Cue-based estimates of reproductive value explain women's body attractiveness

Women's body attractiveness is influenced by specific anthropometric cues, including body mass index (BMI), waist-to-hip ratio (WHR), waist-to-stature ratio (WSR), and shoulder-to-waist ratio (SWR). Despite the existence of multiple functional hypotheses to explain these preferences, it remains unclear which cue-based inferences are most influential in regulating evaluations of women's body attractiveness. We argue that (i) the common link to the morphological cues that influence women's body attractiveness is that they all reliably indicate high reproductive value (as defined by youth and low parity); and (ii) ancestrally, selection pressures related to tracking between-women differences in reproductive value would have been among the strongest acting on adaptations for body evaluation. An empirical study then tested the resulting prediction that cue-based estimates of reproductive value function as powerful regulators of women's body attractiveness judgments. Subjects viewed standardized photos of women in swimsuits (with heads obscured), and were assigned to either estimate components of their reproductive value (age or number of offspring) or rate their attractiveness. Structural equation modeling revealed that a latent variable capturing estimated reproductive value was almost perfectly correlated with a latent variable capturing body attractiveness. Moreover, unique associations of women's BMI, WHR, and WSR with their body attractiveness were entirely mediated via estimated reproductive value. These findings provide strong support for the longstanding hypothesis that women's body attractiveness is primarily explained by cue-based estimates of reproductive value – expected future utility as a vehicle of offspring production.     

Face and voice attractiveness judgments change during adolescence

Attractiveness judgments are thought to underpin adaptive mate choice decisions. We investigated how these judgments change during adolescence when mate choice is becoming relevant. Adolescents aged 11–15 evaluated faces and voices manipulated along dimensions that affect adults' judgments of attractiveness and that are thought to cue mate value. Facial stimuli consisted of pairs of faces that were more or less average, more or less feminine, or more or less symmetric. The adolescents selected the more average, symmetric, and feminine faces as more attractive more often than chance, but judgments of some facial traits differed significantly with rater age and sex, indicating a role of development in judgments of facial cues. Vocal stimuli consisted of pairs of voices manipulated to raise or lower perceived pitch. The older but not younger girls selected the lower-pitched male voices as more attractive at rates above chance, while the younger but not older boys selected the higher-pitched female voices as more attractive. Controlling for rater age, increased pubertal development was associated with increased selection of lower-pitched boys' voices by girls and decreased selection of feminized male faces by boys. Our results are the first to demonstrate that adolescents show somewhat similar attractiveness judgments to adults in age-matched stimuli and that age, sex, and pubertal development have measurable effects on adolescents' attractiveness judgments. They suggest that attractiveness judgments in humans, at least for some traits, are facultatively calibrated to the individual's life stage, only reaching adult values upon sexual maturity when mate choice decisions become relevant.     

Slug foraging behaviour: Attraction to food items from a distance

Slug foraging paths recorded using time lapse video techniques under infra-red light were fitted to a correlated random walk model. Analyses were carried out on slugs in arenas where no food was present, as well as those containing commercial molluscicides at two rates of application. Slugs were found to search randomly in empty arenas and those containing commercial metaldehyde baits, but deviated from random search patterns when in the presence of commercial methiocarb bait. Differential attraction from a distance is suggested as a cause of these differences.     

Visitor behavior in the National Zoo's reptile house

Visitor behavior was evaluated in the National Zoo's reptile house. Nearly 600 visitors were tracked; time spent in the house and time spent looking at exhibits were noted. These parameters were investigated by sex, age, and type of visitor grouping. The most looked-at exhibits were determined. For 573 visitors, the mean time in the reptile house was 14.7 minutes. Only about 8 minutes was spent looking at exhibits, and this time was strikingly similar for age, sex, and group type. Time spent looking at exhibits was negatively correlated with visitor density. Amphibians and lizards were looked at for less time than snakes and turtles. Crocodilians were looked at longer than the other taxonomic groups, while larger animals in all groups were looked at longer than smaller ones. This study and other similar studies imply that the public does not respond to exhibits with the expected interest and enthusiasm. It is hoped that with a better understanding of the public through research, zoo staff can improve visitor interest in the exhibits.     

Effects of allatectomy and ovariectomy on cuticular hydrocarbons in Calliphora vomitoria (diptera)

The relationships between female attractiveness, cuticular hydrocarbons, and levels of juvenile hormone and ecdysteroids were studied in Calliphora vomitoria. The experiments were conducted at 48 and 72 h post-emergence, according to attractiveness appearance and increase. The 48-h-old allatectomized females were less attractive than the control females, whereas no changes occurred either in cuticular hydrocarbons total mass production or in the different hydrocarbon families. However, the 72-h-old allatectomized females were more attractive than the control females, and, in relative proportions, allatectomy led to an increase in monomethylalkanes and a decrease in n-alkanes. Only at 48 h were the ovariectomized females less attractive than the control females and did ovariectomy increase the relative proportions of monomethylalkanes. At 72 h, ovariectomy did not influence female attractiveness, but it decreased the total cuticular hydrocarbon production. Allatectomy and ovariectomy significantly decreased ecdysteroids levels at 48 and 72 h. Ovariectomy did not affect juvenile hormone production. These results suggest that attractiveness and cuticular hydrocarbon synthesis could be under the direct control of ecdysteroids and the indirect influence of juvenile hormone. © 1994 Wiley-Liss, Inc.     

Scototaxis and shape discrimination in the female cricket Acheta domesticus in an arena and on a compensatory treadmill

ABSTRACT. The scototactic responses of adult female Acheta domesticus L. were tested toward various shaped targets in an orientation arena and on a compensatory treadmill. In an arena, crickets oriented toward dark targets (positive scototaxis) if they had horizontal visual angles ≥30, and if the vertical dimensions of the target was ≤ its horizontal dimension. Unattractive targets did not result in negative scototaxis but caused crickets to orient randomly with no net directionality. When complex targets were composed of two or more simple rectangular targets which had been previously defined as attractive or unattractive, intermediate responses were obtained. Crickets oriented less toward complex targets than toward simple attractive targets, but oriented more than toward simple unattractive targets. The responses of a female cricket toward an attractive target can be modified by the presence of a chemical signal emitted by previously tested females. When the signal is present females are less likely to orient toward a target that would otherwise be very attractive. This effect was not as great when the females being tested were taken directly from densely populated colonies.
When running on a compensatory treadmill, female crickets exhibit scototactic tendencies similar to those displayed in the arena. When tested on the treadmill over long periods, the amount of time spent orienting toward an attractive target increased.     

Olfactory cues modulate facial attractiveness

We report an experiment designed to investigate whether olfactory cues can influence people's judgments of facial attractiveness. Sixteen female participants judged the attractiveness of a series of male faces presented briefly on a computer monitor using a 9-point visual rating scale. While viewing each face, the participants were simultaneously presented with either clean air or else with 1 of 4 odorants (the odor was varied on a trial-by-trial basis) from a custom-built olfactometer. We included 2 pleasant odors (geranium and a male fragrance) and 2 unpleasant odors (rubber and body odor) as confirmed by pilot testing. The results showed that the participants rated the male faces as being significantly less attractive in the presence of an unpleasant odor than when the faces were presented together with a pleasant odor or with clean air (these conditions did not differ significantly). These results demonstrate the cross-modal influence that unpleasant odors can have on people's judgments of facial attractiveness. Interestingly, this pattern of results was unaffected by whether the odors were body relevant (the body odor and the male fragrance) or not (the rubber and geranium odors).     

What is behind the variation in mate quality dependent sex ratio adjustment? – A meta‐analysis

Theory predicts that parents adjust the sex ratio of their brood to the sexually selected traits of their mate because the reproductive success of sons may be more dependent on inherited paternal attractiveness than that of daughters. Empirical studies vary in terms of whether they support the theory, and this variation has often been regarded as evidence against sex ratio adjustment or has been ascribed to methodological differences. Applying phylogenetic meta‐analyses, we aimed to find biological explanations for the variation observed in songbirds. In particular, we tested the role extra‐pair paternity, because infidelity occurs in the majority of these species and may reduce the adaptive value of adjusting brood sex ratio to the phenotype of the social mate. However, we found that the variation in effect sizes was unrelated to the proportion of extra‐pair paternity. Thus future studies should consider that mate quality dependent sex ratio adjustment may be driven by direct (material) rather than indirect (genetic) benefits. We also tested if the effect sizes are influenced by whether the focal male trait is indeed under sexual selection as it is assumed by the sex allocation theory. We found that for male traits with proven role in sexual selection, effect sizes significantly differed from the null expectation of random production of sons and daughters. For male traits with only presumed sexual role in sexual selection, the deviation from the null expectation was less convincing, and the effect sizes were significantly smaller. This result indicates that studies that neglect the assumptions of the hypotheses concerned, may lead to the underestimation of the mean effect size and, eventually, false conclusions.     

笑弧在面部宽窄不同的个体中对微笑美学的影响

目的:研究面部宽窄不同女性的笑弧对微笑美学的影响。方法:选取女性正位微笑像1张,应用Adobe Photoshop CS5软件对笑弧和面部宽窄进行修改,由正畸医生和非专业人士对照片的微笑魅力值进行评判。结果:笑弧和面部宽窄程度在魅力微笑的判别中无交互作用(P0.05)。两组对理想的笑弧、略窄的面型和适宜的面型的魅力微笑判别分值较高(P0.05)。非专业人群中,在三种笑弧中,除了很窄的面型,魅力微笑的分值均随着面型的增宽降低(P0.05)。专业人群中,对于平坦的笑弧,除了很宽的面型,魅力微笑的分值随着面型的增宽而增加(P0.05);对于理想的笑弧,魅力微笑的分值随着面型的过宽或过窄而降低,但仍高于其他两种笑弧(P0.05);对于弯曲的笑弧,除了很窄的面型,魅力微笑的分值随着面型的增宽而降低(P0.05)。结论:笑弧和面部宽窄对魅力微笑的判别具有一定影响。不同人群对笑弧及面部宽窄与微笑美学的认识也存在差异,在正畸治疗中应根据患者面部宽窄合理的选择治疗方案。     

Changing perceptions of attractiveness as observers are exposed to a different culture

It has been suggested that certain physical cues can be used to predict mate quality and that sensitivity to these cues would therefore be adaptive. From this, it follows that in environments where the optimal values for these features differ, the attractiveness preferences should also be different. In this study, we show that there are striking differences in attractiveness preferences for female bodies between United Kingdom (UK) Caucasian and South African Zulu observers. These differences can be explained by different local optima for survival and reproduction in the two environments. In the UK, a high body mass is correlated with low health and low fertility, and the converse is true in rural South Africa. We also report significant changes in the attractiveness preferences of Zulus who have moved to the UK. This suggests that these preferences are malleable and can change with exposure to different environments and conditions. Additionally, we show that Britons of African origin, who were born and who grew up in the UK, have exactly the same preferences as our UK Caucasian observers. These results suggest that humans have mechanisms for acquiring norms of attractiveness that are highly plastic, which allow them to track different ecological conditions through learning.     

Male preferences for female waist‐to‐hip ratio and body mass index in the highlands of Papua New Guinea

One hundred men, living in three villages in a remote region of the Eastern Highlands of Papua New Guinea were asked to judge the attractiveness of photographs of women who had undergone micrograft surgery to reduce their waist‐to‐hip ratios (WHRs). Micrograft surgery involves harvesting adipose tissue from the waist and reshaping the buttocks to produce a low WHR and an “hourglass” female figure. Men consistently chose postoperative photographs as being more attractive than preoperative photographs of the same women. Some women gained, and some lost weight, postoperatively, with resultant changes in body mass index (BMI). However, changes in BMI were not related to men's judgments of attractiveness. These results show that the hourglass female figure is rated as attractive by men living in a remote, indigenous community, and that when controlling for BMI, WHR plays a crucial role in their attractiveness judgments. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Different impacts of resources on opposite sex ratings of physical attractiveness by males and females

Parental investment hypotheses regarding mate selection suggest that human males should seek partners featured by youth and high fertility. However, females should be more sensitive to resources that can be invested on themselves and their offspring. Previous studies indicate that economic status is indeed important in male attractiveness. However, no previous study has quantified and compared the impact of equivalent resources on male and female attractiveness. Annual salary is a direct way to evaluate economic status. Here, we combined images of male and female body shape with information on annual salary to elucidate the influence of economic status on the attractiveness ratings by opposite sex raters in American, Chinese and European populations. We found that ratings of attractiveness were around 1000 times more sensitive to salary for females rating males, compared to males rating females. These results indicate that higher economic status can offset lower physical attractiveness in men much more easily than in women. Neither raters' BMI nor age influenced this effect for females rating male attractiveness. This difference explains many features of human mating behavior and may pose a barrier for male engagement in low-consumption lifestyles.     

Comparative floral biology of Rhynchospora ciliata (Vahl) Kukenth and R. pubera (Vahl) Boeckeler (Cyperaceae): the role of white involucral bracts in attracting pollinating insects

Although Cyperaceae are considered anemophilous, some species exhibit features that are attractive to pollinators, such as the white UV‐reflecting involucral bracts of Rhynchospora ciliata. But how effective are these conspicuous adaptations? To address this question, we tested the hypothesis that species such as R. ciliata are visited by greater numbers of pollinating insects than similar species with green involucral bracts, such as R. pubera. We compared the floral biology of both species and the number of visits to sympatric populations of each species, associating them with the availability of pollen and the pollination system. We verified that species with white involucral bracts are preferred, because there were more visits to R. ciliata in the first 2 h the flowers were open. The peak visitation in R. pubera was 2 h after the flowers opened, when the pollen of R. ciliata was exhausted. Although the involucral bracts of R. pubera are green, the spikelet scales and anthers are white and reflect ultraviolet light. Overall, flowers of R. pubera exhibit fewer white or reflective surfaces and are probably less conspicuous to a bee than those of R. ciliata. It is possible that R. pubera is a second option for visitors after the first 2 h of anthesis. The two different peaks in visitation minimize interspecific competition for pollinators, suggesting that R. ciliata and R. pubera together could attract more generalist pollinators and, instead of competing, facilitate the pollination of both species. Although R. pubera is autogamous and self‐compatible, both wind and insects are important to its reproductive success.     

Economic principles motivating social attention in humans

We know little about the processes by which we evaluate the opportunity to look at another person. We propose that behavioural economics provides a powerful approach to understanding this basic aspect of social attention. We hypothesized that the decision process culminating in attention to another person follows the same economic principles that govern choices about rewards such as food, drinks and money. Specifically, such rewards are discounted as a function of time, are tradable for other rewards, and reinforce work. Behavioural and neurobiological evidence suggests that looking at other people can also be described as rewarding, but to what extent these economic principles apply to social orienting remains unknown. Here, we show that the opportunity to view pictures of the opposite sex is discounted by delay to viewing, substitutes for money and reinforces work. The reward value of photos of the opposite sex varied with physical attractiveness and was greater in men, suggesting differential utility of acquiring visual information about the opposite sex in men and women. Together, these results demonstrate that choosing whom to look at follows a general set of economic principles, implicating shared neural mechanisms in both social and non-social decision making.     

Mosquito fauna of the Guapiaçu Ecological Reserve,Cachoeiras de Macacu,Rio de Janeiro,Brazil, collected under the influence of different color CDC light traps

The objective of the present study was to identify mosquito fauna and to evaluate whether different light bulb colors influence the attraction of light traps in the Guapiaçu Ecological Reserve. Samples were obtained monthly during the period of February, 2012 to January, 2013. Centers for Disease Control (CDC) light traps with incandescent light bulbs and LED (ultraviolet, blue, green, and red) bulbs were utilized. In total, 8,170 specimens were captured, including 59 species. The presence of Anopheles nimbus (Theobald 1902) and Orthopodomyia fascipes Coquillet 1906 were recorded for the first time in the state of Rio de Janeiro. The green LED trap attracted the highest number of specimens and presented the highest diversity and mosquito average. The blue and green LED traps attracted the highest number of species. However, the differences between lights were not significant. The most common species were Coquillettidia juxtamansonia (Chagas 1907), Culex declarator Dyar and Knab 1906, and Culex ribeirensis Forattini and Sallum 1985.     

Populational differences in attractiveness judgements of male and female faces: Comparing British and Jamaican samples

In the UK and Japan, both men and women prefer somewhat feminised opposite-sex faces, especially when choosing a long-term partner. Such faces are perceived as more honest, caring, and sensitive; traits that may be associated with successful male parental investment. By contrast, women prefer less feminised faces for short-term relationships and when they are near ovulation. As genetic quality may be associated with facial masculinity, women may ‘trade-off’ cues between genetic quality and paternal investment in potential partners. No analogous trade-off has been suggested to influence men's preferences, as both attributions of prosociality and potential cues to biological quality are associated with facial femininity in female faces. Ecological and cultural factors may influence the balance of trade-offs leading to populational differences in preferences. We predicted that Jamaican women would prefer more masculine faces than British women do because parasite load is higher in Jamaica, medical care less common (historically and currently), and male parental investment less pronounced. Male preferences, however, were predicted to vary less cross-culturally, as no trade-off has been identified in female facial characteristics. We constructed masculinised and feminised digital male and female face stimuli of three populations (Jamaican, Japanese, and British) and presented them to men and women in Jamaica and in Britain. The results demonstrated that Jamaican women preferred more masculine male faces than their British counterparts did. Jamaican men tended to prefer more masculine female faces than did British men did, but this effect was complicated by an interaction suggesting that more feminised faces were preferred within culture.     

What Determines Bird Beauty in Human Eyes?

ABSTRACT

Some authors have argued that human preferences for “beautiful” birds may skew the selection of species used to promote conservation programs. This evokes questions about the importance of color, shape, and other appearance traits of bird in affecting human preferences for birds. The aim of this study was to assess the traits affecting human preferences towards all non-passerine and five passerine bird families (n = 102), and to see whether such preferences correspond within a family or are species-specific. Using an Internet survey, we asked 200 human respondents to evaluate pictures of bird species, with two randomly chosen from each family, according to their attractiveness. The respondents were mainly from the Czech and Slovak Republics, but 67 came from other countries (the majority of which were English-speaking). An additional 100 respondents, exclusively from the Czech and Slovak Republics, evaluated the same pictures converted to silhouettes, to test the effect of shape versus color. We included various factors such as morphometric traits (i.e., measurements of body segments and the area the bird silhouette filled in the picture), body weight of the species, and colors, lightness, and saturation of the pictures in the statistical analyses, to help explain any variation in human preferences. We found that human preferences were significantly affected by bird morphology; however, the colors blue and yellow, as well as the overall lightness, were significant as well. The preferences for species belonging to the same family were positively correlated, possibly due to similarity in the body shape of related species. We suggest that finding the traits that determine human preferences toward birds may help conservationists promote a conservation program based on the selection of the correct, scientifically determined, flagship species.