Mammals (Encyclopedia of Science)
More than 4,000 species of living mammals belong to the vertebrate class Mammalia. This diverse group of animals has certain common features: all have four legs, bodies covered by hair, a high and constant body temperature, a muscular diaphragm used in breathing, a lower jaw consisting of a single bone, and three bones in the middle ear. In addition, all female mammals have milk-producing glands. There are three living subclasses of mammals: the Monotremata (egg-laying mammals), the Marsupialia (pouched mammals), and the Placentalia (placental mammals).
Mammals range in size from bats, some of which weigh less than an ounce, to the blue whale, which weighs more than 200,000 pounds. Mammals are found in arctic climates, in hot deserts, and in every terrain in between. Marine mammals, such as whales and seals, spend most of their time in the ocean. Mammals are not as numerous and diverse as other classes of animals, such as birds or insects. Nonetheless, mammals have a tremendous impact on the environment, particularly because of the activities of one species of mammal: humans.
Species of mammals have developed a variety of adaptations in response to the different environments in which they live. Mammals in cold climates have insulating layers consisting of a thick coat of fur or a thick layer of fat...
(The entire section is 513 words.)
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Mammals (Encyclopedia of Food & Culture)
MAMMALS. Mammalsarm-blooded, milk-producing animalsave provided meat protein, milk protein, collagen, hides for leather and shelter, and bones and sinew for various tools since humans began to hunt. Mammals also have provided the power for transportation (still called horsepower) and for heavy lifting or pulling. They have often been regarded as companion animals. Indeed, the existence and progress of humanity have depended heavily on mammals. As human societies became more complex and some took up the settled practices of farming and animal husbandry, certain mammalian species were selected to provide sustainable supplies of meat protein. Bovine (cattle), porcine (swine), ovine (sheep), and caprine (goat) species became valued livestock. Domestic animals, whether raised for food, work, or companionship, were selectively bred by controlling the animals' breeding and food supply to ensure desired traits in the next generation.
Types of Mammals
The three main classes of mammals, based on food preference, are herbivores, omnivores, and carnivores. Herbivores are strict plant eaters (sheep, goats); omnivores are opportunistic meat and plant eaters (humans, pigs); carnivores are almost exclusively meat eaters (wolves, cats). Mammals, thus, are both prey and predator in any food chain, depending on their size and aggressive behavior.
Herbivores. Plant-eating mammals provide most of the world's protein. Virtually every culture around the world tends one of the grazing (herbivorous) species of mammals as a protein source. Dairy cattle, water buffalo, sheep and goats, camels, yaks, reindeer, and llamas and alpacas all provide dairy products such as yogurt, cheese, butter, and milk in various societies.
Cattle originated in northern Europe and were domesticated by the northern Germanic and Celtic tribes in approximately 4000 B.C.E. Romans then brought them into southern Europe in the first century B.C.E. From the upper reaches of the Nile to the plains of southern and eastern Africa, cattle herding was common. Cattle became the basis of wealth for warrior-dominated societies in southern Africa. During the Middle Ages in Europe, cattle represented real wealth as milk providers and as work animals, not as meat animals. Cattle were slaughtered only when they could no longer work. Beef was not widely eaten, as cattle and oxen (castrated dairy bulls) had tough, dry flesh.
Water buffalo, valuable for hauling, transportation, and other work, were also used for milk, and buffalo milk mozzarella is still enjoyed as a table cheese in Italy.
Sheep and goats, small ruminants, are kept for their fleece, hides, meat, and milk. Both are docile and socially inclined mammals, and were herded beginning in 8000 B.C.E. in southwest Asia. Camel, yak, and reindeer are herding animals that provide meat, milk, and hides for the nomadic tribes of Asia and the Arctic Circle, respectively. Reindeer herding developed in the northern latitudes even before herds were kept on the Eurasian steppes. Camel herding became common in Arabia and the Sudan of Africa, and camels were critical to the maintenance of trade routes that crossed the great deserts of Africa and Asia. The yak, a large, long-haired ox with a bushy tail, is native to the Tibetan plateau. It provides dairy products and is used for transport. Llamas and alpacas have provided the peoples of Peru and Bolivia with hides, fleece, meat, and milk since at least 3500 B.C.E.
The American bison, the largest land mammal of North America, is believed to have migrated from the steppes of Central Asia into what is now Alaska by crossing the narrow strip of land (Beringia) that existed during the last Ice Age. Native Americans revered bison for the wealth it provided in clothing, food, and tools made from sinew and bone.
Deer, along with their cousinslk, moose, and cariboure antlered, hoofed ruminants. These grazing animals supplied food and clothing to both Native Americans and, later, the European invaders of the North American continent. Antelope are the surviving members of an ancient family of grazing animals native to North America. Lewis and Clark, on their long exploratory trip across the continental United States, found large herds of antelope on the Great Plains. Gazelles and other wild grazing animals of Central Africa and Central Asia are hunted by native peoples for their meat.
Many species of small game have provided meat and fur when large game was not available. Wild hares and some rabbits, both native to Europe and the Americas,
The beauty of its fur led to the beaver's being overhunted by British, French, and Russian trappers in the northern territories of the North American continent in the sixteenth and seventeenth centuries. Beaver pelts were in great demand in Europe, especially for men's top hats. The fatty tail of the beaver was also prized for food. In the Middle Ages, the tail was declared "fish" by the Catholic Church, since the animal lived in water, making it acceptable as a meal on meatless days. Because its meat is very strong, only farm-raised beavers are recommended for cooking.
Kangaroos and opossums, both marsupials, are not consumed widely, though in Australia a cottage industry has developed around the production of kangaroo meat. Opossums, though not farm-raised, are hunted in the southern states of the United States for their meat.
Omnivores. Pigs are descended from a distant ancestor in southern Asia. Domesticated pigs brought to North America by the Spanish occasionally escaped captivity and multiplied, increasing the populations of wild pigs in the southeastern United States. Other breeds subsequently brought to the United States also occasionally escaped and bred with feral pigs, further mongrelizing the pig population.
Peccaries, known also as javelinas, North America's native wild pig, are not related to domesticated pigs and wild boars. Peccaries belong to a separate genus indigenous only to North America. They favor a warm climate and are hunted in New Mexico, Arizona, and Texas.
Raccoons range widely throughout the United States. Although valued primarily for their fur, their meat was commonly eaten during colonial times, and raccoons are still hunted for their fur and meat in the southern states of the United States.
Archeological evidence suggests that bear meat was consumed by native peoples in North America following ritual hunts. Bear meat was prized by European colonists and Native Americans, mainly for its fat for cooking. Though not a widely popular meat, bear are culled from game reserves and the meat is sometimes available frozen.
Carnivores. The small Asiatic wolf, a social animal and meat eaterhe ancestor of our canine companionsas reportedly domesticated as early as 11,000 B.C.E., probably because it was more useful for herding and hunting than as a source of food. This is not to say that the dog was not a source of meat. Dog meat has been eaten and enjoyed in Asian cultures, and is still commonly consumed in both China and Korea.
Although the history of domestication of mammals by humans is not recorded, archeological evidence suggests that it occurred on all continents between 7000 and 10,000 B.C.E. Each human group chose local migrating herbivores for domestication on the basis of their availability and docility. The first mammals to live with people were likely wolves and small ruminants such as sheep and goats. By the end of the second millennium B.C.E., civilizations based on livestock domestication and agriculture had emerged in Asia, Europe, and Africa. Small grazing animals like deer and sheep, which could provide meat, milk, and fiber, were probably herded by humans as they roamed the broad landscapes of western Asia. No evidence exists that early humans domesticated the numerous grazing animals of Africa.
Goats and sheep. Besides being docile and adaptable, goats and sheep breed successfully in the company of humans, and in time each generation gradually lost more of its feral nature. It is widely believed that the goat was the first herding animal to be domesticated, due to its gregarious nature. As the Romans moved north through Europe during the first century B.C.E., sheep and goats accompanied them, becoming sources for the wool industry, and mutton became a readily available meat. Sheep store fat well and so are efficient animals to maintain.
Goats are browsers, able to digest not only grasses but also woody shrubs and less desirable plants. Goats are even more adaptive and less choosy about their diet than sheep and can graze in arid climates. Goats continue to be prized for their milk and the resulting fermented dairy products. Goat meat, particularly the tender and milder flavor of kid, was enjoyed throughout the Mediterranean and the Asian continent and is also eaten in some regions of the Americas.
Cattle. The ancestor of today's domestic cattle, the aurochs (Bos primigenius), is extinct. Members of the bovine genus inhabited most of the world's continents and were introduced into the Western Hemisphere during the European conquests of the late fifteenth and early sixteenth centuries.
Asian cattle, also known as humped back cattle (Bos indicus), have provided meat and motive power on the Asian subcontinent. Religious and cultural beliefs in India prevent cattle from being consumed as food, although the milk can be used. In Africa, cattle are probably descended from European and Indian breeds introduced by traders, probably in the first millennium B.C.E.
Veal, meat from castrated young dairy bulls, was a choice dish even in ancient times. Just-weaned calves produce veal, which still brings a handsome price, more per pound than beef. Veal is a light-colored meat because the animals are fed milk or milk-replacer diets and are never permitted to graze.
The distinction between beef and dairy cattle breeds began in eighteenth-century Europe. Breeds that were best for beef and those best for milk production were identified and cultivated. Among the dairy-consuming peoples of northern Europe, the dairy breeds of cattle were selected for the high butterfat content of their milk.
It is generally believed that cattle first came to the North American continent with the Spanish. Columbus carried cattle to Santo Domingo in 1493, and in 1519 Cortés brought long-horned Andalusian cattle to Mexico. In the early seventeenth century, Spanish missionaries were raising cattle throughout the southwest United States.
Pigs. The ancestors of domestic swine were dispersed throughout Europe, Asia, and North Africa. The nomadic lifestyle of early peoples precluded their domestication. They were probably first encountered as pillagers of crops and therefore hunted, but young pigs might have been taken into early settlements and raised for meat. The omnivorous habits of the pig meant that it could thrive on the scraps from humans combined with its own rooting and foraging.
Pigs have evolved gradually over a period of ten million years with a few minor variations. Early pigs were taller than six feet, with an elongated wedge-shaped head, lacking a modern pig's snout, and a body shape similar to that of the European boar. This ancestor of the pig ranged from Europe to Asia and became the ancestor of the European wild boar.
Columbus is credited with bringing the pig to the Americas in 1493. These hogs ran wild throughout the Spanish West Indies, and were later joined by a load of pigs that arrived in Mexico with Cortés in 1521. On his trek west to the Mississippi Delta in 1539, Hernando de Soto brought pigs from the West Indies to Florida.
Dogs. Evidence suggests that early canine-human interactions may have occurred over the kills of larger wild herbivores, leading dogs and humans to be wary competitors at first but ultimately to become allies. Bones of dogs are common in campsites of the late Stone Age from around 7000 to 6000 B.C.E. The Asian wolf was probably the first wild animal domesticated by humans, and it is believed to be the ancestor of all domestic dogs. Until the eighteenth or nineteenth centuries, most of the breeds of dog were described by their purpose (wolf-hound, sheepdog), and it was not until the nineteenth century that many breeds were developed.
Horses. The earliest fossil examples, Eohippus, are found in northwestern North America. This wild ancestor of the horse was not much larger than a cat and had four toes on its forefeet and three on its hind feet. It was probably very widely distributed across the globe. Around 4000 B.C.E. the horse was domesticated in eastern Europe, and played a significant role in transportation, draft power, and warfare. Mounted soldiers were important military weapons until the twentieth century. Modern horses were reintroduced to the Americas by the Spanish conquistadors and were quickly adopted by native peoples for transport.
Game mammals and hunting. Those mammals not domesticated were hunted. Hunting animals for food or sport, or to rid a locale of animals that are seen as pests, is a human activity that spans the centuries and the globe. As early as the Late Paleolithic period, successful hunts required methods to preserve meat after slaughter. Meat was dried, smoked, or frozen in pits dug in the earth, or carcasses were weighted down with stones and sunk in cold lakes that froze during the winter. Meat stored was eaten dry, boiled, or grilled.
Hunting still provides some animal protein for the human diet; amounts vary depending upon the culture and region. In developed countries, hunting is largely a sport, while in less developed countries it remains, with fishing, an important source of dietary protein.
Meat. Meat is a popular high-quality protein food that satisfies the appetite and taste of people around the world. With the exception of organ meats, which tend to have concentrated nutrients, all of the cuts of meat from an animal are equally nutritious, providing roughly equivalent amounts of protein, minerals, and vitamins. Nutrition experts recognize meat as a food that also contributes varying amounts of fat to the diet. Meat supplies complete protein (all essential amino acids), essential minerals such as iron and phosphorus, significant B-complex vitamins (for example, thiamin), and trace minerals such as zinc. The protein of meat is comparable to that of fish, poultry, eggs, and milk.
The consumption of organ meats is sometimes encouraged because of the extremely rich vitamin and mineral content contained in edible glands and organs, including the liver, heart, kidneys, brain, sweetbread (thymus gland), tongue, tripe (stomach), and testicles, as well as the lungs and spleen in some cultures.
Dairy. Dishes prepared with milk or cheese are sometimes called "meat alternates" because of the similarity of the nutrient profiles, particularly when it comes to complete protein. The most significant milk products are:
- Yogurt: A fermented milk product made from whole, low-fat, or skim milk, providing all the food value of the milk from which it was made.
- Cultured cream: A product similar to yogurt but made with cream and so higher in butterfat. Sour cream is used widely in eastern European cooking; crème fraîche is more popular in France.
- Butter: A concentrated milk fat that provides fat in the diet and fat-soluble vitamin A.
- Cheese: A concentrated form of milk, fermented and often aged, that loses some of its protein in the cheese-making process but remains a high-protein food.
Mammals and Human Societies
Mammals have long played an important role in human mythology, religion, and social customs. As an act of reverence, humans have sacrificed animals, drunk their blood, and eaten their flesh. There are also taboos against certain relationships between humans and some animals, from the kosher prohibitions on eating pork and certain cuts of other animals to sexual taboos concerning congress between man and beast. Animals have been believed to be the habitat of both evil spirits and the souls of deceased human beings. Superstitions abound about animals, from bad luck brought by a black cat crossing one's path to good luck brought by carrying a rabbit's foot.
Culture, religion, symbolism, tradition, and taboos. Animal worship figures in many cultures and religions, including the cow among Hindus and the cat in ancient Egypt, and involves the role of reincarnation in some Asian religions. In many cultures, the spirits of important food animals were appeased to ensure their continued fertility, or ceremonies were performed to propitiate predators that threatened human survival. Stone Age art, cave drawings dating from 20,000 to 40,000 B.C.E., shows the animals and activities most important to the peoples of those cultures. The archeological evidence strongly suggests that these early people hunted and killed wild animals. Anthropologists believe the caves in which these drawings are found were not dwellings but served a religious or ritual function because food animals and hunting scenes predominate.
The earliest records of meat consumption indicate that animals were ritually slaughtered and the meat distributed to members of the community on the basis of an individual's place in the social hierarchy. Such practices required settled groups engaged in crop and pasture production. With farming and the formation of population clusters came the division of labor necessary to support specific food practicesrain milling, baking, meat processing, leather tanning, and so on. In some societies, meat processing emerged as part of sacrificial offerings to the deities for atonement, appeasement, supplication, or thanksgiving.
Meat eating and religious practices. In ancient times, sacrifices to the gods and goddesses often consisted of roasted sheep, goats, and lambs. Homer, Virgil, and the authors of the Old Testament all give accounts of roasted meat being offered to please the gods or the Lord. The biblical Book of Leviticus stipulates that the sacrificial animal be perfect, without any physical flaws; thus, a castrated animal was forbidden as a sacrifice.
The story of Adam and Eve in the Book of Genesis suggests that humans were created essentially vegetarian. Meat eating followed Eve's transgression. Under the laws of Kashrut, which govern kosher practices, Jews are forbidden to eat pork and shellfish ("tref"). In addition, certain parts of an animal, such as the hindquarters (unless butchered in a special fashion) as well as some organ meats, are forbidden. Another dietary restriction is that meat and milk may not be eaten together. These limits have resulted in fewer choices when it comes to meat for Jews than for others.
Muslims also do not eat pork, and, like Jews, they slaughter their meat according to religious guidelines. Such meat is called halal, or lawful. The month-long fast of Ramadan, while strict, is more of a joyful occasion than the Christian Lent, a forty-day period of abstinence and penitence.
The Roman Catholic Church established many restrictions on eating meat on certain days during the year, particularly during Lent and on specified fast days. Until the reforms of Vatican II (1962), meat eating was traditionally forbidden on Fridays. For generations, fish on Fridays was the rule in Roman Catholic communities. Meat, broth, and fat from warm-blooded animals were forbidden, while meat from waterfowl and from cold-water fish was considered acceptable.
Given the Church calendarbstaining from meat on Fridays, on the eve of certain feast days, and on other days as welleat eating was forbidden almost every other day: 180 days a year. The Orthodox Church was even stricter. This refusal to eat meat and fat (including butter in some times and places) had an ascetic aspect as well as a penitential one in its denial of human desire. In India cattle are not consumed because of the religious proscriptions of the Hindu faith. Since pigs, goats, and sheep are raised for meat and milk, however, India is not entirely vegetarian. Butter from the milk of sacred Indian cows was made for religious ceremonies, and ghee, a kind of clarified butter, is used for cooking.
Meat eating and vegetarianism. Meat, whether from mammals, poultry, or fish, provides a concentrated, easily digestible source of protein and fat. Ruminants in particular are able to convert herbaceous material into muscle more efficiently than monogastric animals, such as pigs or poultry, and are therefore better suited as sources of meat protein.
A vegetarian dietschewing meat or any animal food productss undertaken by individuals for many reasons: health reasons and concern for the environment, ecology, and world hunger issues. Vegetarians often also cite economic reasons and ethical considerations as reasons. For some, religious beliefs dictate following a diet that avoids animal products. In India, for example, many are vegetarians because they find the taking of life abhorrent; in addition, many believe in reincarnation and fear that a living soul could be inhabiting a living creature.
Significant scientific data suggest links between a vegetarian diet and reduced risk of developing several chronic degenerative diseases and conditions, including heart disease, high blood pressure, diabetes, obesity, and some types of cancer.
The eating patterns of vegetarians vary considerably. The lacto-ovo-vegetarian diet is based on grains, vegetables, fruits, legumes, seeds, nuts, dairy products, and eggs, and excludes meat, fish, and fowl. The vegan, or total vegetarian, eating pattern is similar with the additional exclusion of eggs, dairy, and other animal products, even honey. Even within these patterns, considerable variation exists in the extent to which animal products are avoided.
Human beings, however, have been omnivorous since before recorded history. It seems unlikely that they will turn en masse to vegetarianism. In fact, arguments from the 1968 Rome conferences of the Food and Agriculture Organization of the United Nations suggest that humans could not abandon the consumption of meat in favor of a solely vegetarian diet. There was not, nor is there now, sufficient arable land to produce adequate protein or calories for the world's population.
While some of the problems discussed here primarily reflect events and situations in Europe and the United States, their repercussions will almost certainly have global consequences as impoverished regions of the world struggle to provide a nutritious diet for their increasing populations. What began as animal husbandry in prehistory threatens worldwide disaster. As the human population has increased beyond the capacity of the planet to feed its numbers, the practice of high-intensity animal production has caused numerous environmental problems that endanger humans as well as the animals bred for food.
The risks and costs of high-intensity animal production. Since World War II, agricultural production has striven to produce more from less without, some critics say, thought of the consequences. With high-intensity animal production, because animals are kept in close quarters they are more susceptible to the various diseases and parasites afflicting livestock. To counter disease and parasitism, scientists developed inexpensive pharmaceuticals to protect and treat animals. Surprisingly, many of these drugs actually improved livestock feed conversion performance faster than breeding and breed selection. As a consequence, livestock producers adopted these products widely, and meat production operations grew and consolidated in rural areas near feed grain sources.
Feedlots and large poultry operations, however, though extraordinarily efficient, are smelly and environmentally risky as well. Also, starting in the early 1970s, mounting public concern about the residues of pharmaceutical products in meat used for human consumption entered the debate about the wisdom of intensive livestock production. The food supply seemed to be contaminated with unnecessary, and perhaps toxic, chemical substances, and the methods of raising animals that required their use became targets of public protests. One result of these concerns has been the increase in sustainable livestock production, sometimes called "natural" or "organic" production. In natural production the animals are raised without performance-enhancing chemicals or feed additives. Livestock living in herds are as susceptible to disease as those raised in close quarters, and the effects of disease are devastating to herds. However, ranchers claim that it is more expensive to raise pigs or cattle without the aid of drugs or additives and so justify the higher prices charged for such meat.
Organic livestock production is stricter still, involving the feeding of grains and oil seeds produced under National Organic Standards. As adopted by the U.S. Department of Agriculture (USDA), the National Organic Standards specify that livestock and poultry may not be treated with antibiotics or any medicine and must be fed grains and rations that derive from organic crop production.
Intensive livestock production systems are based on concentrating large numbers of animals (housed or not) on small parcels of land and feeding them high-energy diets that guarantee the fastest weight gain in the least time. While feed efficiency (pounds of gain per pounds of feed) is important to the owners of such systems, intensified livestock production also results in large-scale animal waste. The concentration of live animals in a total confinement unit rivals a small city in terms of the annual waste output. Cities of such size are required by law to maintain tertiary water treatment facilities to handle their wastewater outfall. No such provision has yet forced pig or cattle feeders to treat their production wastes in a similar manner.
Among mammals, pigs represent the biggest waste threat to the environment because of the very large confinement units used to raise them. The most efficient pig will convert two pounds of feed into one pound of additional body mass, not all of which is edible protein. In order to acquire that pound, the animal produces one pound of feces and urine. Cattle are even less efficient, converting twelve to eighteen pounds of feed to one pound of body weight during the last weeks of feeding. This waste presents a considerable disposal problem.
With the animals living in such limited space, the waste must be stored for later treatment or use. In the past, this meant applying the manure as fertilizer to agricultural land, but this method of handling manure is no longer sound. Lagoons that hold animal waste often leak or break, with disastrous consequences for local streams and lakes. The open pools of raw waste also fill the surrounding countryside with a prevailing stench. The recent history of such environmental disasters and resulting legal battles is a complex story about shifting the costs of production to others, including future generations. Moreover, the available solutions cost money, so are unacceptable to those watching the bottom line. Steel holding tanks or glass-lined tanks, for example, clearly better containment choices, are prohibitively expensive, usually more than the average pork or beef production operation can, or is willing to, pay. With the infusion of new capital into pork production in the late 1980s, more attention was given to waste management, but the disposal problem has not yet been solved.
Intensive livestock production poses other risks to the environment and human health, for example, pollution of surface and ground water by animal waste. Such spills contaminate water, cause loss of property values for residential land, and harm recreational areas. The frequent and periodic contamination of ground and surface water from manure spills has become a familiar headline, reminding the public that profit-driven production methods endanger their health and the welfare of future generations.
With the appearance in the 1990s of bovine spongiform encephalopathy (BSE; more familiar to the public as "mad cow disease") in England and France, and the deaths caused by its spread to humans who ate meat from diseased cows, vigilance with respect to safe meat production became even more critical. In spite of research demonstrating that the disease had been spread in herds that had eaten feed that contained meat products, some feed suppliers in the United States were found continuing the practice in 2001, and, without enough USDA inspectors to monitor meat production from start to finish, the public cannot be sure that the meat they eat does not come from cows infected with BSE.
Facing continual pressure from environmentalists, real estate developers, and non-farm landowners, livestock producers struggle with presenting a responsible image. This reality applies both to producers managing large, intensified operations and to those who pasture their livestock. In terms of the stocking capacity of open land, whether for cattle, pigs, or small ruminants, it is now being argued that small ruminants (sheep and goats) can provide as much meat per acre as cattle or pigs without the subsequent environmental risks. Raising dual-purpose sheep or goats (those that provide both food and fiber) can be a more efficient use of limited land resources than the typical practices of cattle ranching.
This issue will become more pressing in the future as residential suburbs push into traditionally rural areas. The resolution will need to be political because of the constituencies involved. Technological advances have made the cost of farming too expensive for family farmers. As they are forced to sell their land to the giants of agribusiness or go into bankruptcy, farmers are becoming a smaller and smaller percentage of the population, and their real voice in legislatures will continue to diminish. City dwellers will demand that a fairer burden of the cost of farming be placed on those who profit from it than has been the practice since the New Deal under Franklin D. Roosevelt's administration in 1932940.
Another aspect of the urban-rural confrontation involves the cropping practices needed to support the intensified meat-production industry. Of the more than 70 million acres of corn grown annually in the United States, more than 65 percent is used for animal feed, and the price of corn drives all other commodity prices. Federal farm policies during the twentieth century resulted in overproduction of corn and soy relative to world market demands, depressed world prices, and significant loss of farm income. Add to this the loss of agricultural diversity and soil productivity caused by producing the same crop or the same rotation of crops on the same land year in and year out. Such farming practices had forced farmers to use more and more chemical pesticides and fertilizers in order to achieve uniform yields. Biotech crops may be a solution, because they permit more intensified cultivation and higher yields. However, controversy remains within the scientific community about the sustainability of high yields from biotech seed crops. This concern is added to the ongoing problems of groundwater contaminated with fertilizer runoff and pesticides.
Bioengineering. Unlike plant biotechnology, which has quickly introduced numerous varieties of common plants genetically reengineered to include certain traits, such as resistance to common pests for corn, animal biotechnology has had little success in changing the basic properties of livestock or poultry. A few applications of genetic manipulation may eventually prove useful in producing meat protein for human consumption. Of these, cloning is the most obvious and most likely to succeed, if public opposition fails to halt such research. Cloning livestock requires the nuclear transfer from an animal with the most desired traits (for example, efficient feed conversion, muscling, and tenderness) to eggs from the same species. One application would be the cloning of highly desirable boar and sow lines to be used in creating market pigs with specific, repeatable characteristics.
The technology for cloning livestock at this time is prohibitively expensive compared to conventional breeding or artificial insemination. For this reason, cloning is not expected to make a significant contribution to meat production for years. Such genetic manipulation also arouses considerable controversy in public and scientific discourse regarding the ultimate safety of food derived from such genetically modified organisms.
As populations continue to expand and the food crisis intensifies, the twenty-first century will witness societies worldwide struggling with the multitude of social, environmental, economic, and health issues that surround the production of livestock.
See also Aversion to Food; Cattle; Christianity; Dairy Products; Disgust; FAO (Food and Agriculture Organization); Food Safety; Goat; Government Agencies; High-Technology Farming; Horse; Hunting and Gathering; Inspection; Judaism; Mammals, Sea; Meat; Organic Agriculture; Pig; Prehistoric Societies; Sheep; Vegetarianism.
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