African perceptions of female attractiveness

Little is known about mate choice preferences outside Western, educated, industrialised, rich and democratic societies, even though these Western populations may be particularly unrepresentative of human populations. To our knowledge, this is the first study to test which facial cues contribute to African perceptions of African female attractiveness and also the first study to test the combined role of facial adiposity, skin colour (lightness, yellowness and redness), skin homogeneity and youthfulness in the facial attractiveness preferences of any population. Results show that youthfulness, skin colour, skin homogeneity and facial adiposity significantly and independently predict attractiveness in female African faces. Younger, thinner women with a lighter, yellower skin colour and a more homogenous skin tone are considered more attractive. These findings provide a more global perspective on human mate choice and point to a universal role for these four facial cues in female facial attractiveness.Publisher PDFPeer reviewe

Facial width-to-height ratio relates to alpha status and assertive personality in capuchin monkeys

Social dominance hierarchies play a pivotal role in shaping the behaviour of many species, and sex differences within these hierarchies often exist. To date, however, few physical markers of dominance have been identified. Such markers would be valuable in terms of understanding the etiology of dominant behaviour and changes in social hierarchies over time. Animals may also use such traits to evaluate the potential dominance of others relative to themselves (i.e. a physical “cue”). Facial width-to-height ratio (fWHR), for example, has been suggested as a cue to dominance in humans, with links to both dominant behaviour and the perception of dominance in other individuals. Whether this association is present in non-human animals is currently not known. Therefore, here we examine within-species links between fWHR and dominant behaviour in 64 brown capuchin monkeys (Sapajus spp.) aged between 2 and 40 years. fWHR was positively associated with alpha status and with a dimensional rating of assertive personality in both males and females. Moreover, fWHR showed significant sexual dimorphism in adults but not juveniles, suggesting a developmental change may occur during puberty. In a sub-sample, sex differences were mediated by weight, suggesting fWHR dimorphism does not exceed what would be expected by differences in body weight. This is the first report of an association between face shape and behaviour in a non-human species. Results are discussed in terms of the role that face-behaviour associations might play within capuchin societies, and the possible selective forces that might have led to the evolution of fWHR-dominance associations in humans

The role of sexually dimorphic skin colour and shape in attractiveness of male faces

This research was supported by funding from Foundation for Science and Technology (FCT) and the POPH/FSE Program (grant reference SFRH/BD/77592/2011).Evidence for attraction to sexually dimorphic features in male faces is inconsistent in the literature. Mixed results regarding facial masculinity and male attractiveness may arise partly from different influences of face shape and face colouration depending on whether colour was controlled. Recent research suggests that masculinity in face colour, namely darker skin, and femininity in shape are attractive in male faces. Here we examine the influence of sexual dimorphism in skin colour and face shape on attractiveness in 3 experiments. We allowed female participants to manipulate male and female face images along axes of sexual dimorphism in skin colour and/or shape in order to optimise attractiveness. Participants searching for the most attractive appearance chose to masculinise the colour of male faces more than the colour of female faces (although not reaching significance in Experiment 3; p = .16). We found a clear preference for feminine shape in male faces supporting predictions of recent research. These results help to clarify the influence of facial masculinity in women’s attractiveness preferences.PostprintPeer reviewe

Facial width-to-height ratio relates to alpha status and assertive personality in capuchin monkeys

Social dominance hierarchies play a pivotal role in shaping the behaviour of many species, and sex differences within these hierarchies often exist. To date, however, few physical markers of dominance have been identified. Such markers would be valuable in terms of understanding the etiology of dominant behaviour and changes in social hierarchies over time. Animals may also use such traits to evaluate the potential dominance of others relative to themselves (i.e. a physical “cue”). Facial width-to-height ratio (fWHR), for example, has been suggested as a cue to dominance in humans, with links to both dominant behaviour and the perception of dominance in other individuals. Whether this association is present in non-human animals is currently not known. Therefore, here we examine within-species links between fWHR and dominant behaviour in 64 brown capuchin monkeys (Sapajus spp.) aged between 2 and 40 years. fWHR was positively associated with alpha status and with a dimensional rating of assertive personality in both males and females. Moreover, fWHR showed significant sexual dimorphism in adults but not juveniles, suggesting a developmental change may occur during puberty. In a sub-sample, sex differences were mediated by weight, suggesting fWHR dimorphism does not exceed what would be expected by differences in body weight. This is the first report of an association between face shape and behaviour in a non-human species. Results are discussed in terms of the role that face-behaviour associations might play within capuchin societies, and the possible selective forces that might have led to the evolution of fWHR-dominance associations in humans

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Investigating facial correlates of dominance and trustworthiness : their biological underpinnings and perceptual properties

Information conveyed by the face can be used in social encounters to make fast decisions about another person. Recently, a new model of face perception has been postulated (Oosterhof & Todorov, 2009) suggesting that there are two basic judgements that underlie person evaluations from faces: dominance and trustworthiness. But on the basis of which cues are these judgements made, and do these cues have biological validity? In this thesis I investigate two putative facial cues to dominance and trustworthiness; namely, facial width-to-height ratio (fWHR) and skin yellowness. In men, fWHR has previously been linked to aggressive and dominant behaviour as well as the perception of these traits. Here I show that a more positive dominance related trait (achievement striving) is also related to this metric, indicating a general association of fWHR to dominance rather than simple aggression. Furthermore, I explore the biological underpinnings of this metric by showing 1) that contrary to initial findings and predictions fWHR is not sexually dimorphic, and 2) that fWHR is associated with testosterone, indicating a physiological link between appearance and behaviour. Additionally, I extend current work on fWHR by showing that it acts as a cue to dominance not only in humans but also in non-human primates. The second part of the current thesis firstly identifies skin yellowness as a novel cue used in trustworthiness judgement. It shows that this putatively carotenoid induced cue to current health is not only employed in mate choice context but may also play an important role in other social context and in judgements of who poses an adequate partner for social interactions. Secondly, I show that skin yellowness is inversely related to testosterone levels in men, showing for the first time an association between this carotenoid induced signal and testosterone in humans thereby extending previous work in birds

Functional architecture of visual emotion recognition ability: a latent variable approach

Emotion recognition has been a focus of considerable attention for several decades. However, despite this interest, the underlying structure of individual differences in emotion recognition ability has been largely overlooked and thus is poorly understood. For example, limited knowledge exists concerning whether recognition ability for one emotion (e.g., disgust) generalizes to other emotions (e.g., anger, fear). Furthermore, it is unclear whether emotion recognition ability generalizes across modalities, such that those who are good at recognizing emotions from the face, for example, are also good at identifying emotions from nonfacial cues (such as cues conveyed via the body). The primary goal of the current set of studies was to address these questions through establishing the structure of individual differences in visual emotion recognition ability. In three independent samples (Study 1: n=640; Study 2: n=389; Study 3: n=303), we observed that the ability to recognize visually presented emotions is based on different sources of variation: a supramodal Emotion-General factor, supramodal Emotion-Specific factors, and Face-And Within-Modality Emotion-Specific factors. In addition, we found evidence that general intelligence and alexithymia were associated with supramodal emotion recognition ability. Autism-Like traits, empathic concern, and alexithymia were independently associated with Face-Specific emotion recognition ability. These results (a) provide a platform for further individual differences research on emotion recognition ability, (b) indicate that differentiating levels within the architecture of emotion recognition ability is of high importance, and (c) show that the capacity to understand expressions of emotion in others is linked to broader affective and cognitive processes

Telling facial metrics:facial width is associated with testosterone levels in men

High facial width-to-height ratio (fWHR) has been associated with a cluster of behavioural traits in men, including aggression and status-striving. This association between face structure and behaviour may be caused by testosterone. Here we investigated the relationship of both baseline and reactive testosterone levels to fWHR. In addition, we investigated the link between testosterone and three well-characterised sexually dimorphic facial metrics. Testosterone was measured in one sample of males (n. = 185) before and after a speed-dating event. An additional sample provided only baseline testosterone measures (n. = 92). fWHR was positively associated with testosterone reactions to potential mate exposure and marginally associated with baseline testosterone in Sample 1. We found a positive association with baseline testosterone and fWHR in Sample 2. In addition, face-width-to-lower-height ratio was positively associated with testosterone in both samples, suggesting that, in particular, facial width (scaled by two measures of facial height) is associated with testosterone. Importantly, our results also indicate that there is no association between adult testosterone and the sexual dimorphism of face shape. Thus, while our findings question the status of sexual dimorphism as a proxy measure of testosterone, they do provide evidence that testosterone is linked to fWHR and might underlie the relationship between fWHR and behaviour. © 2013 Elsevier Inc

Ethical judgement and ethical authority

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