That is, unless you counted bacon. Bacon wasn't really pork. And the harder and crisper the bacon, the less pork it was. I think I was in high school when it finally dawned on me that those tasty, curly, carbonized strips had once been attached to an actual pig. Not that I cared. By then I had long suspected that my family's private version of Jewish dietary laws—no pork, except for overcooked bacon—had less to do with keeping God's commandments than with finding a way to combine old habits with the desire to raise healthy children. The then-prevalent idea that kids needed to start the day with a calorific, protein-rich breakfast that often included bacon seemed to trump whatever the Old Testament said about cloven hooves or chewing cud or the pure and the impure.

Bacon was just the beginning for me. It was a college boyfriend who introduced me to the glories of pork roast: oh, the crackly skin, the sweet flesh, the sheer carnal pleasure to be had for (in those days) a ridiculously low price! Thus began a romance that outlasted, by decades, my interest in the guy who led me down the garden path to the pigpen. By this point I've come to feel that hardly anything compares to pork, and I have to wonder why Judaism, Islam, and so many other religions and religious sects consider such a delicious thing so profane. A friend once told me that if you reduce the joys of pork to its essentials—crispy, fatty, juicy, salty—it explains why duck has sometimes been referred to as "Jewish pork." In which case, is duck also Muslim pork? Is chicken fried steak Seventh-Day Adventist pork? And do members of religions and castes that forbid meat altogether think of battered, fried eggplant as Brahmin pork?

Various theories have been put forward to explain the multicultural taboo against pork consumption. For a while, it was thought that the avoidance of pork reflected a fear of pigs as vectors of disease, a nervousness hardly assuaged by even the most casual observation of their diet (garbage), domestic preferences (mud), and occasional willingness (let me put this as delicately as possible) to ingest their own waste. My mother was so afraid of raw pork that she thought that unless we kept a close watch on the careless butcher who might accidentally grind the beef for our hamburgers in a machine that had just been used for making pork sausage, we would all be doomed to an agonizing death-by-tainted-hamburger. After all, my aunt knew someone who knew someone who knew someone who had died of trichinosis—a parasitic illness transmitted in undercooked pork. It's no wonder my bacon was always fried to a crisp.

But it has also been argued that many of the unsavory habits of pigs are also indulged in by chickens; as far as I know, only vegetarians won't eat poultry. And, though widely considered edible, goats are hardly famous for their tidiness or discriminating food choices. Besides, considering the limitations of scientific knowledge in ancient times, it would have been unlikely for the Hebrews and Egyptians to make the association between a pork dinner and an illness like trichinosis that might not manifest itself for days or even weeks. What should be clear by now is that, if you research the topic of food taboos in the library or on the Internet, you can rather quickly get sucked into a vortex of debate about meanings of the word impure that go well beyond the realm of health and science.

Anyone who has survived high school will be inclined to agree that food taboos have something to do with the seemingly hardwired and ineradicable human impulse to clump together in groups and invent arcane membership rules to exclude others. If we are what we eat, we are also what we don't eat, and others are what they do and don't eat, and so forth.

Food has always, obviously, been part of how we define ourselves. We tell ourselves that we're the kind of people who fill our supermarket carts with healthful fruits and vegetables and not with jumbo bags of Cheez Doodles and snacks sweetened with corn syrup. When you alter your diet, and especially when you break the laws that govern your diet, you change your identity. There's a moment in Philip Roth's novel The Plot Against America when the narrator's older brother Sandy comes home to New Jersey after having spent the summer on a farm in the South, where he's eaten pork chops, ham, and bacon for the first time. He's become a different guy. The fierceness and readiness with which we identify others with what they do or don't eat has led to all manner of bad behavior, ranging from racist slurs (the inexplicably resilient urban legend of Chinese restaurants' serving cat) to cruelty (mosques are said to have been washed down with pig blood in the course of the Indian partition in the 1940s) to torture (during the Spanish Inquisition, Jews were forced to choose between eating pork and being put to death).

Years ago, in Paris, I watched a series of nightly television documentaries in which, during each installment, a different farm couple in a different region of France was shown slaughtering a pig in the most humane way, using methods that evoked a proud history of animal husbandry and first-class sausage making. A few weeks later, a French friend told me that these picturesque, seemingly innocent documentaries had a political purpose. Their aim was to encourage French citizens to vote in the coming elections for the candidates who promised to defend their ancient peasant heritage against the incursion of immigrants, many of whom didn't eat pork.

One of the most intriguing and sensible theories of why some of us don't eat pork was argued in an essay called "The Abominable Pig" (Waveland, 1985) by the American anthropologist Marvin Harris. In his view, the proscription against pork is founded on a rational if intuitive grasp of ecology and of the food chain, as well as a gently Darwinian approach to the necessities of supply and demand. The trouble with the pig, says Harris, is that it is not a grass-eating ruminant, an important distinction that sends us back to see what the Bible says about the clean and the forbidden. According to Leviticus 11, "These are the creatures that you may eat from among all the land animals: any animal that has true hooves, and that chews the cud.... [T]he swine—although it has true hooves, with the hooves cleft through, it does not chew the cud: it is unclean for you."

Not chewing the cud is the deal breaker, Harris suggests. He traces this rationale to the fact that in the increasingly arid Middle East, the pig's fondness for shady, wooded spots as opposed to open grasslands became harder to satisfy, and its insistence on being fed grains meant that it was competing with its human owners for their daily bread. How much easier and more practical it was to coexist with (and eventually eat) cows, which, unlike pigs, gave you milk, butter, and cheese, which grazed on vegetable matter that humans weren't interested in consuming (like grass), and which had proclivities that were much more, well, tolerable—mooing instead of grunting, trotting after the herdsman instead of rolling in the mud—but not so lovable as those of domestic pets, the eating of which is also forbidden in most cultures.

Harris's ecological explanation sounds reasonable to me, and I'm touched by his confidence that our species will instinctively do the right thing for our survival. If he fails to convince me entirely, it may be because human behavior in more recent centuries has made me question his faith in our willingness to suppress our baser appetites (whether for delicious pig or yummy fossil fuels) for the benefit of other humans, flora, and fauna. And I can't help wondering how anyone can take such a functionalist approach to two of the most subjective and irrational subjects that exist—namely, food fears and religion. According to A Drizzle of Honey (St. Martin's Griffin, 1999), David M. Gitlitz and Linda Kay Davidson's book on the cooking habits of Jews who practiced their religion in secret during the Spanish Inquisition, a woman named Isabel de Rivera was brought before inquisitors in Mexico in the 17th century. Jews, she informed the court, can't eat pork "'because pigs are men who have been cursed by God, and until pigs rejoin the blessed, one cannot eat them.'"

Isabel de rivera's fantastical explanation may be as good as any. If food historians, anthropologists, and cultural theorists have failed to find the definitive source for the widespread interdiction against pork (and for other dietary taboos), it may be because religious food prohibitions, like religion itself, are mysteries based on mysteries. It's all about following the dictates of a faith that transcends science and logical explanation. It's about belief. These days, Jews who keep kosher and Muslims who observe the laws of halal may tell you that they have enough trust in the USDA to assume that they probably won't contract parasites from a slice of mortadella. And except for a few highly focused experts, rabbis, mullahs, and scholars, the faithful likely don't have much interest in hoof formation or the ingestion of grasses.

Though I know that it can't possibly be true, I've often wondered whether the proscription against pork might have something to do with how supremely delicious it is. What better way to test people's faith than to forbid them to eat something that sends out such mouthwatering aromas from their neighbor's kitchen or, more likely, their neighbor's desert encampment? Is it any wonder that the world's major religions, at least as far as I know, don't prevent their followers from eating any number of less universally popular items—for example, Brussels sprouts?

However they feel about Brussels sprouts or the aromas of cooking pork, most people who keep kosher or follow halal principles do so first and foremost in order to feel they are fulfilling the wishes of God or of Allah. Living according to these guidelines generates, for them, a kind of perpetual mindfulness, an awareness of how a close relationship with God can permeate and govern even the most humble aspects of daily life—the food shopping, the cooking, the eating. To break a dietary law is to transgress not only against the will of God but against a way of life that provides comfort, order, sustenance, and a sense of awe that for some of us is as necessary as respiration.

Certainly that's how it was in my family. My parents' old religion (their inherited Judaism) had to make room for their new religion (postwar American approaches to raising healthy children), and a compromise evolved. When I got old enough to interrogate my parents about their selective aversion to pork, even I knew better than to ask them why they had pretended that the bacon we ate practically every day might have come from some other animal completely. They never attempted to claim that it made any logical sense. It was a matter of faith, and it belonged to their religion—their own, private one.

Ironically, now that one of my own culture's prevailing beliefs—that is, the belief in a sensible, low-fat diet—has practically become a universal article of faith, my own family has come almost full circle back to a certain wariness about the health risks of pork. Quite honestly, I hadn't noticed how much of it my husband and I were consuming until our daughter-in-law remarked to our son, "Gee, your mom and dad eat an awful lot of bacon." And after my husband's cholesterol count confirmed the implications of her observation, we scaled back on the breakfast meat and the pasta alla carbonara. But however much we want to protect our hearts, we're just as reluctant to break them by giving up bacon completely.

I understand why others find comfort in faith. Though I sympathize with their longings and sometimes envy them the consolations that sustain them, I myself have fallen away from religion—my own and everyone else's. That's partly because of the intolerance with which the world's religions so often seem to encourage their members to treat members of other faiths. But if, however unlikely it seems, I ever find myself making one of those late-life turns toward God, one thing I can promise you is that this God will be a deity who wants me to feel exactly the way I feel when the marbled slice of pork floats to the top of the bowl of ramen or when the platter of sliced suckling pig arrives, crisp and moist, emitting curls of fragrance and steam that carry a message of bliss along the length of the table.