremely specific, as the highly homologous human N-acetylgalactosaminyltransferase (GTA) is not inhibited. The binding epitope of 1 demonstrates a high involvement of the arabinityl linker, whereas the galactose residue is only making contact to the protein via its C-2 site, which is very important for the discrimination between galactose and N-acetylgalactosamine, the substrate transferred by GTA. The approach can generate highly specific glycosyltransferase inhibitors.

Second-to-fourth digit ratio and facial shape in boys: the lower the digit ratio, the more robust the face.

During human ontogeny, testosterone has powerful organizational and activational effects on the male organism. This has led to the hypothesis that the prenatal environment (as studied through the second-to-fourth digit ratio, 2D : 4D) is not only associated with robust adult male faces that are perceived as dominant and masculine, but also that there is an activational step during puberty. To test the latter, we collected digit ratios and frontal photographs of right-handed Caucasian boys (aged 4-11 years) along with age, body height and body weight. Using geometric morphometrics, we show a significant relationship between facial shape and 2D : 4D before the onset of puberty (explaining 14.5% of shape variation; p = 0.014 after 10 000 permutations, n = 17). Regression analyses depict the same shape patterns as in adults, namely that the lower the 2D : 4D, the smaller and shorter the forehead, the thicker the eyebrows, the wider and shorter the nose, and the larger the lower face. Our findings add to previous evidence that certain adult male facial characteristics that elicit attributions of masculinity and dominance are determined very early in ontogeny. This has implications for future studies in various fields ranging from social perception to life-history strategies.

A new concept for glycosyltransferase inhibitors: nonionic mimics of the nucleotide donor of the human blood group B galactosyltransferase.

Glycosyltransferases play an important role in the formation of oligosaccharides and glycoconjugates. To find suitable and selective inhibitors for this class of enzymes is still challenging. Here, we describe a novel concept that allows the design of inhibitors based on the structure of the donor substrate binding pocket. As a first step we describe the design, synthesis and analysis of inhibitors of the human blood group B galactosyltransferase (GTB). This enzyme served as a model system to study the concept, which can be used for easy access of glycosyltransferase inhibitors in general. In silico docking of bicyclic heteroaromatic ligands to GTB and experimental verification of binding affinities by saturation transfer difference NMR (STD NMR) spectroscopy gave 9-N-pentityl uric acid derivatives as non-ionic mimics of UDP. Two derivatives were synthesized and showed inhibitory activity for GTB as determined by competitive STD NMR experiments and by a radiolabeled enzyme assay.

Leptin locally synthesized in carotid atherosclerotic plaques could be associated with lesion instability and cerebral emboli.

BACKGROUND: Unstable carotid plaques cause cerebral emboli. Leptin promotes atherosclerosis and vessel wall remodeling. We hypothesized that carotid atherosclerotic lesion instability is associated with local leptin synthesis. METHODS AND RESULTS: Carotid endarterectomy plaques from symptomatic (n=40) and asymptomatic patients with progressive stenosis (n=38) were analyzed for local expression of leptin, tumor necrosis factor (TNF)-α, and plasminogen activator inhibitor type 1. All lesions exhibited advanced atherosclerosis inclusive of thick- and thin-cap fibroatheromas or lesion rupture. Symptomatic lesions exhibited more plaque ruptures and macrophage infiltration (P=0.001 and P=0.05, respectively). Symptomatic plaques showed preferential leptin, TNF-α, and plasminogen activator inhibitor type 1 transcript (P=0.03, P=0.04, and P=0.05, respectively). Leptin mRNA and antigen in macrophages and smooth muscle cells were confirmed by in situ hybridization and immunohistochemistry. Plasma leptin levels were not significantly different between groups (P=1.0), whereas TNF-α was significantly increased in symptomatic patients (P=0.006). Human aortic smooth muscle cell culture stimulated by TNF-α, lipopolysaccharide, or lipoteichoic acid revealed 6-, 6.7-, and 6-fold increased secreted leptin antigen, respectively, at 72 hours (P<0.05). CONCLUSIONS: Neurologically symptomatic patients overexpress leptin mRNA and synthesize leptin protein in carotid plaque macrophages and smooth muscle cells. Local leptin induction, presumably by TNF-α, could exert paracrine or autocrine effects, thereby contributing to the pathogenesis of lesion instability. CLINICAL TRIAL REGISTRATION: URL: www.Clinicaltrials.gov. Unique identifier: NCT00449306.