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Sheep: the story on HearLore | HearLore
Sheep
The domestication of sheep began between 11,000 and 9,000 BC in Mesopotamia, marking one of humanity's earliest transitions from hunting to herding. Archaeological evidence from Mehrgarh in the Indus Valley suggests this process may have started as early as 7,000 BC, where early farmers began selecting wild mouflon for specific traits. These ancient herders did not initially seek wool; the first sheep were kept solely for meat, milk, and skins. It was not until around 6,000 BC that selection for woolly sheep began in southwest Asia, a development confirmed by statuary found in Iran. The earliest woven wool garments, dating back two to three thousand years after the initial selection, would eventually transform the global economy. By 6,000 BC, the Castelnovien people living near present-day Marseille in southern France were already keeping domestic sheep, spreading the practice quickly across Europe. Ancient Greek civilization relied on sheep as primary livestock, with some accounts suggesting they named individual animals, a level of intimacy rarely seen in modern agriculture. The Romans later expanded this practice on a wide scale, acting as a primary agent in the spread of sheep raising to the New World from 1493 onwards.
Anatomy of the Fleece
Domestic sheep are relatively small ruminants, typically possessing a crimped hair called wool and often featuring horns that form a lateral spiral. Unlike their wild ancestors, domestic sheep have become uniquely neotenic, retaining juvenile characteristics through selective breeding. While wild sheep are largely variations of brown hues, domestic breeds display a wide variation in color ranging from pure white to dark chocolate brown, and even spotted or piebald patterns. Selection for easily dyeable white fleeces began early in domestication, and as white wool is a dominant trait, it spread quickly through commercial markets. However, colored sheep do appear in many modern breeds, sometimes as a recessive trait in white flocks, catering to a niche market for handspinning. The nature of the fleece varies widely among breeds, from dense and highly crimped to long and hairlike. A few primitive breeds retain some characteristics of their wild cousins, such as short tails, and some breeds may have no horns at all. Most horned breeds have a single pair, but a few breeds may have several. The rate of growth and mature weight is a heritable trait often selected for in breeding, with ewes typically weighing between 45 and 100 kilograms and rams between 60 and 120 kilograms. When all deciduous teeth have erupted, the sheep has 20 teeth, while mature sheep have 32 teeth.
The Intelligence of the Flock
Despite the common perception that sheep are unintelligent, a University of Illinois monograph reported their intelligence to be just below that of pigs and on par with that of cattle. In a study published in Nature in 2001, researchers found that individual sheep can remember 50 other different sheep faces for over two years. They possess specialized neural systems in the temporal and frontal lobes similar to humans, allowing them to recognize and be attracted to individual sheep and humans by their faces. Sheep can also differentiate emotional states through facial characteristics, and if worked with patiently, many can learn their names. They have responded well to clicker training and have been used as pack animals, with Tibetan nomads distributing baggage equally throughout a flock as it is herded between living sites. Some sheep have even demonstrated problem-solving abilities, with anecdotal accounts describing a flock in West Yorkshire, England, that found a way to get over cattle grids by rolling on their backs. Their visual field ranges from 270 to 320 degrees, allowing them to see behind themselves without turning their heads, though some breeds suffer from wool blindness if their facial wool is not shorn. They have good hearing and are sensitive to noise when being handled, and their sense of smell is excellent, with scent glands located just in front of the eyes and interdigitally on the feet.
When did the domestication of sheep begin in Mesopotamia?
The domestication of sheep began between 11,000 and 9,000 BC in Mesopotamia. Archaeological evidence from Mehrgarh in the Indus Valley suggests this process may have started as early as 7,000 BC. These ancient herders did not initially seek wool but kept the animals solely for meat, milk, and skins.
What are the weight ranges for adult ewes and rams?
Ewes typically weigh between 45 and 100 kilograms while rams weigh between 60 and 120 kilograms. The rate of growth and mature weight is a heritable trait often selected for in breeding programs. Most horned breeds have a single pair of horns but a few breeds may have several.
When was the first mammal cloned from an adult somatic cell?
A Finnish Dorset sheep named Dolly became the world's most famous sheep in 1996 as the first mammal to be cloned from an adult somatic cell. In 1995, two ewes named Megan and Morag became the first mammals cloned from differentiated cells. As of 2008, the sheep genome had not been fully sequenced although a detailed genetic map had been published.
Which countries have the largest modern sheep flocks today?
China, Australia, India, and Iran have the largest modern flocks serving both local and exportation needs for wool and mutton. Other countries such as New Zealand have smaller flocks but retain a large international economic impact due to their export of sheep products. The nations with the highest consumption of sheep meat are the Arab states of the Persian Gulf, New Zealand, Australia, Greece, Uruguay, the United Kingdom, and Ireland.
What percentage of sheep deaths in the United States were caused by predation in 2004?
Over one third of sheep deaths in the United States in 2004 were caused by predation. Worldwide, canids including the domestic dog are responsible for most sheep deaths. Other animals that occasionally prey on sheep include felines, bears, birds of prey, ravens, and feral hogs.
The Roslin Institute of Edinburgh, Scotland, used sheep for genetics research that produced groundbreaking results in the late 20th century. In 1995, two ewes named Megan and Morag became the first mammals cloned from differentiated cells, a process referred to as gynomerogony. A year later, a Finnish Dorset sheep named Dolly became the world's most famous sheep, as she was the first mammal to be cloned from an adult somatic cell. Following this, Polly and Molly were the first mammals to be simultaneously cloned and transgenic. As of 2008, the sheep genome had not been fully sequenced, although a detailed genetic map had been published, and a draft version of the complete genome produced by assembling sheep DNA sequences using information given by the genomes of other mammals. In 2012, a transgenic sheep named Peng Peng was cloned by Chinese scientists, who spliced his genes with that of a roundworm to increase production of fats healthier for human consumption. Pregnant sheep are also a useful model for human pregnancy, used to investigate the effects on fetal development of malnutrition and hypoxia. In behavioral sciences, sheep have been used in isolated cases for the study of facial recognition, as their mental process of recognition is qualitatively similar to humans. They are sometimes used in medical research, particularly for researching cardiovascular physiology, in areas such as hypertension and heart failure.
The Black Sheep Paradox
In the English language, to call someone a sheep or ovine may allude that they are timid and easily led, yet male sheep are often used as symbols of virility and power. The logos of the Los Angeles Rams football team and the Dodge Ram pickup truck allude to males of the bighorn sheep, Ovis canadensis. Counting sheep is popularly said to be an aid to sleep, and some ancient systems of counting sheep persist today. The phrase black sheep implies that they are an odd or disreputable member of a group, deriving from the recessive trait that causes an occasional black lamb to be born into an entirely white flock. These black sheep were considered undesirable by shepherds, as black wool is not as commercially viable as white wool. Citizens who accept overbearing governments have been referred to by the portmanteau neologism of sheeple. Somewhat differently, the adjective sheepish is also used to describe embarrassment. In British heraldry, sheep appear in the form of rams, sheep proper, and lambs, distinguished by the ram being depicted with horns and a tail, the sheep with neither, and the lamb with its tail only. A further variant of the lamb, termed the Paschal lamb, is depicted as carrying a Christian cross and with a halo over its head. Rams' heads, portrayed without a neck and facing the viewer, are also found in British armories. The fleece, depicted as an entire sheepskin carried by a ring around its midsection, originally became known through its use in the arms of the Order of the Golden Fleece and was later adopted by towns and individuals with connections to the wool industry.
The Sacred Ram
Religious symbolism involving sheep cropped up in religions in the ancient Near East, the Mideast, and the Mediterranean area, with skulls of rams occupying central placement in shrines at the Çatalhöyük settlement in 8,000 BC. In Ancient Egyptian religion, the ram was the symbol of several gods, including Khnum, Heryshaf, and Amun, who was incarnated as a god of fertility. Other deities occasionally shown with ram features include the goddess Ishtar, the Phoenician god Baal-Hamon, and the Babylonian god Ea-Oannes. In Madagascar, sheep were not eaten as they were believed to be incarnations of the souls of ancestors. There are many ancient Greek references to sheep, such as that of Chrysomallos, the golden-fleeced ram, continuing to be told through into the modern era. Astrologically, Aries, the ram, is the first sign of the classical Greek zodiac, and the sheep is the eighth of the twelve animals associated with the 12-year cycle of the Chinese zodiac. It is said in Chinese traditions that Hou Ji sacrificed sheep. Mongolia, shagai are an ancient form of dice made from the cuboid bones of sheep that are often used for fortunetelling purposes. Sheep play an important role in all the Abrahamic faiths; Abraham, Isaac, Jacob, Moses, and King David were all shepherds. According to the Biblical story of the Binding of Isaac, a ram is sacrificed as a substitute for Isaac after an angel stays Abraham's hand, while in the Islamic tradition, Abraham was about to sacrifice Ishmael. Eid al-Adha is a major annual festival in Islam in which sheep are sacrificed in remembrance of this act. Greeks and Romans sacrificed sheep regularly in religious practice, and Judaism once sacrificed sheep as a Korban, such as the Passover lamb. Ovine symbols, such as the ceremonial blowing of a shofar, still find a presence in modern Judaic traditions. Collectively, followers of Christianity are often referred to as a flock, with Christ as the Good Shepherd, and sheep are an element in the Christian iconography of the birth of Jesus. Some Christian saints are considered patrons of shepherds, and even of sheep themselves. Christ is also portrayed as the Sacrificial lamb of God, and Easter celebrations in Greece and Romania traditionally feature a meal of Paschal lamb. A church leader is often called the pastor, which is derived from the Latin word for shepherd. In many western Christian traditions, bishops carry a staff, which also serves as a symbol of the episcopal office, known as a crosier, modeled on the shepherd's crook.
The Economics of Wool
Sheep are an important part of the global agricultural economy, though their once vital status has been largely replaced by other livestock species, especially the pig, chicken, and cow. China, Australia, India, and Iran have the largest modern flocks, serving both local and exportation needs for wool and mutton. Other countries such as New Zealand have smaller flocks but retain a large international economic impact due to their export of sheep products. In the late 20th century, wool prices began to fall dramatically as the result of the popularity and cheap prices for synthetic fabrics. For many sheep owners, the cost of shearing is greater than the possible profit from the fleece, making subsisting on wool production alone practically impossible without farm subsidies. Fleeces are used as material in making alternative products such as wool insulation. In the 21st century, the sale of meat is the most profitable enterprise in the sheep industry, even though far less sheep meat is consumed than chicken, pork, or beef. The nations with the highest consumption of sheep meat are the Arab states of the Persian Gulf, New Zealand, Australia, Greece, Uruguay, the United Kingdom, and Ireland, where people eat 14 to 40 pounds of sheep meat per capita per annum. Sheep meat is also popular in France, Africa, the Caribbean, the rest of the Middle East, India, and parts of China. In comparison, countries such as the United States consume only a pound or less, with Americans eating 50 pounds of pork and 65 pounds of beef. Though sheep's milk may be drunk rarely in fresh form, today it is used predominantly in cheese and yogurt making. Well-known cheeses made from sheep milk include the feta of Bulgaria and Greece, Roquefort of France, Manchego from Spain, the pecorino romano, and ricotta of Italy. Sheep milk contains 4.8% lactose, which may affect those who are intolerant. Of all sheep byproducts, perhaps the most valuable is lanolin, the waterproof, fatty substance found naturally in sheep's wool and used as a base for innumerable cosmetics and other products.
The Predator and the Prey
Other than parasites and disease, predation is a threat to sheep and the profitability of sheep raising. Sheep have little ability to defend themselves compared with other species kept as livestock. Even if sheep survive an attack, they may die from their injuries or simply from panic. In the United States, for instance, over one third of sheep deaths in 2004 were caused by predation. Worldwide, canids, including the domestic dog, are responsible for most sheep deaths. Other animals that occasionally prey on sheep include felines, bears, birds of prey, ravens, and feral hogs. Pre-modern shepherds used their own presence, livestock guardian dogs, and protective structures such as barns and fencing. Fencing, penning sheep at night, and lambing indoors all continue to be widely used. More modern shepherds used guns, traps, and poisons to kill predators, causing significant decreases in predator populations. In the wake of the environmental and conservation movements, the use of these methods now usually falls under the purview of specially designated government agencies in most developed countries. The 1970s saw a resurgence in the use of livestock guardian dogs and the development of new methods of predator control by sheep producers, many of them non-lethal. Donkeys and guard llamas have been used since the 1980s in sheep operations, using the same basic principle as livestock guardian dogs. Interspecific pasturing, usually with larger livestock such as cattle or horses, may help to deter predators, even if such species do not actively guard sheep. In addition to animal guardians, contemporary sheep operations may use non-lethal predator deterrents such as motion-activated lights and noisy alarms. Despite these measures, the impact of predation varies dramatically with region, with Africa, Australia, the Americas, and parts of Europe and Asia seeing predators as a serious problem, while other nations are virtually devoid of sheep predators, particularly islands known for extensive sheep husbandry.