جذابیت صورت مردان: شواهد برای طراحی تطبیقی با واسطه هورمون
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|35622||2001||17 صفحه PDF||سفارش دهید||8064 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Evolution and Human Behavior, Volume 22, Issue 4, July 2001, Pages 251–267
Experimenters examining male facial attractiveness have concluded that the attractive male face is (1) an average male face, (2) a masculinized male face, or (3) a feminized male face. Others have proposed that symmetry, hormone markers, and the menstrual phase of the observer are important variables that influence male attractiveness. This study was designed to resolve these issues by examining the facial preferences of 42 female volunteers at two different phases of their menstrual cycle. Preferences were measured using a 40-s QuickTime movie (1200 frames) that was designed to systematically modify a facial image from an extreme male to an extreme female configuration. The results indicate that females exhibit (1) a preference for a male face on the masculine side of average, (2) a shift toward a more masculine male face preference during the high-risk phase of their menstrual cycle, and (3) no shift in other facial preferences. An examination of individual differences revealed that women who scored low on a “masculinity” test (1) showed a larger menstrual shift, (2) had lower self-esteem, and (3) differed in their choice of male faces for dominance and short-term mates. The results are interpreted as support for a hormonal theory of facial attractiveness whereby perceived beauty depends on an interaction between displayed hormone markers and the hormonal state of the viewer.
In a fraction of a second, the brain of a human male or female can ascertain the physical attractiveness of another person's face Johnston & Oliver-Rodriguez, 1997 and Oliver-Rodriguez et al., 1999. This remarkable feat appears to depend on the delicate interplay between physical markers on the face, perhaps fitness indicators (Miller, 2000), and exquisitely sensitive brains that generate feelings, perhaps fitness monitors (Johnston, 1999), in response to such signals. Support for this model comes from studies that have used various image-processing techniques to systematically manipulate the features and proportions of female facial images and observe the behavioral and/or emotional responses of men and women exposed to such images. The current experiment attempts to evaluate and refine this model by examining how the attractiveness of male and female faces varies with both their displayed hormone markers, and the hormonal state of female viewers, as indicated by their menstrual phase. Early studies suggested that the most attractive female face was the average face in a population Langlois & Roggman, 1990, Langlois et al., 1994 and Langlois et al., 1991. Several experimenters, however, have concluded that the image-processing technique used in these studies may be flawed, and proposed that although the average face is attractive, it is not the most attractive face in a population Alley & Cunningham, 1991 and Johnston, 2000. Strong support for the “non-average” hypothesis comes from Perrett, May, and Yoshikawa (1994), who demonstrated that an average face made by combining random faces is judged to be less attractive than the average of attractive faces drawn from the same sample of faces. Indeed, there is now substantial evidence indicating that attractive female faces are not average, but differ from the average in a systematic manner. More specifically, they possess a shorter, narrower, lower jaw, fuller lips, and larger eyes than an average face Cunningham et al., 1995, Johnston & Franklin, 1993 and Perrett et al., 1994. These specific markers have been shown to be effective across cultures Cunningham et al., 1995 and Perrett et al., 1994, and electrophysiological studies have revealed that they elicit emotional responses in male, but not female, viewers of female faces (Johnston & Oliver-Rodriguez, 1997). Because pubertal bone growth (brow ridges and lower jaw) is stimulated by androgens (Tanner, 1978), and lip fullness parallels estrogen-dependent fat deposits elsewhere on the female body (Farkas, 1981), Johnston and Franklin (1993) have hypothesized that an attractive female face may be displaying hormone markers (high estrogen/low androgen) that serve as reliable indicators of fecundity. In contrast to the research on female facial attractiveness, studies examining the importance of hormone markers on male faces have produced apparently incompatible results. For example, although a number of experimenters have demonstrated that women favor a “masculinized” male face possessing a large jaw and prominent brow ridges and cheekbones Grammer & Thornhill, 1994 and Scheib et al., 1999, other studies have reported that both British and Japanese females prefer a more “feminized” male face with a shorter-than-average lower jaw Penton-Voak et al., 1999 and Perrett et al., 1998. Still others have found that a mixture of mature features (large lower jaw, prominent cheekbones, and thick eyebrows) and neotenous features (large eyes and small nose) is the most desirable configuration of male faces (Cunningham, Barbee, & Pike, 1990). Some of these inconsistencies across studies may result from the different procedures used to generate the male facial stimuli. For example, both studies reporting a preference for feminized male faces used a caricaturing technique to create their masculinized and feminized facial images. Producing a masculinized male face using this procedure involves an algorithm that further exaggerates the differences between an average female and an average male face. This mathematical procedure is based on the assumption that extreme masculine and feminine faces can be produced by a linear extrapolation of the differences between these average faces. However, given that the majority of consistent male–female differences are the result of bone growth, which depends on a complex interaction between androgens, estrogens, and growth hormone, this linear growth assumption may not be valid Grumbach, 2000 and Tanner, 1978. A second consequence of caricaturing is its potential effects on modifying facial symmetry. Average male and female faces are inevitably low in fluctuating asymmetries (traits that differ among individuals but are symmetrical at a population level), so morphs generated between such faces (feminized males and masculinized females) will invariably be quite symmetrical. It is also inevitable, however, that any small deviation from perfect symmetry that exists in either the average male or average female face will be substantially exaggerated in caricatured faces (masculinized males and feminized females). Caricaturing, therefore, is likely to generate feminized male facial images that are more symmetrical than masculinized male images. Because facial symmetry may influence attractiveness Gangestad et al., 1994, Grammer & Thornhill, 1994, Mealey et al., 1999 and Perrett et al., 1999), any observed preference for a feminized or a masculinized male face may be confounded by differences in the symmetry of these faces. The current study attempts to improve on this research methodology by examining preferences for male (and female) faces that have been masculinized (or feminized) on the basis of perceived masculinity (or femininity), rather than employing the caricaturing technique. Low fluctuating asymmetry (FA) is thought to reflect an ability to resist the harmful effects of mutations, parasites, and/or toxins during development (Møller & Swaddle, 1997). Because such resistance is partially heritable (Møller & Thornhill, 1997), there may be important fitness benefits for females who exhibit a preference for such mates. A variety of experimental findings support this hypothesis. Across species, symmetrical males have significantly greater mating success (Møller & Thornhill, 1998), and symmetrical males have been shown to be more desirable and have more sexual opportunities than asymmetrical men Gangestad & Thornhill, 1997 and Thornhill & Gangestad, 1994. In populations lacking widespread contraception and modern medicine, these enhanced sexual opportunities can be translated into more offspring and better health (Waynforth, 1998). However, despite the correlation between symmetry and attractiveness, it appears that human females may not use or even perceive fluctuating asymmetries when judging the attractiveness of male faces (Scheib et al., 1999). Scheib et al. (1999) found that the measured FA of male faces was not only correlated with their attractive ratings, but was also correlated with the attractiveness ratings of a right or left half-face, circumstances where all direct cues to bilateral symmetry are absent. Clearly, their experimental participants did not require explicit cues of bilateral symmetry to make accurate judgments of attractiveness. It appears that the salient cues for attractiveness are apparent on each half of a male's face and their presence is correlated with computed FA, but not perceived symmetry. An examination of the attractive faces led the authors to conclude that the specific features correlated with attractiveness and FA were a longer lower jaw and prominent cheekbones. Keating (1985) also found that the shape of the lower jaw was an important attribute of male facial attractiveness. Using an Identi–Kit methodology, she examined the effects of eye size, lip fullness, brow thickness, and jaw shape on both dominance and attractiveness ratings. As she had predicted, the combination of masculine features (square jaw, narrow eyes, thick eyebrows, and thin lips) enhanced the dominance ratings of male faces, but only a subset of these attributes (square jaw and thin lips) resulted in significantly higher attractiveness ratings. It appears that some high testosterone markers (square jaw) and low estrogen markers (thin lips) influence both the dominance and attractiveness of male faces, but dominance and attractiveness are not identical attributes. Given these prior results, the current study attempts to clarify the role of hormone markers in the perception of dominance and attractiveness, in both male and female facial images. Some of the discrepancy in findings among male attractiveness studies may be a consequence of differences in the participant populations. One potential source of variance is the hormonal status of female participants. Penton-Voak et al. (1999) have shown that females' preferences for male faces changed as a function of the viewer's menstrual phase at the time of testing. Specifically, females tested during the 9 days prior to ovulation (high conception risk group) preferred a less feminized male face than females tested outside of this window (low conception risk group). In a more recent study, using 139 participants who responded to a magazine survey, Penton-Voak and Perrett (2000) reported that women in the high conception risk group were significantly more likely to prefer a masculine face than those in the low conception risk group. The authors interpret their findings as evidence for a conditional mate choice strategy whereby females in the high conception risk group are exhibiting a preference for male facial cues that signal adaptive heritable genetic characteristics, such as immunocompetence. However, these menstrual studies have not shown that the observed change in preference over the menstrual cycle is specific to attractive male faces. Do females' preferences for female faces also change? If so, then the observed effect may simply reflect a general change in mood over the menstrual cycle (Dalton, 1982), rather than a specific adaptation. To explore the generality of the menstrual effect, the current study examines how a variety of different facial preferences (attractive male, attractive female, dominant male, dominant female, etc.) are, or are not, modified by the hormonal state of female viewers. An effect on male facial attractiveness alone would provide strong evidence for complex adaptive design (Williams, 1966). This is the hypothesis that is evaluated in the current study.