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In all human relationships, with respect to interpersonal attraction and interpersonal chemistry, an ever-present amount of “balancing” attraction and repulsion reactionary tendencies function to facilitate the formation and dynamics of human bonding. In stable long-term marriages, for example, 5-to-1 ratio of attraction-to-repulsion functions as a stabilizing ratio, otherwise known as the Gottman stability ratio..  When repulsion tends to predominate at a higher ratio than this, such as 5-to-2, divorce or relationship breakup is inevitable, unless a significant change occurs.
Many researchers naively have assumed that attraction is a unidimensional variable or that attraction alone is the single factor in determining the outcome of a potential bonding relationship. This, however, is a misnomer. Some, for example, will argue that attraction and repulsion are mirror images of one another and that the more we dislike someone or some aspect of someone, the less we like him or her.  In such a conception, then, one’s attraction toward another can vary from extreme attraction to extreme repulsion. Moreover, some have considered the possibility that negative and positive feelings associated with a single person might be relatively independent, meaning that one might feel both extreme attraction and extreme repulsion toward the same individual. 
In regards to the physical characteristics typically associated with either attraction or repulsion, researchers Clelland Ford and Frank Beach, in the 1950s, made pioneering discoveries in this area.  By analyzing cross-cultural variations in values of perceptions of beauty, Ford and Beach were able to discern universal cues that point towards an evolutionary theory of physical attractiveness. As determined by their research, signs of youth, such as clear and smooth skin, signs of health, such as absence of sores and lesions, cleanliness, and freedom from disease are universally regarded as sexually attractive. In contrast, physical indicators such as poor complexion, pimples, ringworm, facial disfigurement, and filthiness are considered sexually repulsive.
Among the Trobriand Islanders in northwestern Melanesia, for example, anthropologist Bronislaw Malinowski reports that “sores, ulcers, and skin eruptions are naturally held to be specially repulsive from the viewpoint of erotic contact.”  Indicators, for the islanders, held to be especially attractive, from the view point of erotic contact, in contrast, are health, strong growth of hair, sound teeth, smooth skin, bright eyes, and full and well-shaped lips. Likewise, breast size and shape are equally held to have a certain attractive allure about them from the male perspective. Conversely, we might also reason, as based on the previous examples, that certain breast shapes and sizes will have a repulsive nature about them.
In this direction, it is commonly assumed that men will always be attracted to a pair of breasts. This, however, is a naive assumption. Common rating scales used to test for this are the 1-7 Likert scale, the 1-10 Hot-or-Not.com attractiveness scale. Moreover, at certain sites, such as RateMyBreasts.com or BabeRating.com, one can rate specific parts of a person such as their face, butt, chest, attitude, etc., These types of scales, however, fail to account for negative values of repulsion. Thus, herein, we will utilize the bi-dimensional 30-point attraction-to-repulsion (A/P) scale. That is, in this study 10 college-aged men were asked rate eight before-and-after photos of four women, aged 19-23, who had recently underwent breast implant surgery. Men were instructed to rate the photos using a scale of -30 (extremely repulsive) to 0 (ambivalent) to +30 (very attractive). These photos are shown below:
The results of this study, ranked in descending order from “most attractive” to “most repulsive”, are shown below. The attraction-to-repulsion rating scores (A/P Score) of the ten men were averaged together to obtain a mean value for the perceived level of either attraction or repulsion mediated by the visual sensory effect of these eight photos. The photo shown first was voted the most visually attractive and the last photo shown at the bottom of the list was voted most visually repulsive:
 Gottman, John. (1994). Why Marriages Succeed or Fail – and How You Can Make Yours Last. New York: Fireside.
 Berscheid, E. & Walster, E.H. (1969). Interpersonal Attraction. New York: Addison-Wesley Publishing Company, Inc.
 Small, Meredith F. (1995). What’s Love Got to Do with It? – the Evolution of Human Mating. New York: Anchor Books.
 Anderson, J. L. (1988). “Breasts, hips and buttocks revisited.” Ethol. and Sociobio. 9: 319-24.
 Symons, D. (1989). “Psychology of human mate preferences.” Behavioral and Brain Scineces, 12, 34-35.
 Buss, D.M. (1994). The Evolution of Desire – Strategies of Human Mating. New York Basic Books.
 Morris, D. (1977). The Human Sexes – A Natural History of Man and Women. New York: St. Martin’s Press.
 Ford, C.S. & Beach, F.A. (1951). Patterns of Sexual Behavior. New York: Harper & Row.
 Rhodes, R. & Zebrowitz, L.A. (2002). Facial Attractiveness - Evolutionary, Cognitive, and Social Perspectives. London: Ablex.
 Malinowski, B. (1929). The Sexual Life of the Savages in North-Western Melanesia. London: Routledge.
 Allan, N. & Fishel, D. (1979). Singles Bars. In N. Allan (Ed.), Urban life styles (pp. 128-79). Dubuque, IA: William C. Brown.
 Etcoff, N. (1999). Survival of the Prettiest – the Science of Beauty. New York: Anchor Books.
 Moller, A.P. (1992). "Tail Length and Symmetry: Female Swallow Preference for Symmetrical Male Sexual Ornaments.” Nature, 357, 238-39.
 Journal for Sex Research, Vol. 24, pp. 177-83.
In general, total interpersonal attractiveness can be divided into two bonding categories, i.e. neurological attractiveness attributes, such as personality, occupation, intelligence, etc., and physical attractiveness attributes, such as health, size, symmetry, complexion, etc. This study was concerned specifically with female breast visual appeal, with focus on size, averageness, and symmetry. The results of this study found that the ‘before’ photos had an average A-to-R value of -6.28, with a range of 2.8 to -15.4. Conversely, the ‘after’ photographs had an average A-to-R value of 21.0, with a range of 17.3 to 24.9.
As to methodology, this study was not as rigorous as strict scientific protocol demands. Due to the fact that the eight photos were shown to survey participants in bulk, i.e. all at once, there, of course, were “associative” factors that influenced the results. Second, because these photos were before and after pictures, further inconsistencies are to be expected as compared to if the photos were of eight different women. Third, skin tone should have been uniform in the ideal study, so as to isolate this as a negligible determinate. Lastly, small sample size, of course, limits the robustness the study. Nevertheless, we have significantly shown that “repulsion” is a strong determinate or factor involved in the dynamic process inter-human bonding.
In other words, artificial enhancement of breast size, a physical accruement in human females, changes perceptual levels of attraction and repulsion, in regards to these traits, in human males. A related study done in 1992 by zoologist Anders Moller showed that female swallows show increased attraction towards mates that have had their tail feathers artificially lengthened.  In their natural state, male swallows have tail feathers that are about twenty percent longer than the tail feathers of the females. The males with the longest tails, generally, attract more mates than other males.
The "averaged" computer-generated woman shown here, with a 34B breast size, was voted to be more physically attractive than as compared to anyone of the photos of the women that went into the composite photograph. Thus, both averageness and symmetry are factors in human bonding. 
Similarly, according to Frederick’s of Hollywood, the average bra size they sold in 1996 was 34B but in 2004 stated that it was up to 36C. According to the Journal of Sex Research, 15% of women are A-cup, 44% are B-cup, 28% are C-cup, and 10% are D-cup.  To compound this issue, according to the theory of evolution, morphological form, structural, and developmental change is an inevitable consequence of species growth. Thus, for example, if we look towards futurist artistic depictions of females, such as in comic books or video games, we tend to see a marked trend towards larger breast sizes. In the popular video game Tomb Raider, for example, Lara Croft is a 36DD. In the Movie, as based on the video game, actress Angelina Jolie, who is herself a 36C, had to wear a padded bra to "fill" the role of the futuristic action figure:
In this direction, in 2004 the IoHT conducted a study involving 10 men and 8 before-and-after breast augmentation photographs, to determine levels of attraction and repulsion with respect to breast size, shape, symmetry, color, and overall visual appeal.  The essential purpose of this study was to determine if “repulsion” is a significant factor in mate selection. In general, interpersonal attractiveness can be divided into neurological attractiveness attributes, such as personality, occupation, intelligence, etc., and physical attractiveness attributes, such as size, symmetry, complexion, etc. Here, we will concern ourselves with only female breast visual appeal.
At the most basic level, a good-sized breast signals fertility; it shows that a female is reaching reproductive age.  Conversely, others suggest that males should be looking for symmetrical breasts, breasts with good nipples capable of prolonged nursing.  In addition, many point out that there is no clear relationship between nipples, breasts, their size or shape, and the ability to nurse an infant.  In general, breast visual characteristics give an outward indicator of internal reproductive potential.
When anthropologist Napoleon Chagon was asked which females are most sexually attractive to Yanomomo Indian men of the Amazon, he replied without hesitation, “Females who are moko dude.”  The word moko, when used with respect to fruit, means that the fruit is harvestable, and when used with respect to women, it means that the woman is fertile. Thus, moko dude, when referring to fruit, means that the fruit is perfectly ripe and when referring to women, means that she is postpubescent but has not yet born her first child. 
Just as with fruit, an outward indicator of “ripeness” in women is the shape and size of the breasts. The age of maximum fecundity in the human female, i.e. the age at which she is most likely to be successful at bringing her fetus to term, is age 22 at which time breasts will be in their most pert shape.  There do, however, exist cultural differences. Men in many cultures prefer large, firm breasts, but a few, such as the Azande of Eastern Sudan and the Ganda of Uganda, men view long, pendulous breasts as more attractive. 
Recent research has shown that two quantities: averageness and symmetry are two major driving forces in mate selection. In scorpion flies and swallows, for example, males tend to prefer to mate with symmetrical females and tend to avoid those that show asymmetries.  Averageness is also highly sought after because average shapes are morphological indicators that the genetic structural components of an individual are within the “stable” range of traits for that population. According to English naturalist Charles Darwin, as based on fossil records, deviations from the norm, i.e. rarity, is a precursor to extinction.
Thus, in nature, average proportions often signal good health and good design. Measures of birds killed during storms find a high number with usually long or short wings. Survivors of the storm have average wingspans that give them the best liftoff and control of flight. Human babies who are born larger or smaller than average, which is about eight pounds, are less likely to survive.  The equation that averageness equals healthiness is such a predominate factor in the mating world that one physiologist, Johan Koeslag, calls this effect “koinophilia” meaning love for averageness. The following photo, for example, is a highly attractive photo, which shows an "averaged" morph of photographs of 70 random college-aged women:
“She often tended to say things that were scatterbrained and she had a nervous giggle. Her talk and her erratic laughter seemed quite secondary in the singles bars, as most men who talked to her were preoccupied with her chest and the way she displayed her chest by twisting and turning. Some men commented to us that they hardly heard what this woman said—or for that matter, even cared what she said. Such men seemed to prefer to look at this woman’s chest than to listen to her.”
In general, with respect to courting scenarios and interpersonal relationship interactions, more pressure is put on a female’s physical appearance whereas, with males, more pressure is put on financial prospects.  Thus, a woman with repulsive physical characteristics as well as a man with repulsive financial characteristics will have an innate evolutionary tendency or necessity to develop “attractive” characteristics in other areas, such as humor, personality, character, intelligence, etc., if they are to bond to either other people or society in a stable manner.
The evolutionary molding tendencies of these physical and neurological trait development process, such as the evolution and selection of larger breasts in women, is by no means a random process. In the words of science writer Matt Ridley, men and women mold each other:
Thus, as generations of men have wanted voluptuous women and generations of women have wanted alpha males, selection pressures have given us what we have desired. 
To determine these results, Moller performed cosmetic surgery on male swallows by snipping and gluing tail feathers onto the birds to make their tail feathers shorter, longer, symmetrical, and asymmetrical. Moller found females cared about both size and symmetry: females were attracted to greater size, however, long but asymmetrical tails were not as popular as the males with long symmetrical tails. This shows that changes in perceptual levels of attraction and repulsion, related to before-and-after cosmetic surgery modifications, is not alone an anthropomorphic tendency.
Knowing that a 5:1 ratio of attraction-to-repulsion functions in stable relationships, it is strikingly obvious that “repulsion factors", i.e. negative visual or neurological components of a person’s package are more powerful and significant in determining the stability of a human bond than are "attractive factors". That is, for every one component of a person's package that one does not like about someone there has to be five complementary components about that person that are likeable. This may explain, in a very stereotypically sense, why women with immature, small, petit, over-sized, or irregular breasts, may tend to have a more outgoing, warm, charismatic, or intelligent type of personality or character.
In singles bars, for example, physical accruements, for women especially, can serve as strong attractors. In bars, dance clubs, and other types of human mating grounds, psychology and anthropology researchers often secretly study human courting and mating behaviors incognito, while jotting notes from afar. In one study of courting behaviors in Dubuque Iowa bars, researchers reported that women “often walked around the room, standing tall, protruding their chests, holding in their stomachs, stroking their own arms or hair—they seem to exhibit themselves on public display.”  In many cases, according to these researchers, a women’s appearance is so effective that it preempts all other male thoughts. In one case, researchers described one woman who was thin, attractive, and large-breasted:
Tail length enhancement cosmetic surgery in swallows increases mate attractiveness
Thus, both "averageness" and "symmetry" are factors in sexual selection, but, in addition, subtle trends in evolutionary selective tendencies play a role as well.
Lara Croft (36DD): Tomb Raider
The following 2004 study (shown below), on the nature of the male-perspective of visual attraction and repulsion in respect to female breasts, was referenced in chapter six, Attraction and Repulsion (page-157), in the 2007 textbook Human Chemistry (Volume One), in connection to the photonic nature of attraction and repulsion in the structure and dynamics of the human chemical bond (A≡B) between "human molecules" (people):