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Breast size varies substantially among women and influences perception of the woman by other people with regard to her attractiveness and other characteristics that are important in social contexts, including mating. The theory of sexual selection predicts that physical criteria of partner selection should be markers of the candidate’s desirable properties, mainly biological quality. Few studies, however, have examined whether breast size really signals biological quality or its components and whether observers accurately interpret these signals. Our first study encompassed 163 young women and aimed to establish actual correlates of breast size. The aim of the second study was to determine preferences and stereotypes related to breast size: 252–265 women and men evaluated female digital figures varying in, among other characteristics, breast size. Breast size (breast circumference minus chest circumference) was negatively associated with body asymmetry and positively associated with infections of the respiratory system, but did not correlate with infections of the digestive system, openness to casual sex, and testosterone and estradiol level. Women and men perceived breasts in a similar way to each other: the bigger the breasts the higher the reproductive efficiency, lactational efficiency, sexual desire, and promiscuity attributed to the woman. Nevertheless, large breasts were not regarded more attractive than average ones, though small breasts were the least attractive. In addition, big-breasted women were perceived as less faithful and less intelligent than women with average or small breasts. We discuss our results from the perspectives of evolutionary psychology, perceptual biases, and social stereotypes. Electronic supplementary material The online version of this article (10.1007/s10508-019-1464-z) contains supplementary material, which is available to authorized users.

Objectives Male preferences are believed to have played a role in the evolution of permanently enlarged breasts in human females. Although breast size and shape are proven to affect women's attractiveness, their relative importance has not been investigated thus far. We aime to address this gap. Methods We prepared two sets of stimuli, each comprising 49 high-quality color images of a topless woman in a three-quarter view that varied in breast size (from 1 to 7) and firmness (from 1 to 7). Set A depicted the glandular ptosis (ie, breast shape being manipulated but the nipple always directed forward), while Set B depicted true ptosis (both breast shape and nipple position being manipulated). Participants (aged 18-45) were assigned to Set A (62 women, 60 men) or Set B (76 women, 52 men). First, each participant indicated the most attractive woman in the set of images. Next, the participant chose the more attractive woman from pairs in which one female deviated from the participant's ideal in breast size and the other in breast firmness. Results Both men and women preferred breasts of average or slightly above-average size and high or extreme firmness. Glandular ptosis was as important for attractiveness as breast size, but true ptosis was of much greater importance. Men preferred slightly bigger breasts than women. Conclusions Further attempts to explain evolution of permanent breasts in human females should give greater attention to breast shape than has previously been the case.

Studies of the protective effect of breastfeeding on asthma have not brought unequivocal results, and thus this issue remains controversial. Antibiotic use, known to increase asthma risk, may be involved in this relationship. The objective of this study was to assess the influence of breastfeeding duration on obesity and asthma risk in childhood and to test a mediating role of antibiotic use in infancy.A cross-sectional anthropometric and questionnaire study was conducted on 1,277 schoolchildren 8 years of age. Data on weight status, asthma, breastfeeding duration, antibiotic administration in infancy, socioeconomic status, and lifestyle were analyzed. Multivariate standard and logistic regression and mediation analyses, controlling for confounders, were applied.Total duration of breastfeeding was negatively related to the child's body mass index (p=0.038), fat percentage (p=0.030), and obesity risk (p=0.032). Dropping the variable of antibiotic use from the model made the breastfeeding duration a significant predictor of low asthma risk (p=0.027). Antibiotic treatment mediated the relationship between breastfeeding duration and asthma risk (Sobel's z=-2.61, p=0.009).Our findings support protective effects of longer duration of breastfeeding against obesity and asthma. We propose a new mechanism for a relationship between breastfeeding and asthma: shorter breastfeeding compromises infant health and thereby leads to antibiotic treatment, which in turn increases the risk of asthma.

This paper presents the application of the Vision Virtuelle method ininstruction within the scope of the fluency and expressiveness of communicating inPolish Sign Language. It also presents the advantages resulting from the fluent useof the sign language and situations in which such a communication style is crucialto the quality of communication., W artykule omówione zostało zastosowanie metody Vision Virtuelle w nauczaniu płynności i ekspresywności przekazywania komunikatu w języku migowym. Przedstawione zostały również korzyści płynące z płynnego migania oraz sytuacje, w których taki styl komunikowania się jest kluczowy dla jakości porozumiewania się.

The low proportion of waist to hip size in females is a unique and adaptive human feature. In contemporary human populations, the waist-to-hip ratio (WHR) is negatively associated with women’s health, fecundity, and cognitive ability. It is, therefore, hypothesized that men will prefer women with low WHR. Although this prediction is supported by many studies, considerable disagreement persists about which WHR values are the most attractive and the importance of WHR for attractiveness of the female body. Unfortunately, the methods applied thus far are flawed in several ways. In the present study, we investigated male preferences for female WHR using a high precision assessment procedure and digitally manufactured, high quality, anthropometrically informed stimuli which were disentangled from body mass covariation. Forty men were requested to choose the most attractive silhouette consecutively from six series (2 levels of realism × 3 levels of body mass), each consisting of 26 female images that varied in WHR (from .60 to .85 by .01). Substantial inter-individual variation in the choices made was observed. Nevertheless, low and average WHR values were chosen more frequently than above-average values or values below the normal variation of the trait. This preference pattern mirrors the relationship between WHR and mate value, suggesting that the preferences are adaptive.

Body mass index and waist–hip ratio are related to human health and both play a role in mate choice. However, previous research is inconsistent as to what body mass index and waist–hip ratio values are preferred in women and what the relative importance of body mass index and waist–hip ratio for attractiveness is. Here, we made several methodological refinements to obtain reliable estimations. Participants (Poles) indicated the most attractive woman from a set of digitally manipulated high-quality silhouettes varying orthogonally in body mass index and waist–hip ratio and viewed from behind to exclude effects of the breast size. Then, each participant chose the more attractive silhouette from pairs in which one figure deviated from his/her ideal in body mass index and the other in waist–hip ratio. Both sexes preferred underweight women (body mass index = 17.3) with accentuated waist (waist–hip ratio = 0.66 for female and 0.70 for male judges). These represent preferences for unhealthy body mass and healthy body shape. Furthermore, body mass index proved twice as important for attractiveness as waist–hip ratio, even though literature data indicate that waist–hip ratio is at least as important for health as body mass index. We discuss the obtained pattern of preferences from the perspective of evolutionary psychology.

Although people we meet in real life are usually seen in motion, research on facial attractiveness has predominantly been conducted on static facial images. This raises a question about ecological validity of results obtained in such studies. Recently, several studies endeavoured to determine the concordance between attractiveness of faces seen on photos and video clips, but their results are markedly divergent, frequently indicating no concordance. In the present study, the association between attractiveness of facial images and clips was tested on a larger sample than has previously been reported (106 females, 102 males), and features under the face owner's control (scalp and facial hair, makeup, mouth expression) were controlled for. Two types of facial images were used: photographs and frames extracted from films. Correlation coefficients between attractiveness of static and dynamic faces were high (about 0.7), did not depend on facial sex or image type (photograph/frame), and did not diminish when the covariates were controlled for. Furthermore, the importance of facial averageness, femininity/masculinity, symmetry, fattiness, skin health, and mouth expression for attractiveness proved similar for static and dynamic stimuli. This leads to the optimistic conclusion that results of studies relying on attractiveness assessments of static facial images are ecologically valid.

Theoretical and empirical studies suggest that phenotypic averageness is a sign of an individual's high biological quality. The averageness should therefore be preferred in mates. A condition for such preference is the knowledge of average phenotype in the population. It is envisaged that an individual develops a neural template of typical phenotype on the basis of perceptual experience with images of conspecifics, and the template is then used in attractiveness assessments of potential partners. Regrettably, studies supporting this view are lacking. In the present study, adult male competitive swimmers and men who did not partake in swimming assessed the attractiveness of female silhouettes with proportions typical for swimmers or non-swimmers. Because swimmers see other swimmers relatively frequently, we hypothesize that they prefer swimmer-like female silhouettes more strongly than non-swimmers do. The analysis supports this hypothesis, suggesting that mere visual experience shapes a neural template of a silhouette, which subsequently serves as a reference for attractiveness evaluations.

Although attractiveness of the human hand seems to be of some importance in the social and mating context, it has attracted little scientific interest thus far. Here, we investigated physical determinants of hand attractiveness and its associations with facial appeal. Photographs of faces and the dorsal and ventral side of hands of young women and men were measured and assessed for attractiveness and several other features. Typicality and femininity of shape, perceived fattiness and skin healthiness, the appearance of nail vicinity, and grooming influenced hand attractiveness in men and women. Hand and facial attractiveness were correlated with each other for each sex. This relationship was mediated by shape typicality and fattiness in men and by grooming and, possibly, fattiness in women. Results are discussed from an evolutionary psychology perspective with special reference to biological signaling and mate selection.

The correlation of physical attractiveness in romantic partners has been widely documented. However, it has also repeatedly been demonstrated that people are largely unaware of their own attractiveness, which raises the question about the mechanism responsible for the within-pair matching. One hitherto unexplored possibility is that low accuracy in attractiveness self-assessments results from methodological drawbacks. Participants were usually asked to rate their attractiveness on a numeric scale, and independent judges evaluated them on the basis of facial photographs. We hypothesized that the accuracy of self-assessment may be increased if (1) participants and judges evaluate the same characteristic, e.g., both groups assess facial attractiveness, (2) own attractiveness is estimated in a comparative manner (with reference to attractiveness of other individuals) rather than by abstract numbers, (3) judges rate attractiveness of people as seen in video clips rather than in photographs. To test these hypotheses we photographed and videotaped faces of 96 women and 78 men. Independent judges rated attractiveness from these photographs and video clips, and the participants assessed own attractiveness in several ways. None of the above hypotheses was confirmed by statistical analysis. We discuss how the within-pair matching in attractiveness can arise, given such poor awareness of own appeal.

Objectives: The relationship between season of birth and various physical and psychological outcomes was reported in many studies, although the underlying mechanism still remains unrecognized. The aim of this study was to explore the season-of-birth effect on body size in the sample of 1,148 eight-year-old Polish urban children and propose the mechanism responsible for this effect. Methods: The children were examined three times at their birthdays and at two cross-sectional surveys. Effects of the season of birth were checked by fitting the cosine function to empirical values and by comparison between two groups born in different periods of the year. Results: Data gathered at three examinations led to the same results: season-of-birth effect occurred only in boys and only in those relatively shortly breastfed and/or descended from the families of low-socioeconomic status. Specifically, the individuals born in October–April were taller (by 2–3 cm), heavier (by 2–3 kg), and fatter than those born in May–September. Conclusions: The following explanatory mechanism has been formulated: insolation in Poland is minimal in November–February (winter period), and so ultraviolet absorption and vitamin D production is then the lowest. Vitamin D regulates embryo's cellular differentiation, and its deficiency triggers permanent developmental changes. Therefore, individuals conceived in autumn (i) are at the greatest risk of early vitamin D deficiency, (ii) are born in summer, and (iii) are relatively small in their further lives. The contribution of low-socioeconomic status, short breastfeeding, and being a male to the occurrence of the season-of-birth effect is also discussed. Am. J. Hum. Biol., 2010. © 2010 Wiley-Liss, Inc.

Despite numerous studies on perception of facial attractiveness in adults, preferences in adolescents remain poorly characterized. The aim of present study was to explore facial preferences in boys at early adolescence (11-13 years old) and compare them with preferences of men. All males evaluated the same 30 female faces, which were also assessed by independent judges for several perceived features. Regardless of age, boys assessed attractiveness much the same as men, and the strengths of their preferences for specific facial features were similar to those of men. The pubertal maturity (calculated on the basis of the presence of pubic hair at two sessions spaced ten months apart) correlated positively with strength of preference for several facial features (specifically: maturity, sexiness, marital appearance and friendly appearance). This remained true even after controlling for age and psychosexual development, suggesting that sex hormones are involved in the development of facial preferences in pubescent boys.

The aim of the present paper was to evaluate the current state of knowledge on the perception of facial attractiveness and to assess the opportunity for research on poorly explored issues regarding facial preferences. A theoretical framework of research problems was proposed, within which the current state of knowledge on each topic was estimated. The analysis proved that a disproportional amount of research concerned several topics, while many other topics were addressed by few studies, the results of which being sometimes contradictory. Next, possible obstacles to more comprehensive research are discussed. This leads to the conclusion that the obstacles do not severely hinder investigations of most poorly studied problems. The results of the author's recent studies on some of these topics are also briefly reported. In spite of thousands of studies conducted, facial attractiveness research may be regarded as rather poorly progressed, although prospects for it are good.

This review embraces the following topics: intra- and inter-populational variation of facial preferences, relationship between facial attractiveness and mate value, biological and social effects of the perception of facial attractiveness, credibility of the adaptive perspective on facial preferences, and the phylogeny of facial attractiveness. Its main conclusions are as follows: (1) Many sources of inter-individual variation in assessments of facial attractiveness have been identified, e.g., the age, sex, biological quality, physiological state, personality, and living situation of the judge, as well as previously observed faces, physical similarity of the focal face to the judge's face, and acquaintance with and knowledge of the face owner. (2) Inter-populational consistency in perception of facial attractiveness is substantial and possesses both a biological and a cultural basis. (3) Facial attractiveness is a reliable cue to biological quality of the face owner, e.g., better parasite resistance, physical fitness, reproductive fitness, longevity, less mutational load, higher intelligence and better mental health. (4) Facially attractive people have more sexual partners, marry at a younger age, and remain single less frequently. Thereby, they have higher reproductive success than unattractive individuals. (5) As a whole, research supports the thesis that facial preferences are adaptive, that is, they evolved during the course of biological evolution because they assisted an individual in choosing a mate with good genes or a good personality.

This review covers universal patterns in facial preferences. Facial attractiveness has fascinated thinkers since antiquity, but has been the subject of intense scientific study for only the last quarter of a century. Many facial features contribute to facial attractiveness: Averageness and symmetry are preferred by males and females, probably because they signal genetic quality and developmental stability. Men prefer highly feminized female faces because they reflect high estrogen levels and low testosterone levels. This indicates that the woman is reproductively healthy. Women, on the other hand, prefer a moderate level of male facial masculinity, since facial masculinity that is too pronounced signals high level of testosterone and, thereby, a poorly developed pro-family personality. In women, facial hair is detrimental to facial attractiveness. In men, the effect is not consistent. Faces with a clear complexion are attractive to both men and women. Men prefer light and smooth skin in women. Positive facial expressions also enhance facial attractiveness. Many factors, in particular skin condition and facial proportions, affect perceived age, which is an important component of facial attractiveness. Men in particular strongly prefer youthful-looking female faces. Facial preferences enable an individual to recognize reproductively fit mates. Therefore, facial preferences are adaptive, although non-adaptive mechanisms related to general brain function also play a role.

Despite numerous studies on perception of facial attractiveness in adults, preferences in adolescents remain poorly recognized. The aim of present study was to explore facial preferences in girls at early adolescence (11-14 years old) and compare them with preferences of women. All females evaluated the same 30 male faces, which were also assessed by independent judges for several perceived features. Regardless of age, girls assessed attractiveness much the same as women, and the strengths of their preferences for specific facial features were similar to those of women. Except for the youngest girls, pubertal maturity (measured as the time elapsed since the menarche and breast development) correlated positively with the similarity of the girls' attractiveness evaluations to those of adult women and with strength of preference for cues to good biological quality (skin healthiness and sexy appearance). This remained true even after controlling for age and psychosexual development, suggesting thus that sex hormones are involved in development of facial preferences in pubescent girls.

The issue of cultural universality of waist-to-hip ratio (WHR) attractiveness in women is currently under debate. We tested men's preferences for female WHR in traditional society of Tsimane'(Native Amazonians) of the Bolivian rainforest (N = 66). Previous studies showed preferences for high WHR in traditional populations, but they did not control for the women's body mass.We used a method of stimulus creation that enabled us to overcome this problem. We found that WHR lower than the average WHR in the population is preferred independent of cultural conditions. Our participants preferred the silhouettes of low WHR, but high body mass index (BMI), which might suggest that previous results could be an artifact related to employed stimuli. We found also that preferences for female BMI are changeable and depend on environmental conditions and probably acculturation (distance from the city). Interestingly, the Tsimane' men did not associate female WHR with age, health, physical strength or fertility. This suggests that men do not have to be aware of the benefits associated with certain body proportions - an issue that requires further investigation.

Previous studies suggest that human facial attractiveness is culturally universal. As they were conducted among Western populations and populations strongly influenced by the Western culture, it is not obvious if the preferences would also be the same in populations isolated from this culture. It is also not certain if the agreement would be the same in the case of attractive and unattractive faces. In the presented study participated 103 people from the Yali tribe (Papua, Indonesia) and 99 Poles. Their task was to choose the most attractive and unattractive face of the opposite sex from a set of 4 pictures (one attractive, one unattractive and two average faces of Polish people chosen in a pre-test). We showed significant cross-cultural differences in attractiveness preferences and similarities in choices of unattractive faces. We speculate that across cultures unattractiveness could be assessed on the basis of the same cues to health and biological quality. Attractiveness criteria seem to be more complex, specific to each population, and dependent on the population’s ecological conditions and morphological characteristics. Agnieszka Sorokowska

Although scientific interest in facial attractiveness has developed substantially in recent years, few studies have contributed to our understanding of the ontogeny of facial preferences. In this study, attractiveness of 30 male faces was evaluated by four female groups: girls at puberty, nonpregnant and pregnant young women, and middle-aged women. The main findings are as follows: (1) Preference for sexy-looking faces was strongest in young, nonpregnant women. (2) Biologically more mature girls displayed more adultlike preferences. (3) The intragroup consistency for postmenopausal women was relatively low. (4) In terms of the preference pattern, pregnant women were more similar to perimenopausal women than they were to their nonpregnant peers. (5) Preference for youthful appearance decreased with the age of the women. I argue that the life history of female preferences for male faces is, to a large extent, hormone-driven and underpinned by a set of evolutionary adaptations.

Although attractiveness of the human hand is of significance in the social and mating context, thus far it has attracted little scientific interest. In this study, young women and men were presented with pairs of digitally manipulated images of opposite-sex hands and asked to indicate the hand perceived to be the more attractive in each pair. The hands within a pair differed from one another by a single feature: shape averageness, femininity, finger length, second-to-fourth-digit ratio, or skin smoothness. All these features, with the exception of the digit ratio, were shown to increase hand attractiveness in each sex in both dorsal and ventral views. Skin smoothness was preferred more strongly in female than in male hands. Women also tended to prefer medium degrees of shape femininity and skin smoothness in male hands compared to both high and low levels. Adaptive and non-adaptive (related to perceptual bias) mechanisms underlying these preferences are discussed.

This study investigated a hypothesis of dependence of child height and weight on the month of their birth. The sample comprised 1,241 subjects, 568 boys and 673 girls, age 6-20 years, from villages in Olsztyn Province, Northeast Poland. Individuals' height and weight data were standardized by sex and age to allow grouping of individuals born in the same month irrespective of their sex and age at examination. Subjects born in October to March proved to be significantly taller and heavier than those born in April to September. The magnitude of differences between the semiannual groupings equaled 13.1% of a standard deviation (SD) in height (P = 0.03) and 14.2% of SD in weight (P = 0.02). The month-of-birth effect was much stronger for children characterized by high socioeconomic status, where these differences amounted to 39.1% of SD in height (P = 0.02) and 49.4% of SD in weight (P = 0.01). There were no regular changes of the effect with age and no differences between the sexes were found. Fitted cosine functions identified the highest values of examined traits for individuals born in December with the lowest values being found in those born in June. Possible explanations of the month-of-birth effect are considered in terms of age categorizing, seasonal variety of growth rates, as well as birth-related or conception-related global, hemispheric, and local factors. This study rejects the first two possibilities and suggests this effect requires further research to be conducted in various geographical locations, climates, and cultures, on humans as well as on other species.

The Capra genus is sexually dimorphic, males are substantially bigger than females, they fight for mating privileges and sometimes even form harems. Thus Capra genus meets the assumptions of the Trivers-Willard hypothesis. However, in case of the domestic goat Capra hircus their reproduction is man-managed. We assessed whether maternal hornedness, maternal and paternal breed and age, maternal birth year, litter size, previous year offspring sex, and litter birth year influenced offspring sex ratio in the domestic goat. We examined 268 litters born in the years 1997–2002 at the Experimental Farm in Złotniki. The statistic methods used were logistic regression and Spearman rank correlation. The offspring sex ratio in the herd differed significantly from unity: 55.8% kids were females, p < 0.01. The factors that significantly influenced offspring sex ratio were maternal hornedness and maternal birth year. Horned dams (occupying high positions in the social hierarchy) produced fewer daughters (52.2% of offspring) than hornless nannies (62.2%). The fact that dams born later produce more daughters can be connected with their origin from different farms and worse environmental conditions in Złotniki in the consecutive years (because of the Experimental Farm financial problems). Moreover, Spearman rank correlation between sex ratio in the first and in the second litter was marginally significant and negative (R = −0.25, p = 0.061).