Rob, just in case any doubt remains about where I'm coming from, I agree wholeheartedly with the following two statements:
"Supposing is good, but finding out is better." -- Mark Twain
"One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike -- and yet it is the most precious thing we have." -- Albert Einstein
You may of course accept or decline to accept anything I cast in your path. But at least consider the following, from ANATOMY OF LOVE: THE NATURAL HISTORY OF MONOGAMY, ADULTERY, AND DIVORCE, by Helen E. Fisher, Ph.D., published by W.W. Norton and Company (1992). This should command your attention: it's about sex! 
This violent emotional disturbance that we call infatuation (or attraction) may begin with a small molecule called phenylethylamine, or PEA. Known as the excitant amine, PEA is a substance in the brain that causes feelings of elation, exhilaration, and euphoria. But to understand exactly how PEA might contribute to attraction, you need to know a few things about the inside of your head.
The human brain is about the size of a grapefruit, weighing approximately three pounds, with an average volume of about 1,400 cubic centimeters....
In the 1970s neuroscientist Paul MacLean postulated that the brain is divided into three general sections. Actually, it is a good deal more complex than this, but MacLean's perspective is still useful as an overview. The most primitive section surrounds the final bulb at the end of the spinal cord. This area, which deserves its reputation as the "reptilian brain," governs instinctual behaviors such as aggression, territoriality, ritual, and the establishment of social heirarchies. We probably use this area of the brain in courtship when we "instinctively" strut, preen, and flirt.
Above and surrounding the reptilian brain is a group of structures in the middle of the head known collectively as the limbic system.... these structures govern the basic emotions -- fear, rage, joy, sadness, disgust, love, and hate. So when you are ovecome with happiness, paralyzed with firght, infuriated, revolted, or despondent, it is portions of the limbic system that are producing electrical and chimical disturbances. The storm of infatuation almost certainly has its physical origin here.
Overlaying the limbic system ... is the cortex, a gray, convoluted rind of spongy matter that lies directly below the skull. The cortex processes basic functions like sight, hearing, speech, and mathematical and musical abilities. Most important, the cortex integrates your emotions with your thoughts. It is this section of the brain that thinks about "him" or "her."
Here, then, is how PEA (and probably other neurochemicals, such as norepinephrine and dopamine) may play a role. Within and connecting the three basic parts of the brain are neurons, or nerve cells; there are at least one hundred billion of them. Impulses travel through one neuron and jump across a gap -- a synapse -- to the next nerve cell. This way they gambol along the neuronal highways of the mind.
PEA lies at the end of some nerve cells and helps the impulse jump from one neuron to the next. Equally important, PEA is a natural amphetamine; it revs up the brain. So psychiatrist Michael Liebowitz of the New York State Psychiatric Institute speculates that we feel infatuation when neurons in the limbic system, our emotional core, become saturated or sensitized by PEA and/or other brain chemicals -- and stimulate the brain.
No wonder lovers can stay awake all night talking and caressing. No wonder they become so absentminded, so giddy, so optimistic, so gregarious, so full of life. Naturally occurring amphetamines have pooled in the emotional centers of their brains; they are high on natural "speed."
...
With time, however, the brain can no longer tolerate this continually revved-up state. The nerve endings become either immune or exhausted, and exhilaration wanes. Some people sustain that smitten feeling for only weeks or months. Those who have a barrier to the relationship, like a marriage to a third party, can sometimes maintain elation over their beloved for several years. But most partners who see each other regularly feel the euphoria of attraction for some two to three years.
Then, as the excitement and novelty subside, the brain kicks in new chemicals, the endorphins, natural morphine-like substances that calm the mind. And as the endorphins surge along the brain's primeval pathways, Liebowitz maintains, they usher in the second stage of love -- attachment -- with its sensations of security and peace.
So infatuation and attachment have physiological components, and these emotions are common to humankind. Moreover, Liebowitz has proposed that these two distinctly different chemical systems in the brain evolved in the human animal for a simple reason: "For primitive man two aspects of relating to the opposite sex were important for survival as a species. The first was to have males and females become attracted to each other for long enough to have sex and reproduce. The second was for the males to become strongly attached to the females so that they stayed around while the females were raising their young and helped to gather food, find shelter, fight off marauders and teach the kids certain skills."
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What follows next, from WOMAN: AN INTIMATE GEOGRAPHY, by Natalie Angier, published by Houghton Miffin (1999), is for rufusTfirefly, who mentioned boobies. It's from the chapter about breasts. 
We live life vertiginously, attending to the round. Who knows why. It may have all started with the face. The first thing that a newborn pays visual attention to is not the breast, which the infant cannot adjust its focus to see from its ringside position, but the mother's face. Human faces are round, much rounder than those of other adult apes. The white of the human eye, which is absent in our simian cousins, serves to emphasize the roundness of the iris. When we smile, our cheeks become round, and the uplifted corner of the eyebrows create an image of a circle within a circle. Only humans universally interpret the smile as a friendly gesture. Among most primates, a smile is a grimace, an expression of threat or fear.
...
The breast is the body's most transparent way of paying homage to the circle. Over the centuries, the human breast has been compared to all the round things we know and love -- to apples, melons, suns, moons, cherries, faces, eyes, Orient pearls, globes, mandalas, worlds within worlds. Yet to focus exclusively on the breast is to neglect the other ways in which the human body commemorates and resonates with roundness. The buttocks, of course, are round and conspicuous. Our long human necks curve into our shoulders, a parabola of grace when seen from behind. Our muscles too assume a species-specific roundness and prominence. Other animals become extremely, densely muscular without forming the projecting curves seen on human athletes. Many creatures can outrun us, but none have our distinctive calf muscles, which, like the buttocks, are curved on men and women alike. The biceps of the arms can look breastlike. So too can the deltoids, the muscles of the shoulders. Highly developed chest muscles give the impression of cleavaged breasts. The curvaceous sensuality of the muscular male was not lost on the Greeks, nor on Michelangelo, nor on the photographer Bruce Weber, who in his pictures for Calvin Klein underwear gave us a nude male chest as vociferous as the conventional female cleavage shot. Dancers of both sexes, who have radiant, muscular bodies that are as if drawn with spirographs, emphasize and consecrate the curve through movement. To defy the choreographed curve is to renounce, mock, or affront the pretty.
...
To say that all breasts are pretty is like saying that all faces are pretty: it's true but false. Yes, we all have our winsome components, and we are genotypically and anatomically unique and uniqueness has its merit. At the same time, we know beauty when we see it. Beauty is a despot, but so what? Our mistake is in attributing grander meaning to a comely profile than it already has. High cheekbones, a high butt, and a high bosom are nice, but none should be viewed as the sine qua non of womanliness. If breasts had something important to say, they would be much less variable and whimsical than they are. They would be like mammary glands, a teaspoon per breast per woman. If breasts could talk, they would probably tell jokes -- every light-bulb joke in the book.
***
Dang, we still haven't got around ghosts, UFOs, or Nessie, have we?
