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The Relationships between Symmetry and Attractiveness and Mating Relevant Decisions and Behavior: A Review



Evolutionary theory based research shows that attractiveness is based on biological correlates that index appropriate estrogen and testosterone levels. Symmetry affects or plays a role in the perception of many of these correlates of attractiveness. Additionally, since attractiveness affects infidelity perception and reactions, sexual satisfaction, and personality perception, symmetry also affects these areas. This paper reviews the literature on symmetry showing how symmetry affects: the correlates of attractiveness, sexual satisfaction, personality, and infidelity perceptions and reactions.
Symmetry 2010, 2, 1081-1098; doi:10.3390/sym2021081
ISSN 2073-8994
The Relationships between Symmetry and Attractiveness and
Mating Relevant Decisions and Behavior: A Review
T. Joel Wade
Department of Psychology, Bucknell University, Lewisburg, PA, 17837, USA;
Received: 30 April 2010; in revised form: 8 May 2010 / Accepted: 24 May 2010 /
Published: 26 May 2010
Abstract: Evolutionary theory based research shows that attractiveness is based on
biological correlates that index appropriate estrogen and testosterone levels. Symmetry
affects or plays a role in the perception of many of these correlates of attractiveness.
Additionally, since attractiveness affects infidelity perception and reactions, sexual
satisfaction, and personality perception, symmetry also affects these areas. This paper
reviews the literature on symmetry showing how symmetry affects: the correlates of
attractiveness, sexual satisfaction, personality, and infidelity perceptions and reactions.
Keywords: symmetry; attractiveness; attraction; mating decisions
1. Introduction
The results from prior research indicate that evaluations of physical and sexual attractiveness can be
guided by the execution of evolutionary adaptations based on finding the “best” mate and producing
the “best” offspring [1–16]. Individuals focus on reproductively relevant characteristics of the male
and female body and face in order to determine if the individual being rated is attractive and most
reproductively fit (likely to be reproductively successful). Consequently, attractiveness can be based
on facial and bodily characteristics that index sexual maturity, gender identity, and phenotypic quality
on facial and bodily characteristics that index sexual maturity, gender identity, and phenotypic quality
[15–17]. Developmental stability also plays a role. Fluctuating asymmetry is an intrinsic property of an
individual’s genome that provides an honest signal of individual quality [18]. Thus, it also influences
an individual’s identification of the “best” mates. This paper points out the correlates of attractiveness
for men and women, and then reviews the literature on symmetry and attractiveness, and symmetry
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and mate relevant decisions and behavior to show how symmetry relates to or affects the correlates of
attractiveness and mate relevant decision making and behavior.
1.1. Sex Differences in Attractiveness Determinants
Since attractiveness has a biological basis, the characteristics of facial and bodily attractiveness
differ somewhat for men and women. Men’s attractiveness is based on facial and body characteristics
signaling dominance, status, masculinity, and good health [2–4,7–9,11,15–17,20]. Therefore, men with
high status and/or dominance and masculinity-related facial and body characteristics are considered
most physically and sexually attractive and the best choices to ensure reproductive success.
Testosterone and areas of the body indexing testosterone play key roles.
Dominant males have higher testosterone levels [21–23] and the size of men’s chests, biceps, their
muscular strength, and the size, shape, and tone of their physiques are characteristics influenced by
testosterone [24]. Thus, men with broad chests, muscular upper bodies, and smaller waists are
considered more dominant and more attractive [11,23,25,26]. Additionally, sexual activity is also
related to testosterone levels. Therefore, given that dominant males have more testosterone, research
shows that they copulate more frequently [20,27]. Similarly, dominant men are also said to have
stronger sex drives due to increased testosterone levels [23].
Chin breadth is also a testosterone-mediated characteristic [17,28]. Thus, dominant men have
broader chins and are considered more attractive [20,29]. This may be because pathogen resistance
[30–32] is indexed by human chin length. One other facial characteristic, nose size, is also affected by
testosterone. Nose size is a sexually dimorphic characteristic signaling gender identity [17]. Men
typically have larger noses than women because men have more testosterone. Thus, nose size can be
used to make inferences regarding whether or not one is male or female.
Stomach size and shape can also be a product of testosterone. Specifically, the size and shape of a
man’s stomach is the product of android fat deposits [10,11,24,33,34]. Thus, stomach size is also an
important characteristic, and men with smaller/less fat stomachs are considered more attractive and
healthier [24–26,33,34]. Additionally, good physical condition and muscular development are associated
with testosterone, dominance, and physical prowess [23] and these factors also play a role in
attractiveness assessments.
Women’s attractiveness and reproductive success are based on cues from facial and body
characteristics that signal fecundity, successful mothering potential (the ability to most successfully
raise offspring independent of the ability to become pregnant), femininity, and pathogen
resistance [2–7,9,10,12–17].
The most important and most visible physical cue for women is the waist-to-hip ratio (WHR)
[13,17]. The WHR is related to crucial endocrine states associated with fecundity and successful
mothering, and femininity is inferred from it [9,10,12]. This is due to gynoid fat being distributed on
the thighs, legs, buttocks, waist, and hips of women [9,12,23]. Women who appear to have small hips,
small waists, medium to small buttocks, and medium legs [35] are considered more attractive,
healthier, more feminine, most fertile, and better potential mothers [9–12,14,17]. Additionally,
women’s waist size is an indicator of their risk for disease, is used to assess their hormonal status, and
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is correlated with cardiovascular disorders, diabetes, and gall bladder problems [14,36]. But, is WHR
the best predictor of attractiveness?
Some researchers suggest that an attractiveness assessment based on WHR is a product of changes
in BMI such that BMI is a better predictor of female attractiveness than WHR [37,38]. However,
recent research, using photographs of pre and post surgical patients, comparing the contributions of
WHR and BMI to women’s attractiveness assessments, reports that women with lower WHR are rated
as more attractive regardless of changes in their BMI [39,40].
Cheekbone breadth and size are also evolutionary relevant characteristics. Women with high
cheekbones are considered more attractive, more feminine, healthier, and more fertile [2,4,17]. This is
due to women’s cheekbone size indexing pathogen resistance [30–32]. Women’s breasts and the
appearance of their stomachs also play a role [9,10,12–14,17]. This is because gynoid fat is distributed
on the abdomens of women [9,10,12,24], and women with large breasts are considered more attractive,
more feminine, healthier, and most desirable for long- and short-term relationships [14].
Lip size also plays a role because lip size is also an estrogen-mediated trait [41] and an indicator of
femininity and attractiveness [17]. The size of a woman’s eyes is also important. However, the eyes are
not estrogen-mediated characteristics. But, the eyes get smaller with age [15]. So, eye size becomes a
heuristic for youth and fertility. Not surprisingly, then, women with large round eyes are considered
more attractive, more fertile, and healthier [2,4,17]. Physical condition is important as well. This is
because good physical fitness is related to fecundity [42,43] and may also signal phenotypic quality [17].
In addition to the facial and bodily components delineated above, attractiveness is also a product of
pheromones [44], height [45,46], vocal quality [47–49] pupil size [50,51], hair length and quality [52,53],
leg length [54], and foot size [55]. These attractiveness foci are also the product of evolutionary
adaptations designed to help one select the best mate. But, what about developmental stability?
2. Discussion
2.1. Developmental Stability
Since attractiveness is based on biological adaptations predicated on producing the best offspring
one would assume that individuals would want to select partners who seem to be the products of a
stable development as this might best insure the production of the most healthy offspring. So,
developmental stability should play a role. Developmental stability refers to the capacity of an
individual to produce a well developed symmetrical phenotype in the face of developmental
perturbations caused by disease, toxins, parasites, etc. [56]. Since symmetry of the face and body
indexes developmental stability [57,58], research indicates that symmetry does play a role in mate
assessment. Prior research indicates that departures from symmetry reflect an individual’s incapacity to
maintain developmental homeostasis [29,59,60]. Thus, not surprisingly, since sexual selection favors
those traits that indicate the ability to withstand parasites [61], research shows that symmetry affects
the perception of many of the correlates of attractiveness delineated above. Preferences for a
symmetrical mate may have evolved because of positive genetic effects on offspring survival [57].
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2.2. Facial Symmetry and Facial Attractiveness
As mentioned above, many aspects of the face play a role in attractiveness judgements. Aesthetic
judgements of faces are not capricious, but reflect evolutionary functional assessments of potential
mates [57]. Research examining facial symmetry shows that overall symmetry of the face does
influence perceptions of the face. But, why would facial symmetry be important?
Since the face displays secondary sexual characteristics facial symmetry is more sensitive to
environmental perturbations [57]. Facial asymmetry is located in various sites in the face [62].
Consequently, facial symmetry functions like a certificate of health with regards to mate potential [63].
Women are seen as more attractive when their faces are symmetrical and close to average [63].
Asymmetric divergences away from average may indicate environmental perturbations during
development, genetic problems or psychological distress. In addition, facial symmetry predicts facial
attractiveness and facial attractiveness is a reliable indicator of developmental stability [64]. Thus,
facial attractiveness of both sexes signals genetic quality in the form of developmental stability [64].
Additionally, facial symmetry is correlated with attractiveness in both men and women [65]. Selecting
a genetically distinct/diverse mate can facilitate an offspring’s ability to resist parasites. Consistent
with that, preferences for symmetry may be a mate choice adaptation rather than a byproduct of
strategies used to process visual stimuli [65]. So, facial symmetry is important for attractiveness
evaluations for adaptive reasons. Consistent with this, facial symmetry displays underlying genetic
diversity and parasite resistance and consequently, a symmetrical face displays developmental
homeostasis [66]. Similarly, symmetrical faces are judged as healthier than asymmetrical faces and this
relationship remains even after the effect of attractiveness is partialed out [67], showing that humans
have an adaptive preference for faces that signal quality. In addition, the preference for facial
symmetry is not due to perceptual preference [68]. Rather, it is due to an evolutionary adaptation to
facilitate mate selection. Thus, there is cross cultural agreement on the attractiveness of symmetry [69].
Clearly, the preponderance of research indicates that facial symmetry is important for attractiveness
and mate selection decisions. But what about the body? Does symmetry of the body affect
2.3. Body Symmetry and Attractiveness
Research has examined the symmetry of individual parts of the body and overall symmetry of the
body. Body symmetry is a major correlate of attractiveness [70]. Similarly, attractiveness for women is
related to body symmetry [71]. More recently, researchers have reported that overall asymmetry is
related to attractiveness for both men and women [64]. For women, this is due to symmetry’s
relationship to reproductive potential. Overall asymmetry is related to reproductive potential in
women [72,73]. Higher symmetry leads to greater reproductive potential. In addition, for both men and
women this relationship between body symmetry and attractiveness most likely occurs due to
symmetry’s reflection of overall quality of development. Research with animals indicates that
symmetry reflects the overall quality of development [61,70,74,75]. Thus, similarly, overall body
symmetry in humans plays a role in attractiveness evaluations. But, is this true for specific parts of the
body that are evolutionarily significant with respect to attractiveness evaluation.
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2.4. Breast Symmetry
Recent directional selection has played a role in the evolution of adult female breast size [73].
Furthermore, the rapid development of breasts prior to and during puberty and their role in interactions
between men and women indicates that the breasts may play a role in sexual selection [73,76,77]. This
is not surprising because breasts are secondary sexual characteristics, and secondary sexual
characteristics play a role in determinations of whether or not an individual is sexually mature, male or
female, and can create and best care for children [15,16]. Also, breasts signal mate quality [78–80].
Since developmental stability also signals mate quality and developmental stability is indexed by
symmetry and the breasts signal mate quality, one might assume that the symmetry of women’s breasts
also plays a role in assessments of their mate quality. In fact, breasts are expected to demonstrate
higher levels of developmental instability than other body parts [81]. Also, breast symmetry is large
compared to other structural characteristics of the body [73]. Thus, breast symmetry should play a role
in mate choice related adaptations.
In line with the aforementioned assumption, experimental research, shows that breast asymmetry
does play a role in aspects of mate quality. Specifically, breast asymmetry plays a role in attractiveness
and health judgements [82]. Additionally, research that incorporates actual measurements of breast
symmetry in US and Spanish samples finds that breast asymmetry is negatively correlated with the
number of children women have [73]. Women with symmetrical breasts have more children. While
there may be additional reasons for this, one reason this may occur is because these women are rated as
more attractive and consequently are selected for mating more often. Choosy men who use breast
symmetry as a cue for mate selection will experience an advantage in terms of reproductive success
[73]. Also, since breast symmetry is heritable [73,78] these men gain a selection advantage because
their daughters should experience higher mating success and fecundity [73]. So, one can conclude that
breast symmetry is a reliable signal of reproductive potential [73]. Clearly, facial, overall body
symmetry, and breast symmetry play a role in attractiveness related judgements. But, does symmetry
affect other correlates of attractiveness? Since symmetry indexes developmental stability and
attractiveness it should also affect other body characteristics used to make attractiveness judgements.
2.5. Vocal Quality
Both correlational and experimental research shows that vocal quality influences attractiveness
assessments. Men with lower pitched voices are considered more attractive and more
masculine [47,49] and women with higher pitched voices are considered more attractive and more
feminine [48]. Additionally, female vocal quality is associated with facialmetric assessments of
femininity [84]. Also, men and women with attractive voices tend to have more sexually dimorphic
body configurations that reflect activational hormone exposure seen at puberty [85]. Men with
attractive voices had broader shoulders and women with attractive voices had hourglass figures [85].
This further indicates that vocal quality is associated with development and developmental stability.
Vocal pitch is one vocal quality associated with development that has been examined due to its
developmental significance. Vocal pitch changes as one reaches puberty due to the hormonal changes
that occur [48,86–88]. The size and thickness of the vocal folds determine the fundamental frequency
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(pitch) of the voice: thicker vocal folds give rise to a lower voice. [48,87]. Males’ vocal chords thicken
and increase in size and their voices become deeper [47,49] and women’s voices become higher at
puberty [48]. So, pitch can indicate the general hormonal state and age of a speaker [48]. Since the voice
changes with development, developmental stability is important for mate selection, and symmetry
indexes developmental stability, vocal quality should be related to developmental stability. Indeed,
individuals with voices rated as attractive have bilateral body traits that are more symmetrical [89].
As symmetry increases, ratings of vocal attractiveness increase [89]. So, vocal quality is associated with
symmetry. What about other attractiveness cues?
2.6. Pheromones
Olfactory cues produced by men play a major role in the human sexual selection system [90].
Women’s sexual attractiveness is more influenced by male scent than by visual features [91,92]. This is
because women are extremely sensitive to Androstenol and men produce more of this than women do
[93,94]. The male pheromone can signal immunocompetence [95]. So, pheromones can function as
indices of developmental stability. With that in mind, one would expect symmetry to be related to
pheromones since symmetry indexes developmental stability. Research has indeed found that symmetry
is related to pheromone production in men. In research where women were asked to smell the t-shirts of
men, women rated the t-shirts of symmetrical men as more attractive [96]. This effect is even stronger
when the effect of bathing by the men is controlled for [97]. This preference for the scent of symmetric
men is strongest when women are in the fertile phases of their menstrual cycles [90,98]. In addition to
affecting attractiveness decisions, symmetry also plays a role in behavior related to attractiveness.
2.7. Mate Protection
One type of parental investment that women desire from male partners is a parental investment that
affords them and their offspring protection [99]. Symmetrical men are perceived as better protectors of
their mates than asymmetric men [100]. This may be because symmetric men are healthier [62,101–103]
and consequently better equipped to fend off attacks. Additionally, since symmetry is associated with
cognitive ability [104–106] symmetrical men may be better able to outsmart attackers, thus affording
protection to their mates and offspring. Similarly, symmetrical men by virtue of their intelligence may
fare better in employment contexts which would afford them a better ability to buy protection for their
mates and offspring. Thus, the relationship between symmetry and mate protection. However, while
these men with low facial asymmetry (FA) have better genes such that they are better protectors and
more intelligent, they are not better fathers than high FA men since low FA men are more likely to
commit adultery [100] (more detail regarding infidelity is presented later in this paper).
2.8. Human Female Orgasm
Women can exert a choice adaptation designed to manipulate sperm competition, promote
conception with men of high quality, retain the sperm of high quality sires, and promote, create, and
maintain a pair bond with men [107,108]. That choice adaptation is the female orgasm. The orgasm is
not needed for conception [107,109]. But, it can enhance the likelihood of conception via the up-suck
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hypothesis where orgasmic contractions force the mouth of the uterus into the pool of sperm deposited
in the vagina upon ejaculation [109]. Evolutionarily, women benefit from having offspring with males
of high quality. So, male attractiveness plays a role in female orgasmic responses [108]. Since
attractiveness plays a role in orgasmic responses and symmetry is related to attractiveness, symmetry
should also play a role in human female orgasm. A study with 86 heterosexual adult couples, found
that women with men who possessed low fluctuating asymmetry of the body self-reported and were
reported by their partners to have had more orgasms during copulation than women with men
possessing higher fluctuating asymmetry [108]. Additionally, women with men of low fluctuating
asymmetry of the body did not simply have more orgasms in general than other women [108]. Rather,
these women are only more orgasmic during copulation. Also, women’s self-reports of their orgasmic
behavior and their partner’s reports of their orgasmic behavior correlated near .60 and the correlation
between averaged reports and the true rate of orgasm was 0.85 [108]. So, these findings can be
considered very valid. Symmetrical men may also provoke more orgasms because symmetrical men
have higher quality sperm.
2.9. Sperm Quality
Women find men with good genes appealing [110] and symmetry indexes good genes. Sperm
quality is also an index of good genes. So, symmetry is also associated with sperm quality. In a study
of 53 men from a fertility clinic, men with higher symmetry in digits 2 to 5 were found to produce
more sperm per ejaculate, have faster sperm, and have sperm that are better migrators [111].
Additionally, men with greater overall symmetry produce more sperm per ejaculate and have faster
sperm [111]. Similarly, in a study including 34 men not being treated for infertility, men with greater
symmetry of the second digit, ears, wrists, and ankles were found to have more sperm per ejaculate
than men with lower symmetry [112].
2.10. Sexual Behavior
Attractive individuals have better sex lives [113] and they are preferred as sexual partners [19]. Since
attractiveness and sexual behavior are associated, symmetry should also be associated with sexual
behavior. Indeed, in a study with 122 participants, overall symmetry was found to predict the lifetime
number of sexual partners, i.e., men with symmetric body measures attract more sexual partners [114].
Additionally, this effect remains after attractiveness is partialed out [114]. This effect is most likely
due to a choice adaptation by women designed to control the quality of their offspring since symmetry
is heritable [56,115]. Symmetry also affects age of first intercourse for men. Men with higher
symmetry report having their first intercourse at an earlier age than men with less symmetry [114].
2.11. Infidelity
Both married men and married women engage in sex with individuals other than their partners, i.e.,
extrapair copulations (EPCs). Estimates place the rate of cheating among women at 15% to 70% with a
median of 30% [100,116–118] and at 25% to 50% for married men [118–120]. One of the reasons men
engage in EPCs is because EPCs may increase their quantity of offspring. According to sexual
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strategies theory [19] men prefer short term mating because it allows them to increase their probability
of having offspring with many women and consequently getting their genes into the future population.
Long term mating with one woman can lead to significant mating costs with no guaranteed payoff of
offspring. So, men prefer short term mating. EPCs are short term matings where effort put toward the
mating is small [100]. So, short term mating does not have the same costs for men that long term
mating has. One of the reasons women engage in EPCs is because EPCs may increase the quality of
their offspring. Potentially, women may be able to achieve genetic benefits as well as investment by
engaging in EPCs [107,121].
Individuals want mates who can resist pathogens and parasites [62]. One marker of pathogen
resistance is symmetry. Developmental quality, high symmetry, is associated with high mating
success [114]. So, EPC partners should exhibit developmental stability if individuals want mates that
are more pathogen resistant. In a study with 203 heterosexual couples, high symmetry was found to
predict men’s number of EPC partners, and men with high symmetry were selected as EPC partners
more often than men with low symmetry [100]. Additionally, this is independent of men’s number of
sex partners other than EPC partners, and the effect exists when age, sex, SES, salary, attractiveness,
and attachment style are controlled for [100]. Also, men with high symmetry are more likely to pursue
EPCs than men with low symmetry [100]. These men may be more motivated to pursue a short term
mating strategy.
2.12. Athletic and Talent Displays
One of the ways men and women attract mates is through intersexual and intrasexual
competition [122,123]. This competition takes place via display behavior where both sexes try to
display the attributes that the opposite sex prefers. Since men place an emphasis on women with high
reproductive fitness, femininity, and successful mothering potential [15,16,99] women display these
attributes. They dress in ways that emphasize the body parts that index these attributes [124–126]. Since
women desire men who are dominant, and socially ascendant [15,16,99] men display these attributes.
They dress and behave in ways that indicate that they are dominant, financially successful, or
industrious [122,123].
Dominance and industriousness are products of testosterone [20–22] and testosterone influences
developmental stability [110]. One way men can display their dominance is via athletic ability.
So, there should be a relationship between athletic ability and symmetry. A study including 50 men,
controlling for age and experience, found that there is a relationship between athletic ability and
symmetry, i.e., faster middle distance runners have more symmetric ears and nostrils than slower
runners [127].
The ratio of the index and ringer fingers, 2D:4D, also plays a role. This ratio is an index of prenatal
testosterone [128,129] and a smaller ratio indicates a higher level of prenatal testosterone. The ratio is
fixed in-utero by the end of the 14th week (130–132). The 2D:4D ratio is assessed by measuring the
index and ringer fingers from tip of the finger to the proximal crease where the finger meets the palm,
and then diving the index finger length by the ringer finger length [133–135]. Since testosterone
influences developmental stability [110], not surprisingly, 2D:4D is also linked to developmental
stability and athletic and musical ability.
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A study with 304 soccer players, found that first team athletes have lower 2D:4D than reserves and
professional athletes have lower 2D:4D than controls [133]. Similarly, studies with 468 total
participants, report that individuals with lower 2D:4D have better physical fitness [136]. Additionally,
a study of 70 musicians and 164 controls, found that lower 2D:4D is associated with musical ability
such that men with lower 2D:4D occupy higher positions in their instrument sections [137]. So, since
2D:4D indexes athletic ability, musical ability, and developmental stability, not surprisingly then, it is
also related to attractiveness. Men with lower 2D:4D are rated higher in attractiveness than men with
higher 2D:4D [138,139]. Women with higher 2D:4D are also rated as more attractive than women with
lower 2D:4D [140]. Since 2D:4D indexes developmental stability and attractiveness it should be
related to symmetry. A study including 69 men, found that 2D:4D is negatively correlated with facial
asymmetry [141]. Individuals with lower 2D:4D had more symmetrical faces.
As mentioned above, one of the ways men and women attract mates is through intersexual and
intrasexual competition and display behavior where both sexes try to display the attributes that the
opposite sex prefers [122,123]. In addition to displays of musical and athletic ability, another way that
humans can display their fitness is via dancing. Dance may be a sexually selected courtship signal [142].
Also, symmetry is associated with locomotory traits or their functional effectiveness in humans [143].
Dancing involves locomotion. So, dancing should be a way to reveal genetic or phenotypic
quality, i.e., developmental stability, to potential partners. It should be related to symmetry since
symmetry indexes developmental stability and is associated with locomotory traits. A study with 183
dancers using motion capture technology, found that symmetrical men were perceived as better dancers
than asymmetrical men [143]. Similarly, symmetrical women were perceived as better dancers than
asymmetrical women. But, female symmetry accounted for 23% of the variance in dancing ability while
male symmetry accounted for 48% of male dancing ability [143]. Also, women had a stronger preference
for symmetrical male dancers while men preferred symmetrical and asymmetrical female dancers
equally. Additional research [144] also finds that men described as dancers are rated as more attractive
while descriptions of a woman as a dancer or not have no effect on attractiveness ratings of a woman. So,
dancing is also a way to reveal developmental stability.
2.13. Personality
Personality plays a role in mate selection. The most important Big-5 personality characteristics for
mate selection are Agreeableness and Openness [145]. Often decisions about the personality of others
are made without knowing anything about the individual other than what they look like, i.e., by
looking at their face [146,147]. Additionally, 75% of students tested believe the face is a valid guide to
character [146]. The personality decisions based on the face show a high level of consensus among
judges, with greater than chance accuracy also [148]. Configural properties of the face are used to
make these personality decisions. Symmetry is a configural property of the face. So, symmetry plays a
role in personality assessments also. A study with 146 men and 146 women, found a significant
positive association between extraversion and symmetry of the face using a landmark measure of the
face that includes peripheral regions of the face for both men and women [149]. Men and women with
more symmetrical faces are more extraverted. Also, in a study examining a set of faces which all had
valid personality measures available, Extraversion was found to be positively related to facial
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symmetry and Openness and Agreeableness were negatively related to facial symmetry [150].
Additionally, a study that included faces with unknown personality profiles and guesses about the
personalities of the individuals found that facial symmetry is negatively related to Neuroticism,
Agreeableness, and Conscientiousness [151]. Clearly, facial symmetry is a correlate of personality.
2.14. Emotional and Psychological Health
Evolutionary theory based research shows that individuals want mates who are healthy.
Consequently, facial and bodily characteristics that index health and fitness are used to determine
whether or not an individual is attractive [15,16,99]. As mentioned previously, since developmental
stability can indicate fitness, it is given considerable attention. Thus, symmetry is also related to
psychological and emotional health. Psychopathic individuals have greater symmetry than non-
psychopathic individuals [152,153]. This finding may occur because symmetry is related to
masculinity [110] and masculinity is a product of testosterone. Too much testosterone can lead to a
perception of over masculinization which is perceived as threatening and unfriendly and is associated
with behavioral problems like excessive aggression [154,155]. Also, symmetry is associated with
higher scores on self-report measures of psychological and emotional distress [101]. Developmentally
stable, i.e., symmetrical, individuals have better psychological and emotional health.
3. Conclusions
Symmetry is associated with many of the correlates of attractiveness. It also affects mate attraction
and mate retention related behaviors. Thus, one can conclude that developmental stability plays a
major role in attraction and mate retention related behaviors. However, symmetry has not been
investigated in relation to all of the correlates of attractiveness. Leg length, hair length and quality, and
pupil size have not been investigated in relation to symmetry. Since these are correlates of
attractiveness and play a role in mate selection, symmetry may be associated with the perception of
these attributes also. Thus, additional research is warranted.
While symmetry plays a role in mate selection and affects many attractiveness related behaviors,
the mechanism by which symmetry is detected or comes to influence behavior is not fully clear. A
good deal of research shows that women are responding differently to low FA and high FA men. With
this in mind two possible explanations regarding the mechanism can be put forth. (1) It is possible that
women are assessing the asymmetries directly via some subconscious means of measurement of body
parts and facial components. (2) Alternatively, women may be responding to a chemical signal from
men such as a pheromone, since research shows that symmetrical men smell better [97], without being
consciously aware of this. Of these two explanations the latter has more credibility since prior research
shows that symmetry is a correlate of attractiveness, but it is not a cue, i.e., it covaries with cues that
women use to determine men’s facial attractiveness [110]. Furthermore, the women in the
aforementioned research could not rate men’s facial symmetry accurately. In this research [110], the
relationship between symmetry and attractiveness remained even when symmetry cues were missing,
i.e., only the right or left half of faces were presented. Additional evidence supporting the
subconscious chemical mechanism for symmetry detection/assessment can also be found in the
research showing that: women are best at detecting facial symmetry during the menses phase of their
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cycle, and showing that this heightened ability to detect facial symmetry is not due to greater visual
sensitivity during this time [156], and in research showing that ovulating women prefer the scent of
symmetrical men [97,98]. Overall, the aforementioned research further supports the notion that
symmetry is a good genes marker.
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... In contrast to perceptual bias views, in which preferences for symmetry are an epiphenomenon of processing, the evolutionary advantage view suggests an evolutionary adaptation to identify high-quality mates may generate symmetry preferences, e.g., [21,31,32]. Symmetry has been linked to heritable fitness and may offer others a visual cue of how well that organism can develop a symmetric body plan under genetic and environmental stress. ...
... The results from adults partially support predictions of an evolutionary advantage view because preferences were higher for human faces than monkey, and marginally higher for human female faces than male faces. This is consistent with ideas that symmetry may be used as a guide to mate quality, e.g., [21,31,32] or general partnerships (including male-male friendship). Higher preferences for symmetry in adults, for who these partnerships are more relevant, than for children is also consistent with the evolutionary view. ...
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Background: Visual symmetry is often found attractive. Symmetry may be preferred either due to a bias in the visual system or due to evolutionary selection pressures related to partner preference. Simple perceptual bias views predict that symmetry preferences should be similar across types of stimuli and unlikely to be related to factors such as age. Methods: The current study examined preferences for symmetry across age groups (pre-puberty vs post-puberty) and stimuli type (human face vs monkey face). Pairs of images manipulated for symmetry were presented and participants asked to choose the image they preferred. Participants repeated the task and were asked to detect symmetry. Results: Both age of observer and stimuli type were associated with symmetry preferences. Older observers had higher preferences for symmetry but preferred it most in human vs monkey stimuli. Across both age groups, symmetry preferences and detection abilities were weakly related. Conclusions: The study supports some ideas from an evolutionary advantage view of symmetry preference, whereby symmetry is expected be higher for potential partners (here human faces) and higher post-puberty when partner choice becomes more relevant. Such potentially motivational based preferences challenge perceptual bias explanations as a sole explanation for symmetry preferences but may occur alongside them.
... This may influence the human ability to recognise symmetry. The strong bilateral symmetry of the human face can correlate to the attractiveness of potential partners [84]. However, this same correlation can still be shown without any symmetry cues of the face being visible by covering half of the face [72]. ...
Symmetry is often treated as a binary property. In contrast, this study demonstrates that symmetry (specifically reflection), as perceived by human vision, can be represented as a measure that is continuous in value which this work terms the ‘Degree of Symmetry’ (DoS). It is suggested that human perception can determine one axis to have a greater, lesser, or the same DoS compared to another axis. If human vision has evolved to pre-process image features to optimise visual cognition, then computational algorithms could benefit from aiming to replicate human performance. Using pairwise comparisons of symmetry axes and crowd-sourcing, datasets of symmetry axes can be ranked to give a relative DoS for each axis. Two new datasets are ranked using human perception and the analysis compared with mathematical models for symmetry and existing symmetry operators. Comparison is made by a new performance measure correlating rank-ordered lists and is termed as the ‘Symmetry Similarity’: estimating how similar to human vision an operator performs. These comparisons led to two main conclusions. Firstly that shape is more important than intensity to human perception. Secondly, that existing operators tested are not good predictors of human perception: the highest Symmetry Similarity of tested existing operators is only 17.6%. Two new DoS operators are demonstrated based on these findings. Using scale and rotation invariant features around an axis, a Deep Belief Network (DBN) is trained to make the same pairwise comparisons as human perception. It achieves a Symmetry Similarity of 52.3%, suggesting that it is a better predictor of human perception than previously tested algorithms. Analysis of this operator prompted the dataset to be extended. Two key conclusions from the analysis of the extended dataset are that the DoS for sections of axes can be linearly combined to form the DoS of the combined axis, and that the decrease in DoS when an axis is parallel offset from the optimal axis can be approximated to a Gaussian. The DBN based operator achieved a lower Symmetry Similarity of 44.1% against the extended dataset.
... Along a different vein, it may be informative to examine whether the presence or absence of cranial hair is related to assessments stemming from perceived symmetry. Alopecia may lead to a decrease in the visual level of face or head symmetry, and symmetry of appearance is one of the criteria of attractiveness, closely related to the physical quality of the organism (i.e., the decrease in symmetry may result from hormonal disorders, medical history, having parasites, or risky behaviour; see Etcoff, 2011;Thornhill & Moeller, 1997, Wade, 2010. Therefore, future experimental designs could include symmetry as a variable in order to tease apart the role it has on assessments as compared to cranial hair. ...
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The question of whether or not cranial hair affects perceptions of attractiveness, personality, career success, and other traits related to fitness for men in two populations was investigated in two experiments. Experiment 1 used a 2 (race) × 2 (cranial hair of man) design, and examined attractiveness, fitness, and socially desirable personality measures. Experiment 2 used a 2 (race) × 2 (cranial hair) design to determine perceived attractiveness, fitness-related traits, and the Big-5 dimensions of personality. Amount of cranial hair did not affect personality ratings on the dimensions of the Big-5 but did affect perceived socially desired aspects of personality (such as warmth, sophistication, kindness, etc.). In Experiment 1, the White man with hair received higher perceived attractiveness, personality, and fitness ratings than the bald White man, while no differences occurred for the Black men. For Experiment 2, when differences for amount of cranial hair occurred, the White man with hair and the Black man without hair received higher perceived fitness and career success ratings. These results are discussed in terms of prior research on male cranial hair.
... Facial symmetry is considered a measure of developmental stability (also prenatal) and may indicate the so-called hereditary genetic quality, which in biological sciences, is broadly understood as the organism's chances of passing on its genes to the next generations [5]. The striking external symmetry of the skull, in contrast to its asymmetrical inner pneumatised spaces, is another proof of the importance of symmetry as a physiological health indicator for behavioural mating choices [7]. Nevertheless, it should be emphasised that the symmetry problem of the head's structures plays an essential role in disciplines such as anthropology and clinical anatomy and by proxy also an important role in clinical disciplines, such as neurosurgery, craniofacial surgery, and reconstructive surgery. ...
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The study of symmetrical and non-symmetrical effects in physics, mathematics, mechanics, medicine, and numerical methods is a current topic due to the complexity of the experiments, calculations, and virtual simulations. However, there is a limited number of research publications in computational biomechanics focusing on the symmetry of numerical head models. The majority of the models in the researched literature are symmetrical. Thus, we stated a hypothesis wherever the symmetrical models might be more applicable in numerical analysis. We carried out in-depth studies about head symmetry through clinical data, medical images, materials models, and computer analysis. We concluded that the mapping of the entire geometry of the skull and brain is essential due to the significant differences that affect the results of numerical analyses and the possibility of misinterpretation of the tissue deformation under mechanical load results.
... When investigating the interaction between sex and shape properties, our findings also indicate a male advantage in detecting geometrical targets characterized by symmetry and closure. As far as symmetry is concerned, studies highlighted that both sexes show a preference for symmetrical faces and bodies (Wade, 2010) and that males prefer Since the earlier formulation of FDI, Witkin referred to the educational context as one of the most promising fields for applying his theoretical work (Witkin, 1976 The current study presents some limitations that could be addressed in future works. In summary, our findings highlight that target asymmetry and good continuation with the embedding context increase task difficulty in a spatial visualization test. ...
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Humans typically perceive visual patterns in a global manner, and are remarkably capable of extracting object shapes based on properties such as proximity, closure, symmetry, and good continuation. Notwithstanding people’s attitude toward perceptual grouping, the research highlighted differences in disembedding performance across individuals, summarized by the field dependence/independence dimension. Previous studies revealed that age and educational attainment explain part of this variability, whereas the role of sex is still highly debated. Also, which stimulus features primarily influence inter-individual variations in perceptual grouping has to be fully determined.Building upon these premises, we assessed the role of age, level of education and sex on performance at the Leuven-Embedded Figure Test - a proxy of disembedding abilities - in a sample of 391 cisgender individuals. We also investigated whether stimulus symmetry, closure, complexity, and continuation relate to task accuracy as a function of personal characteristics.Overall, target asymmetry and continuation with the embedding context increase task difficulty, whereas target complexity demonstrates a U-shaped relationship with disembedding performance. Further, results unveil sex differences that have not been reported so far in adults and support the association between age, educational attainment, and disembedding abilities. Male individuals also benefit more from target symmetry and closure and are better at recognizing shapes when the embedding context is challenging. Lastly, highly educated adults better recognize asymmetrical and open targets, as well as shapes embedded in complex contexts. Taken together, our findings show how shape features relate to individual characteristics in explaining field independence.
... Taking 1999;Muller et al., 2012). Lastly, all tested biomarkers were previously shown to be correlated with reproductive characteristics and reproductive success (Klimek, Galbarczyk, Nenko, & Jasienska, 2016;Loesch & Wolanski, 1985;Wade, 2010). ...
Objectives Fetal environmental conditions are crucial for life‐long health. Direct measurements of developmental conditions are limited in humans; thus, several biomarkers of those conditions have been proposed: that is, finger ridge‐counts, level of facial fluctuating asymmetry (FA), and digit ratio (2D:4D). Since all of these biomarkers share a similar gestational time of formation, we hypothesize that their values are significantly correlated. Materials and methods Data were collected at the Mogielica Human Ecology Study Site in southern Poland among 234 women. Finger ridge‐counts, level of facial FA, and 2D:4D have been measured. The two‐step analyses included Pearson's correlations of simple values of the biomarkers and correlations of composite variables calculated based on principal component analysis. Results We did not find any statistically significant correlations between finger ridge‐counts, FA, and 2D:4D in women. Similarly, we did not observe any correlations between three composites created from the biomarkers. Discussion Our results indicate that there are no relationships between the biomarkers, suggested as proxies of the quality of prenatal conditions, in a single population. This is the first study analyzing three different markers simultaneously. The lack of correlations may indicate that the tested biomarkers reflect, in fact, different environmental conditions, occurring in separate “critical windows” of development, or that the biomarkers are not valid as proxies of developmental conditions.
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ABSTRACT FOR WEB VERSION OF BOOK This monograph is on the evolutionary importance of music for hominin communication and in particular the emergence of a sing-song gestural proto language(or clusters of such languages) in early hunter-gatherer forms of the Homo genus from around one million years ago. The more complex messages of this primordial language consisted of holistic combinations or strings of utterances, melodic pitches and gestures that had to be learnt and expressed in their entirety, although a slight degree of lexical juggling of the components of these combinatory phrases was possible. Inspite of not being a fully open grammatical, this proto language that some refer to a ‘musilanguage’ was, nevertheless, capable of transmitting simple symbolic information. For this hypothetical language the monogram draws on primate studies, the fossil record, adult-infant communication, genetics, cognitive studies, linguistics, musicology: and the fact that the very first although slight archaeological evidence symbolic behaviour appears in the Homo genus from around 600,000 years ago As such, the Homo-made musilanguage represents a halfway house between instinctive primate communication and grammatical language that appeared in modern humans around 200,000 years ago. A short synopsis of the ideas presented in this book is also found in my chapter entitled ‘Nine Reasons that Support Prehistoric Hominin Musicality and Musilanguage’ in the 2020 book ‘Music in Human Experience: Perspectives on a Musical Species’ edited by Johnathan Friedmann, Cambridge Scholars Publishing, UK. [ISBN (10): 1-5275-8010-5 & (13): 978-1-5275-8010-7]
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Humans naturally perceive visual patterns in a global manner and are remarkably capable of extracting object shapes based on properties such as proximity, closure, symmetry, and good continuation. Notwithstanding the role of these properties in perceptual grouping, studies highlighted differences in disembedding performance across individuals, which are summarized by the field dependence dimension. Evidence suggests that age and educational attainment explain part of this variability, whereas the role of sex is still highly debated. Also, which stimulus features primarily influence inter-individual variations in perceptual grouping has still to be fully determined. Building upon these premises, we assessed the role of age, education level, and sex on performance at the Leuven Embedded Figure Test—a proxy of disembedding abilities—in 391 cisgender individuals. We also investigated to what extent shape symmetry, closure, complexity, and continuation relate to task accuracy. Overall, target asymmetry, closure, and good continuation with the embedding context increase task difficulty. Simpler shapes are more difficult to detect than those with more lines, yet context complexity impairs the recognition of complex targets (i.e., those with 6 lines or more) to a greater extent. Concerning demographic data, we confirm that age and educational attainment are significantly associated with disembedding abilities and reveal a perceptual advantage in males. In summary, our study further highlights the role of shape properties in disembedding performance and unveils sex differences not reported so far.
Nonverbal communication plays an instrumental role in the process of meeting someone in a potential romantic encounter, starting from determining if they are attractive, if they are interested in a relationship with us, and whether we would be compatible. In this chapter we highlight not just the nonverbal signs and signals of attraction, but attempt to articulate a deeper evolutionary derived meaning and reason for them. We examine the static features of faces and bodies that we find attractive, their relationship to health, fertility, and dominance (reproductive fitness), and then move to the dynamic nonverbal actions suggesting romantic interest, such as arousal and engagement, and finish by articulating those nonverbal markers that indicate attention, trust, and commitment. We hope this exploration of the static and dynamic characteristics of people will better illustrate how evolution can explain why and when people are attracted to each other.
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The examination of static and dynamic occlusal relationship are important in orthodontic diagnosis. Thus, this study aims to analysis the difference of occlusal cant and favored chewing side. This is cross-sectional study of 70 healthy dental students Universitas Sumatera Utara with complete dentition and have no orthodontics treatment history. The position of tongue spatula across on occlusal of both first bicuspids to assess the existence and degree of the canting occlusal based on extra-oral photograph. The occlusal cant positive if it coincided to inter pupil as transversal references and sectioned with facial midline as a vertical reference more than 3º. A modified direct method- visual observation was done to assess the favored chewing side. A chi-square test with p level 0.05 in evaluation of the null hypothesis that states there was a difference of occlusal cant and favored chewing side in those subjects. From 36 subjects with cant occlusal positive, there were 26 subjects with and 10 subjects without favored chewing side. Then, from 34 subjects with cant occlusal negative, there were 14 subjects with and 20 subjects without favored chewing side. There was a significant difference (p=0.017) between occlusal cant and favored chewing side. Subjects with complete teeth showed that favored chewing side tendency of 3,714 more often had an occlusal cant positive compared to favored chewing side negative. In conclusion, the significant difference of occlusal cant and favored chewing side in subjects with complete dentition can be considered as a preliminary study in order to understand the complexity of development of mandibular asymmetry.
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Physische Attraktivität ist in den letzten beiden Jahrzehnten zu einem intensiv untersuchten Gegenstand psychologischer Forschung geworden. Das vorliegende Buch macht wichtige empirische Befunde und zugrundeliegende theoretische Ansätze der Attraktivitätsforschung zum ersten Mal einem breiten deutschen Publikum zugänglich. (Klappentext) Attraktivität - Schönheit - Gesichterbeurteilung - Personenbeurteilung
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The consistency of physical attractiveness ratings across cultural groups was examined. In Study 1, recently arrived native Asian and Hispanic students and White Americans rated the attractiveness of Asian, Hispanic, Black, and White photographed women. The mean correlation between groups in attractiveness ratings was r = .93. Asians, Hispanics, and Whites were equally influenced by many facial features, but Asians were less influenced by some sexual maturity and expressive features. In Study 2, Taiwanese attractiveness ratings correlated with prior Asian, Hispanic, and American ratings, mean r = .91. Supporting Study 1, the Taiwanese also were less positively influenced by certain sexual maturity and expressive features. Exposure to Western media did not influence attractiveness ratings in either study. In Study 3, Black and White American men rated the attractiveness of Black female facial photos and body types. Mean facial attractiveness ratings were highly correlated ( r = .94), but as predicted Blacks and Whites varied in judging bodies. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Evidence is presented showing that body fat distribution as measured by waist-to-hip ratio (WHR) is correlated with youthfulness, reproductive endocrinologic status, and long-term health risk in women. Three studies show that men judge women with low WHR as attractive. Study 1 documents that minor changes in WHRs of Miss America winners and Playboy playmates have occurred over the past 30-60 years. Study 2 shows that college-age men find female figures with low WHR more attractive, healthier, and of greater reproductive value than figures with a higher WHR. In Study 3, 25- to 85-year-old men were found to prefer female figures with lower WHR and assign them higher ratings of attractiveness and reproductive potential. It is suggested that WHR represents an important bodily feature associated with physical attractiveness as well as with health and reproductive potential. A hypothesis is proposed to explain how WHR influences female attractiveness and its role in mate selection.
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The finding that women are attracted to men older than themselves whereas men are attracted to relatively younger women has been explained by social psychologists in terms of economic exchange rooted in traditional sex-role norms. An alternative evolutionary model suggests that males and females follow different reproductive strategies, and predicts a more complex relationship between gender and age preferences. In particular, males' preference for relatively Younger females should be minimal during early mating years, but should become more pronounced as the male gets older. Young females are expected to prefer somewhat older males during their early years and to change less as they age. We briefly review relevant theory and present results of six studies testing this prediction. Study 1 finds support for this gender-differentiated prediction in age preferences expressed in personal advertisements. Study 2 supports the prediction with marriage statistics from two U.S. cities. Study 3 examines the cross-generational robustness of the phenomenon, and finds the same pattern in marriage statistics from 1923. Study 4 replicates Study 1 using matrimonial advertisements from two European countries, and from India. Study 5 finds a consistent pattern in marriages recorded from 1913 through 1939 on a small island in the Philippines. Study 6 reveals the same pattern in singles advertisements placed by financially successful American women and men. We consider the limitations of previous normative and evolutionary explanations of age preferences and discuss the advantages of expanding previous models to include the life history perspective.
We examine the relationship of testosterone to tendencies to marry and divorce, and to the quality of marriage, of a large representative sample of men. The analysis shows that men producing more testosterone are less likely to marry and more likely to divorce. Once married they are more likely to leave home because of troubled marital relations, extramarital sex, hitting or throwing things at their spouses, and experiencing a lower quality of marital interaction. Sociological models that might be informed by this finding are examined, and its implications for subsequent research are discussed.