Have you ever noticed that we are unable to determine either the identity or even, beyond a certain point, the attractiveness of a human face if it's presented to us upside-down? Give anybody a photo where the subject is inverted, and they generally have to turn it over to make any sense of it. I'm always reminded of this fact of our wiring when Susan reads a magazine across from me at the kitchen counter. In rare cases I can pick out some give-away feature--Tom Cruise's misaligned smile, for example (though maybe it's the nutty smell of self-immolation gives him away)--but most of the time I guess wrong, or I have to make a pointed effort to try to remember, by way of reference to a right-side-up mental image of my choices, exactly how Angelina Jolie differs from Katie Holmes (I mean, beyond Angelina not being a homunculus). We are said to have a certain mental component specifically for recognizing faces, presumably since so much of the social tendencies which define our species involves our ability to recognize and read other people. This seems ready proof that something of the sort is at work.
It's always been obvious to me that what we find beautiful is absolutely arbitrary. The assessments of physical attractiveness we make follow a very species-specific (and culture-specific) yardstick; no person goes all fluttery about an orangutan or a lemur (well, Richard Gere had that gerbil thing). As a confirmed breast man, I've long been baffled at how we can find a feature or a shape mesmerizing; but I'm here to tell you it's a fact, something of which I am reminded a thousand times a day (or should I be an ass and say five hundred times a day. Twice). Contrary to our Star Trek training, an alien from another star system would almost certainly not look humanoid, and would find human beings to be hideous, monstrous. And yet we humans all swoon at the sight of a beautiful person.
And love. We may come to love a horse or our dog, but clearly the love we feel for non-human animals is something distinct from the attractions we feel toward select others of our species. As is true for cows and manatees and hummingbirds and praying mantises. And all this is programmed into our genes, which, if one spends some time thinking about it, rather upends our whole visceral sense of reality. It's a subject that leads to some cool places.
I've probably written before about journalist Robert Wright's 1994 book The Moral Animal, a wonderful survey and summary of the field of evolutionary psychology. If I may be allowed a layman's attempt at a definition, the field of evolutionary psychology extends the basic mechanisms of Darwinian natural selection--mechanisms which most people understand affect, say, the length and shape of a bird's bill, or the coloring of a desert reptile--into the realm of human behavior. This is not a sphere where evolution was originally thought to have held much sway, but evolutionary psychology starts with the premise that everything about us should be explicable in terms of its role in getting our genes into the next generation. That is the purpose behind our very existence; it is the basest motivation of the genes that built us. (This is a subject most eloquently explored in several brilliant books by Richard Dawkins: Unweaving the Rainbow, Climbing Mount Improbable, The Blind Watchmaker, and The Selfish Gene, among others.)
In the course of Robert Wright's book, such things as the differences between male fantasies and female fantasies, the function of pouting, petty theft, or female emotional wiles and male unwillingness to ask for directions--these and many other things all fall under the evolutionary microscope. The results are absolutely eye-opening, but also disorienting (I remember one review at the time the book came out cautioned that it was "not for the faint of heart" as concerns one's world view). Where we began by surveying a landscape of quirks and endearingly odd behavioral mannerisms, we end up seeing each thing as playing a role in biology's huge machine. Like a Bach fugue, nothing is there by chance. It's like turning a klieg light on the concepts of intuition and free will.
The stereotyped sex roles of men and women make for an instructive example. (Anticipating his audience's discomfort, Wright makes a point of saying that what we're designed to do does not imply a moral imperative to every behavior; we're perfectly within our rights to determine that it's in our interest to control and controvert our instincts to whatever degree.) Though there are a couple of exceptions, it's very nearly a rule in the animal kingdom that the females of every species are sexually coy, and the males are sexually assertive, promiscuous even. How these characteristics play out in different species is itself a fascinating thing, but for our purposes we can contemplate the fact of it in human culture. But why should it be so?
Female, in this context (I confess I had never actually thought about a definition for the terms male and female beyond anatomical markers) is defined as the sex with the larger genetic package--not the number of chromosomes, of course, but the size or "value" of the parcel in which the chromosomes are transmitted. A woman's egg is many times the size of a man's sperm, and is correspondingly many times as costly to the woman to produce. Well, this fact lies at the foundation of a huge complex of human behaviors, things of which we are all aware but we may not have connected the dots this way to explain them.
A woman produces basically an egg per month from her early-mid teens through her 50s or so--roughly 500 eggs (I understand that a woman is born with all her eggs, that she doesn't technically produce them monthly; but you get my point). Each one of these that comes to fruition puts her, reproductively speaking, out of commission for a year or more, and mandates, in the small print, a decade and a half of commitment from her. A man, by contrast, produces something like 20 million sperm in a single ejaculation. And for those who require a reminder, a man can ejaculate once or twice or thrice a day from his teens until into his eighties. It's an astronomical number.
So in the most basic sense, a woman's egg is a hugely precious thing to her and a man's individual sperm is well-nigh worthless to him. It is this difference in relative value that sets the stage for our divergent sexual tendencies. Think of these things acting upon humanity, say, 10,000 years ago; this is the environment in which our tendencies formed. Looked at from the perspective that the primary thing we're wired to do (after basic survival) is get our genes into the next generation, we can see that a man has an incentive to spread his seed at every opportunity, whereas a woman has every reason to be very selective of her sexual partner. A man's genes may "know" that a child fathered which he doesn't stick around to help raise has a much smaller chance of survival, but when the sperm are virtually free, why not jump at each opportunity? He can stick around and raise his nuclear family, and still benefit (from the gene's perspective) from a little hanky-panky on the side. Any kid that survives carries his genes on into posterity. Mission accomplished. So in light of that, it's not surprising that men are visual, and oriented toward the obvious markers of health and fertility: youth and symmetry and beauty.
A woman's situation is entirely different. She is biologically designed to provide care for her baby, even bodily producing its food. Unlike many species, human children are born utterly helpless, and they remain unable to look after themselves for a period of years. This is a challenge for the child, of course, but also for its prime caregiver. Babies are a lot of work. A woman's genes also "know" that a child is unlikely to survive if she is born without the protection and assistance of her father, but she can't just toss off another try. So her motivations should be different from a man's, and indeed her tendencies are quite opposite to his. The man wants to tap anything that will stand still for him, and the woman wants to give herself only to a very specific fellow; she wants some proof that the man will stick around at least long enough for the child to become basically self-sustaining (it's said that this is the source of the so-called "seven year itch"). Without this assistance--again, think 10,000 years ago--the mother's genes have little chance of propagating; a disaster from the point of view of an individual organism. So what does she fantasize about? The man who will brave hell and high water to save and protect her, who will fight off every threat and provide for her.
And, political correctness be damned, we see these very things every single day of our lives. It's why men read Maxim and women read romance novels (when they're not studying law or chemistry or whatever). Men and women tell jokes about each other's inherent tendencies, and any fool can see a whole host of differences. But it's fascinating to me that these things can come down to identifiable physical, nay, biological features.