Dan Looker. Encyclopedia of Food and Culture. Editor: Solomon H Katz. Volume 3. New York: Charles Scribner’s Sons, 2003.

Human beings eat more meat of the pig than any other domesticated livestock on earth, even with pig being a food forbidden to more than one billion followers of Islam or Judaism. This lowly beast, whose intelligence and cleanliness has been underestimated for centuries, is a prolific animal that quickly converts a variety of feeds to a mild-flavored meat. One of the first domesticated animals, the pig appears in oriental and Greco-Roman mythology as well as in the Torah, the Bible, and the Qurʾan. Despite its utility as a source of food, leather, and pharmaceuticals, the word, pig, is an insult or gentle rebuke in many cultures. While the pig itself may not have grown more controversial, its modern, industrialized husbandry draws criticism from an array of opponents.

The Omnivorous Pig

The pig, Sus scrofa domestica, is a subspecies of Sus scrofa, the Eurasian wild boar. It is in the order of mammals, Artiodactyla, which means even-toed and hoofed. That order includes ruminant livestock such as cattle. Bacteria in the rumen help these animals digest cellulose in grasses. Sus scrofa is a member of the Family Suidae, or swine. These animals do not ruminate and cannot digest grasses. They are omnivores. In the wild, their diet is fungi, leaves, roots, bulbs, tubers, fruit, snails, earthworms, small vertebrates, eggs, and carrion. The Suidae family includes African bushpigs and African warthogs.

There are some three hundred breeds of domestic pigs. Most are endangered. In the United States, only eight breeds are widely used for commercial production: the Berkshire, Chester White, Hampshire, Duroc, Yorkshire, Landrace, Poland China, and Spots. The Meishan breed, developed in China two thousand years ago, was imported to the United States in 1989 for research and to add genetic diversity.

In common usage, most people make no distinction between a pig and swine, but the precise meaning of pig is “a young swine.” The experienced swine breeder Kelly Klober notes that “what really separates the pros from the tenderfeet is how the word ‘pig’ is used. To be country correct, it is the term for a very young pig. A hog is a swine that weighs over 120 pounds” (Klober, p. 24). A mature female swine is a sow. A mature male is a boar. Barrows are castrated male pigs raised for slaughter. Gilts are immature females. Both are sold as “market hogs” at five to seven months of age and at weights of between 220 to 260 pounds. Mature hogs can grow much larger. Boars have topped one ton.

Use of the meat of the pig, known as pork, is also not without controversy. Until the early twentieth century, the hog was bred for fat, or lard, just as much as for meat. Later in that century, the saturated fats found in many types of meat were targeted as contributors to coronary heart disease. Breeding and changes in the way hogs are fed has made modern swine 30 to 50 percent leaner than in 1950. At the beginning of the twentieth century, the lard-type hog, nicknamed “cob rollers,” was so fat that its stubby legs were barely visible.

Pushing the Chicken Fat Barrier

The leanest cuts of pork can approach the fat content of skinless chicken breast. According to U.S. Department of Agriculture (USDA) nutrition data cited by the National Pork Board, an industry group, a three-ounce roasted pork tenderloin has 4.1 grams of total fat, more than the 3.1 grams in a comparable portion of roasted, skinless chicken breast, but much less than the 9.3 grams in a chicken thigh.

Lean cuts of pork are also richer in some essential vitamins and minerals than other meats. Another USDA database lists broiled fresh pork as having .923 milligrams of thiamin, or vitamin B1, in a 100 gram serving (about 3.5 ounces). That amount is more than half of the recommended daily consumption of thiamin and ten times the amount of thiamin found in a comparable cut of beef and even more than the amount in chicken breast (0.070 mg). The body uses thiamin to metabolize carbohydrates, protein, and fat.

The Pig’s Fatty Underbelly

For all of modern pork’s improved qualities, the pig is still a source of less desirable calories. As much as two-thirds of each slaughtered hog is used for processed meats—hams, sausages, and bacon. These meat products can be much higher in fat and salt than the amounts considered healthy by the medical profession.

The Center for Science in the Public Interest in the United States characterizes bacon, hot dogs, and sausage, all of which can contain pork, as among the most unhealthy foods available, recommending that consumers buy bacon and sausage that has no more than 45 percent of its calories from fat and no more than 480 milligrams of sodium per serving. In a recent survey of products sold in grocery stores, typical pork bacon (which comes from a pig’s belly) had a whopping 9 percent of its calories in the form of fat. Only certain brands of turkey bacon were truly “low fat.” The pork bacon was lower than turkey bacon in sodium, however, with only 170 milligrams.

Lean or fat, the swine family is an old one, geologically and in the archeological records of early human agriculture and civilization. The swine family has inhabited the earth since about forty-five million years ago, when the horrific seven-foot-high entelodont roamed central Asia and North America. Like modern pigs, entelodonts had cloven hooves and were omnivores. Their scarred fossils show evidence of fierce battles. They had much smaller brains and may not have had the social herding characteristics of modern swine. They died out twenty-five million years ago and were succeeded by smaller direct ancestors of the wild boar and modern pig.

Older Than the Cow

The pig is one of the first domesticated animals: its remains in some archeological excavations have been found to date earlier than the bones of cattle. Agricultural settlements raised pigs in the Middle East at least nine to ten thousand years ago. In Jericho, one of the world’s most ancient cities, archeologists unearthed domesticated pig bones in soil layers predating 7000 B.C.E. Archeological excavations in the East Indies and Southeastern Asia show evidence of domesticated swine at about the same time. The East Asian pig arrived in China around 5000 B.C.E. Some of the first written recipes for pork are from China, where the pig has been an integral part of agriculture for thousands of years, feeding on garden waste and table scraps in pens next to farm huts. Recent archeological evidence suggests that Neolithic farmers rapidly spread agriculture, and pigs, along the Mediterranean shore of Europe before 5500 B.C.E.

The pig appears again in the writing and art of first recorded history. Pork was a popular food in early dynasties of Egypt. The ancient Greeks ate pigs. The Romans were masters of smoking and salting pork. From the time of medieval Europe through colonial North America, pigs were allowed to forage for acorns, nuts, and other foods in the forest in a semi-wild state. In the fall, they would be rounded up, slaughtered, butchered, and preserved by smoking, salting, and curing. In the United States, the pig was the most popular source of meat through the nineteenth century. The westward migration of American settlers into what would become the Corn Belt in America’s Midwestern states was the perfect marriage of an Old World livestock with the grain of native Americans. The diet of swine shifted ever more from woodland forage and scraps to corn. Not until the 1950s did beef surpass pork as the most popular meat in America. Increased beef consumption coincided with the rise of industrialized cattle feedlots and post-World War II affluence. With suburbanization came the popularity of backyard grilling of steaks and hamburgers.

Many of the breeds of swine raised in North America came from England, as their names, Hampshire, Yorkshire and Berkshire, suggest. Some of these English breeds are at least four hundred years old, according to both historical records and DNA studies.

Prolific and Efficient Meat Producers

The Spanish, too, brought hogs with them to the New World. The explorer, Hernando de Soto landed in what is now Tampa Bay, Florida, in 1539 with thirteen hogs. Three years later, the swine herd had grown to seven hundred.

This ability to multiply rapidly is a quality that endears the pig to some of the poorest farmers on earth as well as the most modern swine production complexes. A sow produces almost three litters of pigs a year, although 2.25 litters per year is more realistic on smaller, traditional farms. From each litter eight or more pigs usually survive. Sows on large commercial farms can produce nearly twenty-six pigs per year.

Not only are pigs prolific, they grow fast on modest amounts of feed. A pig easily gains a pound for every three to five pounds of feed it eats, reaching more than two hundred pounds in six months. In some intensive industrial swine farms, where pigs are confined in a small space with little to do but eat, feed efficiency has approached one pound of meat for every two pounds of feed—about the same as poultry. Pigs are much more efficient at converting grain to meat than cattle or sheep.

Until the late twentieth century, pigs were weaned from their sow from about thirty-five to fifty-six days after they were born. From a birth weight of about three pounds, they would reach a weaning weight of about forty to fifty pounds by fifty-six days. After a short period of receiving a rich “starter feed” of grains, milk products, and perhaps medication, the pigs were ready to sell to another farmer who specialized in “finishing,” or feeding hogs to market weights. Sometimes the farmer whose sows produced the pigs would keep the pigs and move them to another barn or pen to feed them to market weight in a method of production called “farrow to finish.” (Farrowing refers to the action of a sow giving birth.) Farrow-to-finish production was typical of small-and medium-size “family farms” in North America. On some farms, farrowing took place in small huts big enough for one sow, placed in a pasture of alfalfa or other digestible forage. After 1950, farrowing more commonly took place in specialized buildings or modified barns.

The farmers who specialized in farrowing would cross several breeds of swine in order to produce stronger, healthier pigs that grow faster. This benefit from cross-breeding was called hybrid vigor. Farmers who specialized in feeding pigs for slaughter began to separate them by sex, so that the males and females could be given different feeding rations tailored to the nutritional needs of each sex.

Commercial Complexity

In large commercial farms, swine production is even more complex, having moved beyond the traditional one-site or two-site production system. On these farms, pigs are weaned at much earlier ages, sometimes when only ten to fourteen days old. This technique, called medicated early weaning, was developed in Britain in the 1980s by veterinary medicine professor Tom Alexander at the University of Cambridge. Alexander discovered that very early weaning could prevent a sow from passing certain swine diseases to the next generation of piglets. Weaned pigs are moved to separate nursery buildings, at enough distance to lessen the chance of infection by wind-born disease agents. The pigs are usually held in the nursery for seven weeks. before they are moved to another set of buildings for the “finisher-production” stage, where they reach slaughter weights.

In large pig farms, pigs are kept in small groups that remain isolated from older pigs. By avoiding the mixing of pigs after they are weaned, the risk of spreading diseases is lowered. Each week, while one group of pigs is moved from the site where they were born to a nursery building, another group is moved from a nursery to a finishing building, and yet another is moved out of a finishing building to the slaughter plant. After each group is moved, the building is washed and disinfected. To make this system work like a well-oiled machine, the farm or hog producing company must have 12,000 to 24,000 sows. This system can produce more than 600,000 market hogs a year.

Industrialized Production Spreads across the Globe

This multisite system of production has existed along with the more traditional ones, in which farmers raised only a few hundred or a few thousand pigs for slaughter. But at the start of the new millennium, multisite production was rapidly taking over the industry. In Corn Belt hog-producing states, individual families that ran grain farms still fed hogs, but only in the second and third stages of multisite production. The families no longer owned the pigs. Instead, they raised them for large companies, much as local entrepreneurs run franchise outlets for fast-food chains. The pigs were owned, from birth through slaughter, by large companies, including packers. The parent animals in this system are complex proprietary mixtures of breeds owned by a handful of multinational companies. By the late 1990s, more than half of U.S. production was in some stage of this “vertical integration,” meaning that each step in hog raising is owned or controlled by one company. The multisite pig production system was becoming global, existing not only in the United States and Britain, but also in Canada, Mexico, Brazil, Chile, Spain, Germany, Poland, Italy, China, and France.

Many of these countries are also the top producers and consumers of pigs. China is the leader, producing 43.2 million metric tons of pork in 2002, more than half of the global production of 85.2 million tons. The European Union was a distant second, with 17.8 million tons. The United States ranked third, producing 8.7 million metric tons of pork. China’s livestock practices supply the main reason the world eats much more pork than other meats. Of the world annual beef production of about fifty million tons, China raises only 5.8 million tons of beef.

Pigs Led to Slaughter

Just as pig farming has changed, so has the slaughter of hogs and the curing of pork. Hogs are trucked to packing plants where they are unloaded, held in pens to fast, and then slaughtered, most commonly by stunning with a high-voltage electrical shock. Then the carcass is hung by the hind legs from an elevated conveyor line, bled, and cut apart. The treatment of hogs before slaughter is both an economic issue as well as one of humane treatment. If the animals are frightened and stressed for a long period of time, lactic acid builds up in the muscles, affecting meat quality. Some breeds of pigs are more susceptible to stress than others and can produce pale, watery fresh meat. The swine industry has dealt with the problem two ways. First, it has bred hogs to exclude lines that produce poor quality meat when stressed. Second, the packing industry is changing slaughter methods to treat hogs more humanely, which also reduces stress.

Colorado State University animal scientist Temple Grandin has devoted her life to making the last few minutes of cattle and hogs as pleasant as possible. As a result of her studies of how animals react to new environments, both farmers and slaughter plants are starting to move pigs through curved chutes onto trucks, and out of trucks into the packing plant to prevent pigs from witnessing what lies at the end of the line. Pigs are instinctively frightened when forced into a confined space. In Denmark, slaughter plants are experimenting with stunning hogs with carbon dioxide gas, which may be less stressful than electrical shock.

Refrigeration is the modern method of preserving pork, even for most ham and bacon, which is injected with brine, smoke flavoring, and, usually, sodium nitrite to give the meat a pink color and to protect against the growth of toxins responsible for botulism.

The Art of Curing and Cooking Pork

Traditional methods of air curing, which may date to pre-Roman times, are still used in China, Europe, and the American South. Hams are made by covering the meat, usually from the upper rear leg or hip but sometimes from the shoulder, with salt, sometimes sugar, and flavorings for several days in a cooler. The meat is then smoked at room temperatures in a smokehouse for about ten days and allowed to cure for at least six months. Before cooking, traditional air-cured hams should be soaked in cold water to remove excess salt.

Exactly why so much of the pig is cured and made into bacon and ham, while less beef and lamb is consumed as dried or smoked products may be a question for archeologists, not historians. One theory about the popularity of cured pork, offered by the National Pork Board, is that pork is a mild meat that, having less flavor than some meats, readily takes on added flavors.

Fresh pork faces another obstacle when compared to flavorful cured meats. As it became leaner in the late twentieth century, the potential to make fresh pork less palatable by overcooking increased. With less fat in the meat, overcooking can make pork taste very dry. The habit of overcooking stems from consumer fears that rare pork risks exposure to the parasite that causes trichinosis. The parasite has been virtually eliminated from pork in most developed countries. To be safe, food experts recommend cooking pork until internal meat temperatures reach 170 degrees Fahrenheit, or piercing to the center of a cut of cooked pork. If the juices run clear, the meat is done, and no further cooking is needed.

Fighting the Flavor Drought

Dry pork is just one factor causing a growing reaction against raising pigs in the industrial system. As North Americans and Europeans consume more natural and organic vegetables, grains, and dairy products, a market is developing for natural and organic meats raised on smaller farms, sometimes with methods that animal welfare organizations consider more humane.

In the United States, one company, Niman Ranch of San Francisco, California, hires farmers to raise pigs without antibiotics or growth hormones for sale to natural foods stores and upscale restaurants. These farmers raise pigs in pastures or on straw bedding in barns and sheds and periodically submit samples of meat to a taste panel to make sure that it is not too lean to be palatable. They use swine breeds that are not quite as lean as the crossbred hogs in large multisite hog businesses. After tasting this type of pork, New York Times food writer Marian Burros reviewed it as “so delicious it needed no seasoning beyond salt and pepper … [The] meat was superior heirloom pork, suffused with a bright clean flavor, with none of the unpleasant aftertaste that pork often has” (September 1999).

Dry pork is less of a problem in China, where much of the pig meat consumed in that country still comes from small farms and traditional breeds that are not as lean as those from Europe. The western provinces of China, known for spicy Szechwan dishes, also produce a type of ham, Yunnan or Xuanwei ham, that is exported to Southeast Asia and Europe. Mu Shu pork, consumed in the northern provinces near Beijing, is a dish that is popular in the United States as well. This rural Chinese dish is a mixture of sautéed pork and diced vegetables that is wrapped in small, steamed pancakes and dipped in a sauce. Unlike in the West, where pork is eaten by itself, in China most recipes use it sparingly, cut into small pieces and mixed with other ingredients. Blending flavors of many foods, an important principle of Chinese cuisine, has stretched supplies of pork and other meats in times of scarcity. The preciousness of pork may also be why no part of a pig is wasted in China. Even the head of the pig continues to be served by some pushcart vendors and urban restaurants.

Fear and Loathing of Pigs

As beloved as pork is in many cultures, the pig is despised in the traditions of others. Many theories exist to explain why Islam and Judaism consider the meat of pigs unclean. To some followers of these faiths, the abhorrent nature of pigs is obvious. The animals often wallow in mud and look dirty. But pigs, unable to sweat, wallow in mud as an efficient way to stay cool. Nevertheless, their breeding conditions may have created a social stigma. Animal scientists M. Eugene Ensminger and R. O. Parker point out that because “close confinement was invariably accompanied by the foul odors of the pig sty … early keepers of swine were often regarded with contempt” (Ensminger and Parker, p. 1 ).

Anthropologist Marvin argues that the pig’s downfall in the Middle East was economic. Pigs are costly to raise in the climate of the Middle East. They are more difficult to herd than the sheep and goats favored by the desert nomads who quickly adopted Islam. And there is evidence that over the past ten thousand years, the environment in the Middle East grew less hospitable for animals originally adapted to foraging in forests.

Harris contends that for Jews, “the food laws of Leviticus were mostly codifications of traditional food prejudices and avoidances” (Harris, 1985, p. 79). A book of the Torah, Leviticus was written in 450 B.C.E., long after swine herding and consumption had lost prestige in many other ancient near eastern cultures as well as in ancient Israel. He finds even more support for his theory in China, where pork-disdaining Islam failed to penetrate far. There, the pig complemented an agrarian ecology, eating stems, leaves and scraps from many vegetable crops, and in turn, being eaten.

Archeological digs in the Middle East give evidence that the pig was once worshipped as well as eaten. In early stages of Phoenician, Egyptian, and Babylonian civilizations, people freely ate pork. But as those civilizations matured, pork fell from favor. When the Greek historian Herodotus visited Egypt before 430 B.C.E., he saw that “the pig is regarded among them as an unclean animal so much so that if a man in passing accidentally touches a pig, he instantly hurries into the river and plunges in with all his clothes on” (quoted in Harris, 1985, p. 83).

The anthropologist Carlton Coon attributes the demise of pigs in this region of the world to deforestation and population increases. At the beginning of the Neolithic period, pigs could root in oak and beech forests. As human population density increased, Coon argues, the forests were cleared to make room for more farms, especially olive groves, and in times of famine and scarcity, pigs competed with humans for life-giving grain.

Pigs Provide More than Meat

In the future, the economic relationship to cultural and religious taboos may be tested if pigs become more than a source of meat and go on to save more lives. Besides providing pigskin leather and byproducts with industrial uses, pigs are already a source of pharmaceuticals, such as insulin. Since 1971, pig heart valves have been used to replace damaged human heart valves. Pig valves are treated and contain no living cells, preventing rejection by the human immune system. Soon, genetic manipulation may allow transplants of whole, living organs from pigs to humans. Pigs offer an advantage over other animalsby closely matching those of humans.

Many scientific barriers remain, but in early 2002 two rival biotechnology companies announced a major step toward xenotransplantation (the transplanting of animal organs into humans). Both had cloned pigs that are missing a gene that causes an immune reaction in humans. The offending gene sets off production of an enzyme that makes a sugar that human bodies recognize as foreign. Pig organ transplants without the gene may be less likely to be rejected.

Even in cultures that do not view pigs as unclean, xenotransplantation has vocal opponents, including animal rights activists and others who worry that this technology may introduce new viruses from pigs to humans.

The Pig in Myth

It remains to be seen whether pigs will physically become parts of humans. Symbolically, they have been transplanted into human culture for centuries, in medieval Europe, modern China, and ancient Mesopotamia. Pigs first symbolized deities, and later, human weaknesses and strengths.

In China, the pig is one of twelve animals symbolizing a year in a twelve-year lunar calendar. According to Chinese mythology, all animals were invited to race for this honor. A year was assigned to the first twelve winners, as each one finished. The pig came in twelfth. Just as westerners who believe in astrology tie personality traits to signs of the Zodiac, the Chinese attribute personality traits to the year in which they were born. Those born in the Year of the Pig (also called Year of the Boar) are said to be easygoing, sincere, tolerant, and honest. They are also considered naïve. Naïveté was linked to pigs in Homer’s Odyssey, when Ulysses’ men were turned to pigs by the sorceress Circe. While the men themselves were naïve, their behavior even before their conversion was almost piglike. They were attracted by Circe’s sweet voice and lulled to complacency by her rich meal. Homer seems to use this tale to impart a sensuality to pigs, as well as a pig-likeness to the mariners. The pig was sacred to Aphrodite and an important image in Celtic mythology.

A vision of a sacred white sow was part of the legend of the founding of Rome. In Christian Europe, the sensuality of pigs came to take on a harder edge, an association with gluttony, perhaps because Jesus is depicted as casting demons into swine. The strong personality of the squealing, ever-present pig became a convenient device for the writers and fable makers of Europe in the eleventh through thirteenth centuries. Moralized fables called bestiaries made use of pigs to symbolize the Seven Deadly Sins, not just gluttony, but also pride, covetousness, lust, envy, anger, and sloth.

Pigs are recognized as intelligent, exhibiting a range of emotions and behaviors in real life just as in fables and mythology. For centuries, farmers have found herding and catching pigs difficult. This intelligence makes pigs a priority for animal rights organizations that challenge the methods of confining pigs in intensive industrial production, in which pigs are kept on concrete floors with slats that allow for the collection and flushing of manure into earthen lagoons or metal holding tanks.

Modern confinement appears clean compared to hogs wallowing in outdoor pens. The use of metal crates to restrict sow movement is humane, say the system’s defenders, because it prevents newborn pigs from accidentally being crushed by a heavy sow. The U.S. National Pork Board’s position on animal welfare is that “because the welfare of their animals directly affects their livelihood, pork producers work to ensure their animals are treated humanely. Anything else would be self-defeating.” Some farmers are, in fact, beginning to revise their methods.

Attempts to Treat Pigs More Humanely

At the urging of farmers in Sweden, that nation in 1986 banned the routine use of antibiotics in raising animals for food. In 1988, it required that all animals used for food be allowed to behave naturally. Small metal stalls that restrict the movement of sows about to give birth were banned. Minimum space requirements for sows and boars were established for hog buildings. If pigs were housed inside, straw bedding was required, to absorb manure, to keep pigs clean and dry, and to give pigs a place to root, a natural behavior. In the United States, the Animal Welfare Institute, founded in 1951, has worked with farmers to set up voluntary use of Swedish pig-raising methods.

Straw bedding must periodically be moved onto farm fields to keep pig buildings clean. This requires labor that larger intensive farms may not have. Large farms flush manure with water into lagoons or tanks. That manure is also spread onto farmland as fertilizer. But critics charge that current environmental standards in the United States do not require the manure to be spread over a wide enough area and allow it to eventually build up excessive amounts of nutrients in soils that can wash into streams or contaminate groundwater. Spills of manure have already caused fish kills and stream pollution in Midwestern states. In 1999 a large hog-producing company in Missouri, Premium Standard Farms, agreed to pay $25 million to settle a lawsuit accusing it of violating the state’s Clean Water Act.

Clearing the Air?

Untreated pig manure stored in open-air lagoons or tanks just plain stinks to neighbors and rural residents. In part because of complaints from rural voters, the Iowa legislature passed a law in 2002 that will require manure from confined hogs to be spread over more land. In a state with five times as many pigs as people (nearly fifteen million), the Department of Natural Resources is also developing a scoring system that considers community and environmental needs before the department approves construction of any more large hog buildings. Yet the law gives local governments no control of hog farm growth, critics say.

Adding low levels of antibiotics to pig feed may be the most serious environmental challenge from largescale confined livestock. Feeding antibiotics has fostered antibiotic-resistant bacteria in livestock, including pigs. These antibiotic-resistant bacteria can be transferred from animals to people. Resistance genes may also transfer from one bacteria type to another more dangerous one such as salmonella.

In 1999, the Center for Science in the Public Interest, the Union of Concerned Scientists and several environmental groups petitioned the U.S. Food and Drug Administration to rescind the approval of agricultural use of antibiotics when their use endangers human health. Other groups supporting that view include the World Health Organization, the Centers for Disease Control and Prevention, and the American Public Health Association. Some of these antibiotics have been banned from feed in Europe.

Hygiene, humane farming, and health benefits and threats are among the many controversies surrounding the controversial pig, an animal that is likely to continue to feed the minds and stomachs of billions of humans as it has already for thousands of years.