scholarly journals How and why patterns of sexual dimorphism in human faces vary across the world

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Karel Kleisner ◽  
Petr Tureček ◽  
S. Craig Roberts ◽  
Jan Havlíček ◽  
Jaroslava Varella Valentova ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Mate Choice ◽  
Body Height ◽  
Human Populations ◽  
Sexually Dimorphic ◽  
Shape Variation ◽  
Cross Cultural Differences ◽  
Facial Shape ◽  
Human Faces

AbstractSexual selection, including mate choice and intrasexual competition, is responsible for the evolution of some of the most elaborated and sexually dimorphic traits in animals. Although there is sexual dimorphism in the shape of human faces, it is not clear whether this is similarly due to mate choice, or whether mate choice affects only part of the facial shape difference between men and women. Here we explore these questions by investigating patterns of both facial shape and facial preference across a diverse set of human populations. We find evidence that human populations vary substantially and unexpectedly in both the magnitude and direction of facial sexually dimorphic traits. In particular, European and South American populations display larger levels of facial sexual dimorphism than African populations. Neither cross-cultural differences in facial shape variation, sex differences in body height, nor differing preferences for facial femininity and masculinity across countries, explain the observed patterns of facial dimorphism. Altogether, the association between sexual shape dimorphism and attractiveness is moderate for women and weak (or absent) for men. Analysis that distinguishes between allometric and non-allometric components reveals that non-allometric facial dimorphism is preferred in women’s faces but not in faces of men. This might be due to different regimes of ongoing sexual selection acting on men, such as stronger intersexual selection for body height and more intense intrasexual physical competition, compared with women.

scholarly journals How and why patterns of sexual dimorphism in human faces vary across the world

2020 ◽  
Author(s):  
Karel Kleisner ◽  
Petr Tureček ◽  
S. Craig Roberts ◽  
Jan Havlicek ◽  
Jaroslava Varella Valentova ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Mate Choice ◽  
Body Height ◽  
Human Populations ◽  
Sexually Dimorphic ◽  
Shape Variation ◽  
Cross Cultural Differences ◽  
Facial Shape ◽  
Human Faces

Sexual selection, including mate choice and intrasexual competition, is responsible for the evolution of some of the most elaborated and sexually dimorphic traits in animals. Although there is clear sexual dimorphism in the shape of human faces, it is not clear whether this is similarly due to mate choice, or whether mate choice affects only part of the facial shape difference between men and women. Here we explore these questions by investigating patterns of both facial shape and facial preference across a diverse set of human populations. We find evidence that human populations vary substantially and unexpectedly in both the range and pattern of facial sexually dimorphic traits. In particular, European and South American populations display larger levels of facial sexual dimorphism than African populations. Neither cross-cultural differences in facial shape variation, differences in body height between sexes, nor differing preferences for facial sex-typicality across countries, explain the observed patterns of facial dimorphism. Altogether, the association between morphological sex-typicality and attractiveness is moderate for women and weak (or absent) for men. Analysis that distinguishes between allometric and non-allometric components reveals that non-allometric sex-typicality is preferred in women’s faces but not in faces of men. This might be due to different regimes of ongoing sexual selection acting on men, such as stronger intersexual selection for body height and more intense intrasexual physical competition, compared with women.

scholarly journals Facial and body sexual dimorphism are not interconnected in the Maasai

2022 ◽  
Vol 41 (1) ◽  
Author(s):  
Marina L. Butovskaya ◽  
Victoria V. Rostovtseva ◽  
Anna A. Mezentseva
Keyword(s):  
Sexual Dimorphism ◽  
Body Height ◽  
The Body ◽  
Whole Body ◽  
Human Populations ◽  
Factors Affecting ◽  
Trade Offs ◽  
Facial Shape ◽  
The Face ◽  
Full Face

Abstract Background In this paper, we investigate facial sexual dimorphism and its’ association with body dimorphism in Maasai, the traditional seminomadic population of Tanzania. We discuss findings on other human populations and possible factors affecting the developmental processes in Maasai. Methods Full-face anthropological photographs were obtained from 305 Maasai (185 men, 120 women) aged 17–90 years. Facial shape was assessed combining geometric morphometrics and classical facial indices. Body parameters were measured directly using precise anthropological instruments. Results Sexual dimorphism in Maasai faces was low, sex explained 1.8% of the total shape variance. However, male faces were relatively narrower and vertically prolonged, with slightly wider noses, narrower-set and lower eyebrows, wider mouths, and higher forehead hairline. The most sexually dimorphic regions of the face were the lower jaw and the nose. Facial width-to-height ratio (fWHR), measured in six known variants, revealed no significant sexual dimorphism. The allometric effects on facial traits were mostly related to the face growth, rather than the growth of the whole body (body height). Significant body dimorphism was demonstrated, men being significantly higher, with larger wrist diameter and hand grip strength, and women having higher BMI, hips circumferences, upper arm circumferences, triceps skinfolds. Facial and body sexual dimorphisms were not associated. Conclusions Facial sex differences in Maasai are very low, while on the contrary, the body sexual dimorphism is high. There were practically no associations between facial and body measures. These findings are interpreted in the light of trade-offs between environmental, cultural, and sexual selection pressures.

scholarly journals Artificial sexual selection alters allometry in the stalk-eyed fly Cyrtodiopsis dalmanni (Diptera: Diopsidae)

1993 ◽  
Vol 62 (3) ◽  
pp. 213-222 ◽  
Author(s):  
Gerald S. Wilkinson
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Body Length ◽  
Sexually Dimorphic ◽  
Selected Lines ◽  
Variable Intensity ◽  
High Line ◽  
Cumulative Selection ◽  
Selection For ◽  
Selection Of

SummarySelection for increased and decreased ratio of eye span to body length was exerted on male stalk-eyed flies (Cyrtodiopsis dalmanni) from Malaysia using replicate selected and unselected lines. Response to selection was symmetrical. After 10 generations high line male eye span increased to 1·3 body lengths while low line male eye span declined to 1·1 body lengths. Realized heritabilities for eye span to body length ratio, estimated using regressions of deviations from unselected controls on cumulative selection differentials, were greater than zero for all four selected lines with average h2 = 0·35 + 0·06. The static linear allometric relationship between eye span and body length diverged between selected lines and rotated among selected line males in the same direction as among males in other sexually dimorphic diopsid species. Crosses between lines after 13 generations of selection indicate that the genes which influence relative eye span combine additively and do not exhibit sex linkage or maternal effects. The genetic correlation between the sexes, 0·29 + 0·05 as estimated by the regression of female on male change in eye span, did not prevent sexual dimorphism in eye span from diverging between lines. These results suggest that the exaggerated eye span of male C. dalmanni is maintained by natural selection opposing sexual selection rather than by lack of or asymmetry in additive genetic variation. Furthermore, the variation in sexual dimorphism for eye span-body length allometry observed among extant diopsid species is consistent with sexual selection of variable intensity acting on relative eye span.

scholarly journals A cross-cultural study of sex-typicality and averageness: Correlation between frontal and lateral measures of human faces

2017 ◽  
Author(s):  
Dariusz P. Danel ◽  
Jaroslava Varella Valentova ◽  
Oscar R. Sánchez ◽  
Juan D. Leongómez ◽  
Marco A. C. Varella ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Cultural Study ◽  
Cross Cultural ◽  
Sexually Dimorphic ◽  
Geometric Morphometric ◽  
Lateral Projection ◽  
Cross Cultural Study ◽  
Mutual Relations ◽  
Human Faces ◽  
Published Research

AbstractObjectivesFacial averageness and sexual dimorphism are extensively studied attractiveness markers, which are viewed as possible indicators of biological quality. Both are complex morphological traits and both can be easily assessed from frontal and lateral projection of a human face. Interestingly, examination of mutual relations between the frontal and lateral dimensions of these markers has so far received little attention in published research.MethodsIn our cross-cultural study, we used geometric morphometric data from male and female faces from Brazil, Cameroon, Colombia, and the Czech Republic, and analysed correlations between frontal and lateral measurements of averageness and degree of maleness/femaleness, i.e. individual variation in features that characterize sexual dimorphism. We also analysed whether the association between frontal and lateral measurements differs in men and women.ResultsIn general, our results showed a moderate correlation in sexually dimorphic features between lateral and frontal facial configuration in both sexes, while frontal and lateral facial averageness was moderately correlated only in women. This pattern was less consistent when individual populations were analysed separately.ConclusionsReferring to the multiple signalling theory, we propose that especially in women, lateral/frontal correlations support a hypothesis of redundancy of information provided by the frontal and lateral dimension of a given facial attractiveness marker. The absence of a significant correlation in male facial averageness suggests that frontal and lateral averageness may convey different information about an individual.

scholarly journals Sexual dimorphism of the mandibular conformational changes in aging human adults: A multislice computed tomographic study by geometric morphometrics

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253564
Author(s):  
Leonor Costa Mendes ◽  
Julien Delrieu ◽  
Claudia Gillet ◽  
Norbert Telmon ◽  
Delphine Maret ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Conformational Changes ◽  
Sexually Dimorphic ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Computed Tomographic ◽  
Age Related ◽  
Human Adults ◽  
Geometric Morphometric Analysis ◽  
Shape Changes

The aging process has an impact on mandibular bone morphology and can therefore affect shape sexual dimorphism. Understanding the effect of senescence on mandibular shape changes is particularly important to correctly estimate the sex of an individual and predict age-related conformational modifications. The purpose of this study was to assess age-related changes in mandibular shape and sexual dimorphism. The study sample comprised 160 Multi Slice Computed Tomography examinations of individuals aged 40 to 79 years. Geometric morphometric analysis of fourteen osteometric landmarks was used to examine sexual dimorphism and patterns of mandibular shape variation with age. Results showed that mandibular sexual dimorphism of shape remained significant with aging. Conformational changes occurred between 50 and 70 years and were different for male and female individuals. Females presented earlier and more marked age-related shape changes than males. These observations suggest that mandibular senescence is a sexually dimorphic process since its onset, rate, and the areas subjected to conformational changes differ from male to female individuals. Senescence-related changes present substantial variability, and further investigation is required to determine precisely the age that marks their onset.

Sexual dimorphism in two savannah sparrow populations

1980 ◽  
Vol 58 (3) ◽  
pp. 412-415 ◽  
Author(s):  
Patrick J. Weatherhead
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Stabilizing Selection ◽  
Sexually Dimorphic ◽  
Mainland Population ◽  
Savannah Sparrow ◽  
Savannah Sparrows ◽  
Insular Population

Contrary to predictions, a monogamous, mainland population of savannah sparrows was found to be more sexually dimorphic than a polygynous, insular population. When only trophic characters were considered, the insular population fit the prediction of greater sexual dimorphism. Several explanations for increased sexual selection or decreased stabilizing selection in the more dimorphic population are considered. While none of the explanations seem readily applicable from the available evidence, further avenues of investigation are suggested.

Nothobranchius furzeri as an emerging model for mate choice: female choice revealed by animations

Behaviour ◽  
2020 ◽  
Vol 158 (1) ◽  
pp. 35-49
Author(s):  
Bernadette D. Johnson ◽  
Avrie Fox ◽  
Landon R. Wright ◽  
Ginger E. Carney ◽  
Barrie D. Robison ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Female Choice ◽  
Genetic Basis ◽  
Sexually Dimorphic ◽  
Research Model ◽  
Computer Animations ◽  
Nothobranchius Furzeri ◽  
Black Band ◽  
Female Responses

Abstract The African turquoise killifish (Nothobranchius furzeri) is the shortest-lived vertebrate research model. It is also sexually dimorphic, making it suitable for studying sexual selection. We take advantage of a natural tail colour polymorphism in males and investigate female responses to computer animations of males that differ in this phenotype. Our findings indicate that GRZ (Gonarezhou) females prefer animated males with traits specific to their strain (a yellow tail with a black band) compared to males exhibiting traits from another strain of the same species (a red tail). When females were simultaneously shown animations of both males, they spent significantly more time on the side of the tank where the yellow-tailed animation was visible, and significantly more time interacting with the yellow-tailed animation. Given these repeatable responses and the availability of genomic resources, N. furzeri represents an excellent, untapped model for studying the genetic basis of preferences and reproductive behaviours.

Sexual dimorphism and sex pheromone detection in Aphidoletes aphidimyza

2020 ◽  
Vol 70 (1) ◽  
pp. 13-25
Author(s):  
Aurore Nicolas ◽  
Julie Pourtois ◽  
Pol Karier ◽  
István Markó ◽  
Thierry Hance
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Pheromone ◽  
Choice Experiments ◽  
Morphometric Study ◽  
Sexually Dimorphic ◽  
Aphidoletes Aphidimyza ◽  
Long Distance ◽  
The Right ◽  
The Relationship

Abstract Sexual dimorphism, particularly at the level of sensory and locomotor organs, is usually attributed to sexual selection. Antennae are notably developed in males of species that need to detect a sex pheromone at low concentration or at long distance. In addition to their role in intrasexual selection, antennae can be seen as important ornaments in intersexual selection. Antennae of Aphidoletes aphidimyza are clearly sexually dimorphic (males have longer antennae than females, with highly developed sensilla) while females emit a sex pheromone for mating. Males with longer and more symmetrical antennae than others could be more successful in reaching the source of sex pheromone, especially if they can fly properly. A morphometric study was first conducted, to apprehend the variability of antennae, wings and tibias in lab conditions. The length of the antennae of male A. aphidimyza is impressive and the right antenna is longer than the left antenna. Secondly, choice experiments were conducted in a Y-shaped olfactometer with males of A. aphidimyza facing the sex pheromone. The relationship between choice patterns and morphology of males was then studied, but no link was found between the morphology of males and their behaviour while exposed to the sex pheromone, although males were indeed attracted by the olfactometer arm containing the sex pheromone.

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

2012 ◽  
Vol 279 (1737) ◽  
pp. 2457-2463 ◽  
Author(s):  
Konstanze Meindl ◽  
Sonja Windhager ◽  
Bernard Wallner ◽  
Katrin Schaefer
Keyword(s):  
Adult Male ◽  
Body Height ◽  
Digit Ratio ◽  
Life History Strategies ◽  
Shape Variation ◽  
Lower Face ◽  
Digit Ratios ◽  
Fourth Digit ◽  
Facial Shape ◽  
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.

Differences in sexual dimorphism among four gazelle taxa (Gazella spp.) in the Middle East

2010 ◽  
Vol 60 (4) ◽  
pp. 395-412 ◽  
Author(s):  
Peter Cunningham ◽  
Martin Plath ◽  
Torsten Wronski ◽  
Mohamed Sandouka
Keyword(s):  
Body Weight ◽  
Sexual Selection ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Mating Systems ◽  
Research Centre ◽  
Sexually Dimorphic ◽  
Male Sex ◽  
The Difference ◽  
Horn Development

AbstractSexual selection can lead to sexual dimorphism, where elaborated traits used in mate attraction or weaponry are more expressed in the male sex. The degree of sexual dimorphism, however, is known to vary even among closely related taxa. Here we examined sexual dimorphism in horn length and three measures related to body size (body weight, shoulder height, and neck circumference) in four gazelle taxa, representing at least three species, i.e. Dorcas gazelle (G. dorcas), Sand gazelle (G. subgutturosa marica) and Mountain gazelle (G. gazella). The latter is represented by two distinctive phenotypes maintained and bred at the King Khalid Wildlife Research Centre in Saudi Arabia. We describe marked differences in sexual dimorphism among taxa. For example, the difference in sexually dimorphic horn development was driven primarily by females exhibiting pronounced differences in horn development. We discuss how divergent mating systems, and group sizes affect these differences among the examined taxa, with more competition in larger groups probably promoting the evolution of larger horns in females, thereby leading to less sexual dimorphism.

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