Pheromones as honest signals in mate selection--论文代写范文精选

考虑到信号的信息减少了错误,并允许更可靠择偶的决定，对女性来说，面部魅力和性感的身体气味呈明显的正相关关系。对于男人来说,情况是不同的。下面的essay代写范文进行详述。

Abstract 
It is presumable that human scent, apart from the above-mentioned functions, could - like other cues in mate selection - also signal aspects of reproductive fi tness. Several studies have found that bodily and facial symmetry play a role in attraction and thus in choice criteria for human mating. Symmetry is believed to signal developmental stability, which refers to an individual’s ability to cope with genetic and environmental perturbations during early development. Recent research has focused on the signifi cance of developmental stability as mate choice-criterion. Sex steroid hormone dependent human body odor could transmit information about an individual’s developmental stability as an additional, redundant olfactory signal. Since olfactory and visual cues have different physiological roots, the signaling errors are likely to be uncorrelated. 

Thus, taking the information of both signals into account reduces the error and allows much more reliable mate choice decisions (see [94] for details). Rikowski and Grammer [95] compared ratings of body odor, attractiveness, and measurements of facial and bodily asymmetry of 16 male and 19 female subjects. Subjects wore a T-shirt for three consecutive nights under controlled conditions. One group of opposite-sex raters then judged the odor of the T-shirts, and another group evaluated portraits of the subjects for attractiveness. Additionally, bodily and facial symmetry of the odor-donors were measured. Facial attractiveness and sexiness of body odor showed a signifi cant positive correlation for female subjects. 

In men, the situation was different. Positive associations between body odor and attractiveness and negative associations between odor and bodily asymmetry could only be found if female odor raters were in the most fertile phase (i.e., ovulatory phase) of their menstrual cycle. Thus, simply put, ovulatory women preferred the scent of symmetry. This effect, replicated by Gangestad & Thornhill [96], could be explained by the above-mentioned female preference of androstenone around ovulation. Metabolic pathways suggest a link between α-androstenes and testosterone [97]. It is presumed that only individuals with high immunocompetence can afford the immune-suppressing effect of a high testosterone level [98]. Immunocompetence appears to correlate with high developmental stability [99]. 

Thus, human pheromones could indeed be regarded as honest signals for human mate choice based on the testosterone-immunocompentence-developmental stability link to pheromone production. In humans, female olfactory preferences also seem to induce disassortative mating for components of the major histocompatibility complex (MHC) as is observed in other mammals [100]. In other words, olfactory cues may be able to refl ect parts of an individual’s genome, and body odor seems to infl uence female mate choice in order to fi nd a partner who possesses fi tting MHC-dependent immune system components. Simply put, ovulatory women seem to prefer the scent of genetic diversity. Indeed, both women who are not taking oral contraceptives, and men rate similar genetically determined odors as less attractive than dissimilar genetically determined odors. 

Thus, not only are men and women able to distinguish among genetically distinct, self versus non-self odors, they prefer the scent of non-self (i.e., genetic diversity) [101]. Men and women with shared markers of genetic diversity also select perfumes that may amplify body odor that is linked to their genetic diversity [102]. Johnston, Hagel, Franklin, Fink and Grammer [103] propose that male facial attractiveness is mediated by hormones, and generally support a hormonal theory of facial attractiveness dependent on the interaction between visually displayed hormone markers and the hormonal state of the viewer. There is no biological pathway that directly links visual input either to neuroendocrine function, or to the hormonal state of the viewer, and male and female visual systems are not sexually dimorphic. 

Accordingly, the means and biological mechanisms by which sexually dimorphic, hormone-dependent facial features become attractive have yet to be detailed. However, the olfactory pathways link the hormonal state of the “viewer” to chemical signals of reproductive fi tness that correlate well with the degree of hormone-dependent, sex ually dimorphic facial features. For example, higher T levels correlate with the visual appeal of a “stronger” jaw. The interaction of these visually displayed hormone markers of reproductive fi tness and the effects of the hormones on pheromone production and distribution suggest that the effects of pheromones on reproductive neuroendocrine function might provide a critical, well-detailed, mammalian link between hormone-mediated facial signals and what we consciously perceive as facial attraction. 

We would be remiss if we failed to address yet another aspect of what is most commonly believed to be visually perceived physical attraction: the waistto-hip ratio (WHR) Sex steroid hormones control regional fat distribution [104], which interacts with reproductive control mechanisms. For example, fat tissue converts androgens to estrogens [105]. Circulating E levels appear to lower WHR, while circulating T levels appear to increase WHR, which is believed to signal reproductive fi tness in women, and perhaps in men [106]. In addition, high levels of LH and FSH as well as estradiol levels are linked to lower WHR and to the earlier pubertal endocrine activity of females. However, the conscious or unconscious mechanisms linked to the perception of WHR and its link to physical attractiveness, have not been detailed. Presumably, these mechanisms exist cross-culturally, but they have defi ed explanation. 

The conditioning of visually perceived physically attractive WHR by association with steroid hormone-dependent chemical cues (e.g., human pheromones) seems to be a very likely explanation for the increased desirability of men and women whose weight and height are proportionate. Each example above, of symmetry, genetic diversity, hormone-mediated facial attraction, and of WHR, has some as yet undetermined link to what we visually and consciously perceive to be attractive. The simplistic statement, we think about what we see and decide whether or not it is attractive, summarizes these examples. In contrast, other mammals don’t think but somehow manage both to decide and to choose for genetic and hormonal traits of reproductive fi tness. In other mammals, links among olfactory acuity and specifi city, genetically determined odors, and hormones and odor production provide clear examples of affective primacy, like the chemical cues that affect GnRH-directed hormone responses in limbic structures. This impact of these chemical cues on hormones allows for rapid responses, and accurate choices that do not require cognition. For example, unconscious odor cues link genetic diversity and all aspects of hormone-mediated mate choice. Affective primacy is best explained by mammalian, including human, olfactory acuity and specifi city. The explanatory power of visual input pales by comparison.

Conclusion 
We have addressed several aspects of what is consciously perceived to be visual attraction both from an ethological and neuroendocrinological approach. In other mammals, the olfactory link among hormones, pheromones, and a conspecifi c’s hormones and behavior would readily establish that visually perceived facial attractiveness, bodily symmetry, attractive WHRs, and genetically determined HLA attractiveness, are due to the neuroendocrinological conditioning of visual responsivity to olfactory stimuli. Yet, we have merely scratched the surface with regard to the pheromonal basis of human mate choice. As we can “see”, the model of humans being primarily visual creatures may require some reconsideration. Human life and interactions are infl uenced by pheromones whether or not affect or effect are part of our consciousness. The affective hormonal reactions caused by olfaction and pheromones dominate social interaction, and these affective reactions may be the primary infl uence on social interactions. Human pheromones have more potential than any other social environmental sensory stimuli to infl uence physiology and, therefore, behavior. Predictably, we will soon address other aspects of human attraction, and social confounds such as the paraphillias – and even sexual orientation in future discourse. Finally, we might even address the obvious question of how our everyday social lives and future human reproductive success will be affected by the modern striving for cleanliness and the reduction of natural body odor.（essay代写)

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