Pig

Pigs are a genus of even-toed ungulates within the family Suidae. The name hog most commonly refers to the domestic pig (Sus domestica) in everyday parlance, but technically encompasses several distinct species, including the wild boar. Swine is a collective noun generally used to describe pigs as a group rather than an individual, however it may often be implied in a pejorative manner to any living being expressing pig-like behavior.

With around 2 billion on the planet, domestic pigs are also by far the most numerous pig species.^[1][2] Pigs are omnivores, and despite their reputation for gluttony, they are generally social and intelligent animals.

Description and behavior

A pig has a snout for a nose, small eyes, and a small tail, which may be curly, kinked, or straight. It has a thick body, short legs, and coarse hair. There are four toes on each foot, with the two large middle toes used for walking.^[3]

Breeding occurs throughout the year in the tropics, but births peak around rainy seasons. A female pig can become pregnant at around 8–18 months of age. She will then go into estrus every 21 days if not bred. Male pigs become sexually active at 8–10 months of age.^[4] A litter of piglets typically contains between 6 and 12 piglets.^[5] After the young are weaned, two or more families may come together until the next mating season.

Pigs do not have functional sweat glands,^[6] so pigs cool themselves using water or mud during hot weather. They also use mud as a form of sunscreen to protect their skin from sunburn. Mud also provides protection against flies and parasites.^[5]

Domesticated pigs are commonly raised as livestock by farmers for meat (called pork), as well as for leather. Their bristly hairs are also used for brushes. Some breeds of pig, such as the Asian pot-bellied pig, are kept as pets.

Diet and foraging

Pigs are omnivores, which means that they consume both plants and animals. Pigs will scavenge and have been known to eat any kind of food, including dead insects, worms, tree bark, rotting carcasses, garbage, and even their own feces and piglets. It is estimated that 50% of piglet fatality is due to the mother sow attacking or unintentionally crushing the newborn pre-weaned animals. In the wild, they are foraging animals, primarily eating leaves, grasses, roots, fruits and flowers.

A typical pig has a large head with a long snout which is strengthened by a special prenasal bone and by a disk of cartilage in the tip.^[4] The snout is used to dig into the soil to find food and is a very sensitive sense organ.

Pigs have a full set of 44 teeth. The canine teeth, called tusks, grow continuously and are sharpened by the lowers and uppers rubbing against each other.^[4]

Pigs that are allowed to forage may be watched by swineherds. Because of their foraging abilities and excellent sense of smell, they are used to find truffles in many European countries.

Species

Iberian pigs.

• Palawan Bearded Pig (Sus ahoenobarbus)^[7]
• Bearded Pig (Sus barbatus)^[8]
• Indo-Chinese (or Vietnam) Warty Pig (Sus bucculentus).^[9]
• Visayan Warty Pig (Sus cebifrons)^[10]
• Celebes (or Sulawesi) Warty Pig (Sus celebensis)^[11]
• †Sus falconeri
• †Sus hysudricus
• Oliver's (or Mindoro) Warty Pig (Sus oliveri)^[12]
• Philippine Warty Pig (Sus philippensis)^[13]
• Wild boar (Sus scrofa)^[14]
  • Domestic pig (Sus scrofa domestica)^[14]
    • Iberian Pig or Black Iberian Pig
    • Black Balearic Pig
    • Black Canary Island Pig
• †Sus strozzi
• Java Warty Pig (Sus verrucosus)^[15]

The Pygmy Hog is now in the monotypic genus Porcula again.^[16]

Domestic pigs

Swedish pigfarmer with piglet. Early 20th century

Pigs have been domesticated since ancient times in the Old World. Archeological evidence suggests that pigs were being managed in the wild in a way similar to the way they are managed by some modern New Guineans from wild boar as early as 13,000–12,700 BP in the Near East in the Tigris Basin.^[17] Remains of pigs have been dated to earlier than 11,400 BP in Cyprus that must have been introduced from the mainland which suggests domestication in the adjacent mainland by then.^[18] A separate domestication also occurred in China.^[19].

In India pigs have been domesticated since a long time mostly in Goa and some rural areas for pig toilets. Though ecologically logical as well as economical pig toilets are waning in popularity as use of septic tanks and/or sewerage system is increasing in rural areas.

Pigs were brought to southeastern North America from Europe by Hernando de Soto and other early Spanish explorers. Pigs are particularly valued in China and on certain oceanic islands, where their self-sufficiency allows them to be turned loose, although the practice is not without its drawbacks (see Environmental impact).

The domestic pig (Sus scrofa domesticus) is usually given the scientific name Sus scrofa, although some authors call it S. domesticus, reserving S. scrofa for the wild boar. It was domesticated approximately 5,000 to 7,000 years ago. Their coats are coarse and bristly. They are born brownish colored and tend to turn more grayish colored with age. The upper canines form sharp distinctive tusks that curve outward and upward. Compared to other artiodactyles, their head is relatively long, pointed, and free of warts. Their head and body length ranges from 0.9 to 1.8 m and they can weigh between 50 and 350 kg.

Pigs are intelligent^[20] and can be trained to perform numerous tasks and tricks^[21]. Recently, they have enjoyed a measure of popularity as house pets, particularly the dwarf breeds.

Cultural references to pigs

Pigs are frequently referenced in culture and are a popular topic for idioms and famous quotes.

Pigs in religion

Painting of Saint Anthony with pig in background by Piero di Cosimo c. 1480

• In Nordic Mythology, Gullinbursti ("Gold-Bristle" or "Gold-Mane") was Freyr's golden boar, created by the dwarves Brokk and Sindri as part of a challenge. His shining fur is said to fill the sky, trees, and sea with light.
• In ancient Egypt pigs were associated with Set, the rival to the sun god Horus. When Set fell into disfavor with the Egyptians, swineherds were forbidden to enter temples. According to Herodotus, swineherds were a kind of separate sect or caste, which only married among themselves. Egyptians regarded pigs as unworthy sacrifices to their gods other than the Moon and Dionysus, to whom pigs were offered on the day of the full Moon. Herodotus states that, though he knew the reason why Egyptians abominated swine at their other feasts but they sacrificed them at this one; however, it was to him "not a seemly one for me to tell".^[22]
• In Hinduism the god Vishnu took the form of a boar varaha in order to save the Earth from a demon who had dragged it to the bottom of the sea.
• In ancient Greece, a sow was an appropriate sacrifice to Demeter and had been her favorite animal since she had been the Great Goddess of archaic times. Initiates at the Eleusinian Mysteries began by sacrificing a pig.
• The pig is one of the 12-year cycle of animals which appear in the Chinese zodiac related to the Chinese calendar. Believers in Chinese astrology associate each animal with certain personality traits (see: Pig (zodiac)).
• In keeping with Leviticus 11:7, the dietary laws of Judaism (Kashrut, adj. Kosher) forbid, among other kinds of meat, the eating of pork in any form, considering the pig to be an unclean animal (see taboo food and drink). From the strict reading to the relevant Torah passage, pork is as forbidden as the flesh of any other unclean animal, but probably due to excessive use of pork in modern days, abhorrence of pork is far stronger and emotional in traditional Jewish culture than that of other forbidden foods.
• The Bible prohibits the consumption of pork, in the book of Leviticus: "And the swine, though he divide the hoof, and be cloven footed, yet he cheweth not the cud; he is unclean to you". "Of their flesh shall ye not eat, and their carcass shall ye not touch, they are unclean to you."[Leviticus 11:7-8]. Pork is also prohibited in the Bible in the book of Deuteronomy: "And the swine, because it divideth the hoof, yet cheweth not the cud, it is unclean unto you. Ye shall not eat of their flesh, nor touch their dead carcass."[Deuteronomy 14:8]. A similar prohibition is repeated in the Bible in the book of Isaiah chapter 65 verse 2-5. Also among Seventh-day Adventists and some other Christian denominations eating of pork is prohibited. Some people believe that eating of pork is not prohibited in Christianity according to the teachings of the New Testament. It is said that in Catholicism, Eastern Orthodoxy, and other older Christian groups, pigs are associated with Saint Anthony the Great, and he is known as the patron saint of swineherds but there are some stories included in Saint Anthony's biography which are perpetuated now mostly in paintings, where they give an opportunity for artists to depict their more lurid or bizarre interpretations.
• The eating of pork is also prohibited in Islam (see Haraam). The Qur'an prohibits the consumption of pork in no less than 4 different places. It is prohibited in 2:173, 5:3, 6:145 and 16:115. "Forbidden to you (for food) are: dead meat, blood, the flesh of swine, and that on which hath been invoked the name of other than Allah." [Al-Qur'an 5:3]
• In Haitian Vodou, Ezili Dantor, the lwa of motherhood, is associated with the black Creole Pig of Haiti, her favorite animal sacrifice.

Environmental impacts

Domestic pigs that have escaped from farms or were allowed to forage in the wild, and in some cases wild boars which were introduced as prey for hunting, have given rise to large populations of feral pigs in North and South America, Australia, New Zealand, Hawaii, and other areas where pigs are not native. Accidental or deliberate releases of pigs into countries or environments where they are an alien species have caused extensive environmental change. Their omnivorous diet, aggressive behaviour, and their feeding method of rooting in the ground all combine to severely alter ecosystems unused to pigs. Pigs will even eat small animals and destroy nests of ground nesting birds.^[4] The Invasive Species Specialist Group lists feral pigs on the list of the world's 100 worst invasive species and says:^[23]

Feral pigs (razorbacks) in Florida

Health issues

Pigs can harbour a range of parasites and diseases that can be transmitted to humans. These include trichinosis, Taenia solium, cysticercosis, and brucellosis. Pigs are also known to host large concentrations of parasitic ascarid worms in their digestive tract.^[24] The presence of these diseases and parasites is one reason pork meat should always be well cooked or cured before eating. Some religious groups that consider pork unclean refer to these issues as support for their views.^[25]

Pigs are susceptible to bronchitis and pneumonia. They have small lungs in relation to body size; for this reason, bronchitis or pneumonia can kill a pig quickly.^[26] There is concern that pigs may allow animal viruses such as influenza or Ebola Reston to infect humans more easily. Some strains of influenza are endemic in pigs (see Swine influenza), and pigs also can acquire human influenza.

Pigs can be aggressive and pig-induced injuries are relatively common in areas where pigs are reared or where they form part of the wild or feral fauna.^[27]

See also

References

External links

• Pig genome resources
• Swine breeds, with pictures