Association between Facial Metrics and Mate Rejection for Long-Term Relationship by Heterosexual Men
Luiza Penha PinheiroLuis Carlos Pereira MonteiroLeonardo Dutra HenriquesGivago da Silva SouzaAna Catarina MirandaMarcelo Fernandes CostaAlda Loureiro Henriques
0
Citation
55
Reference
10
Related Paper
Abstract:
Investigations on mate choice in humans frequently report preferences, but there is little knowledge about what is important for rejection by a potential mate. The present study aims to verify if facial asymmetry and facial disharmony have an influence on mate rejection by men. We hypothesized that more asymmetric and disharmonious faces would be more rejected. For this purpose, photographs of women’s faces were presented in pairs by self-declared heterosexual men. It was requested they reject one of the faces as a potential mate for a long-term relationship. Women’s faces were also analyzed to measure facial asymmetry and facial disharmony. We used a linear mixed model to evaluate the effect of the cited metrics on each face’s number of rejections. We found that the female metrics influenced mate rejection only if associated with male age and income. The older participants rejected female partners with asymmetric faces. We suggest that aging makes men more demanding in mate choices, at least considering facial asymmetry. We concluded that rejection could be a key variable in mate choice studies, but further research is needed to clarify its effects.Keywords:
Facial symmetry
Fluctuating asymmetry
Abstract Asymmetry has been demonstrated to play a role in signalling systems such as sexual selection and pollination, with receivers showing a preference for symmetrical signals. Large signals often have the smallest degree of asymmetry, a finding that is consistent with signal asymmetry being condition-dependent. The kind of asymmetry displayed by signals was supposed or shown to be fluctuating asymmetry, and signals revealing individual differences in the ability to stabilize developmental processes, despite a hostile developmental environment, was supposed to be the basis for the preference for symmetric signals. Recently, it has been suggested that condition-dependent signals display antisymmetry rather than fluctuating asymmetry, based on analyses of the relationship between asymmetry and mean length of the left and the right character in a few published graphs of absolute asymmetry of signals. Here I demonstrate on the basis of a much larger number of data sets, including those previously published, that the previous results are biased because of the methods used for the analyses, and that characters with condition-dependent asymmetry show fluctuating asymmetry rather than antisymmetry. In particular, frequency distributions of signed left-minus-right character values display leptokurtosis, as predicted if asymmetry distributions reflected individual differences in developmental precision, rather than platykurtosis. Platykurtosis is predicted if the traits are antisymmetric. The preponderance of leptokurtic distributions is consistent with recent modelling showing that inherent differences in the ability of individuals to control developmental processes invariably leads to leptokurtic distributions of signed left-minus-right character values.
Antisymmetry
Fluctuating asymmetry
Kurtosis
Cite
Citations (10)
Nachman and Heller recently suggested that previous estimates of the relative magnitude of fluctuating asymmetry in morphological characters have been biased because non-linear relationships between asymmetry and size have not been considered. This suggestion cannot generally be very important because (1) inclusion of a non-linear size term in regression models relating fitness components to asymmetry does not change the general conclusion that asymmetry is an important predictor of fitness components, and (2) experimental studies uncoupling the relationship between asymmetry and size have generally found significant effects of asymmetry independent of body size on mating success and locomotion.
Fluctuating asymmetry
Cite
Citations (21)
It has been postulated that levels of fluctuating asymmetry in human faces may be negatively related to components of fitness such as parasite-resistance; hence potential mates with low levels of asymmetry may appear more attractive. However, previous investigations of the relationship between asymmetry and facial attractiveness have confounded manipulations of asymmetry with facial 'averageness' and mean trait size. In this experiment we performed a manipulation that altered asymmetry within a face without altering the mean size of facial features. These faces were then rated on attractiveness. Contrary to what was predicted, faces that were made more symmetrical were perceived as being less attractive. These results do not support the hypothesis that attractiveness is related to low levels of fluctuating asymmetry. The observed positive relationship between asymmetry and facial attractiveness may be because certain facial features (including those contributing to attractiveness) in fact show directional asymmetry or antisymmetry. Our manipulations thus render naturally asymmetric features symmetrical. This may make symmetric faces less attractive because of the reduction of natural directional asymmetries, perhaps making the faces appear unemotional. The role of fluctuating asymmetries alone in assessments of facial beauty is still unknown, although this experiment suggests fluctuating asymmetry is relatively unimportant compared with directional asymmetry.
Fluctuating asymmetry
Facial symmetry
Trait
Facial attractiveness
Antisymmetry
Physical attractiveness
Cite
Citations (186)
Facial symmetry is an important component of attractiveness. However, functional symmetry is favorable to aesthetic symmetry. In addition, fluctuating asymmetry is more natural and common, even if patients find such asymmetry to be noticeable. However, fluctuating asymmetry remains difficult to define. Several studies have shown that a certain level of asymmetry could generate an unfavorable image. A natural profile is favorable to perfect mirror-image profile, and images with canting and differences less than 3°-4° and 3-4 mm, respectively, are generally not recognized as asymmetry. In this study, a questionnaire survey among 434 medical students was used to evaluate photos of Asian women. The students preferred original images over mirror images. Facial asymmetry was noticed when the canting and difference were more than 3° and 3 mm, respectively. When a certain level of asymmetry is recognizable, correcting it can help to improve social life and human relationships. Prior to any operation, the anatomical component for noticeable asymmetry should be understood, which can be divided into hard tissues and soft tissue. For diagnosis, two-and three-dimensional (3D) photogrammetry and radiometry are used, including photography, laser scanner, cephalometry, and 3D computed tomography. Keywords: Facial asymmetry / Three dimensional image / Face
Facial symmetry
Fluctuating asymmetry
Cite
Citations (69)
Fluctuating asymmetry
Trait
Ornaments
Cite
Citations (381)
We tested seven hypotheses regarding the mechanisms by which fluctuating asymmetry (FA) originates. We did this by analyzing data on four bilateral characters measured repeatedly during the development of individual domestic fowl. Immediately posthatching, there was substantial directional asymmetry, which rapidly decreased. We detected FA at significant levels in all characters in the majority of our measurements over the remainder of development. We also examined the effects of known environmental stressors (food and density stress) on levels of FA. At the levels we examined, changes in these stressors did not alter the degree of asymmetry we found in fowl. Time series of asymmetry for individuals did not exhibit regular oscillations, as much of the relevant literature predicts. Asymmetry levels reflected the combined effects of developmental noise, which was random in degree and direction, and feedback processes, which decreased asymmetry by altering growth rates on both sides of the body. Our findings best fit the predictions of the residual asymmetry and compensatory growth hypotheses, which suggest that levels of asymmetry reflect only recent growth history.
Fluctuating asymmetry
Fowl
Degree (music)
Stressor
Environmental stress
Cite
Citations (74)
Facial symmetry
Mirroring
Cite
Citations (18)
Fluctuating asymmetry
Trait
Ornaments
Cite
Citations (289)
Fluctuating asymmetry has received considerable recent attention in evolutionary biology as these small developmental asymmetries can be related to biological fitness and, hence, could be used as a visual cue (or signal) of quality among individuals. The ability of signal receivers to detect and respond to small asymmetries is a fundamental assumption of the symmetry–signalling hypothesis, but has not been experimentally investigated. In this study I have investigated the perceptual threshold to detect and respond to paired–bar length asymmetry in a common bird, the European starling Sturnus vulgaris, by means of operant–learning techniques. The threshold indicates how large the length asymmetry must be to be reliably discriminated from symmetry; birds could not detect an asymmetry of 1.25%. In nature, many asymmetries can be smaller than 1.25%, hence this initial study suggests that caution should be used when trying to invoke symmetry–signalling in natural populations.
Sturnus
Fluctuating asymmetry
Starling
Signalling
SIGNAL (programming language)
Cite
Citations (40)
Bilateral asymmetry in the transverse processes (TP) of the cervical vertebrae in domestic chickens was investigated. The asymmetry was classified into two categories; directional and fluctuating. The directional asymmetry was measured by the difference between the lengths of the two TP, that is, left minus right. The fluctuating asymmetry, however, was defined as asymmetry due to chance fluctuation in the development of left and right TP and was measured by the bilateral asymmetry remaining after subtraction of the average directional asymmetry of each strain. If the degree of fluctuating asymmetry in a single bird is a, then a=|(left-right)-average(left-right)|. Since a was found not to distribute normally, it has been transformed to A=log10[(a+0.1)2]. The birds investigated were 16-month old White Leghorn females of 6 inbred, one closed and 5 F1 hybrid strains. The lengths of the left and right TP (4) of the sixth to ninth cervical vertebrae were measured.A comparison of the differences between the directional asymmetries of the four vertebrae was found to be statistically significant, but there were no differences among strains. The left TP was usually longer than the right, the mean difference being 0.126mm. It appears that this asymmetry is directional rather than random.Variation in fluctuating asymmetry among strains was highly significant: the F1 hybrids were less asymmetric than their inbred parents. If we assume that the fluctuating asymmetry in length of the TP's of the cervical vertebrae is a result of developmental instability in the bird, it is reasonable to expect that heterozygosity might reduce this instability. This was found in this study.Directional and fluctuating asymmetries are positively correlated with each other (r=0.696). In other words, those vertebrae which showed high directional asymmetry had simultaneosly high fluctuating asymmetry. Correlation between body weight and TP length was estimated to be 0.789, whereas body weight was not significantly correlated with either directional or fluctuating asymmetry. It should be mentioned that neither directional nor fluctuating asymmetry is significantly correlated with TP length or with the difference between the lengths of the TP of the F1 hybrids and the corresponding mid-parental values.
Fluctuating asymmetry
Cite
Citations (3)