Pig

Pig

Overview
A pig is any of the animals in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Sus, within the Suidae
Suidae
Suidae is the biological family to which pigs belong. In addition to numerous fossil species, up to sixteen extant species are currently recognized, classified into between four and eight genera...

 family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of even-toed ungulate
Even-toed ungulate
The even-toed ungulates are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in odd-toed ungulates such as horses....

s. Pigs include the domestic pig
Domestic pig
The domestic pig is a domesticated animal that traces its ancestry to the wild boar, and is considered a subspecies of the wild boar or a distinct species in its own right. It is likely the wild boar was domesticated as early as 13,000 BC in the Tigris River basin...

, its ancestor the wild boar, and several other wild relatives. Pigs are omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...

s and are highly social and intelligent animals.

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
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 at the tip. The snout is used to dig into the soil to find food and is a very acute sense organ.
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Encyclopedia
A pig is any of the animals in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Sus, within the Suidae
Suidae
Suidae is the biological family to which pigs belong. In addition to numerous fossil species, up to sixteen extant species are currently recognized, classified into between four and eight genera...

 family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of even-toed ungulate
Even-toed ungulate
The even-toed ungulates are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in odd-toed ungulates such as horses....

s. Pigs include the domestic pig
Domestic pig
The domestic pig is a domesticated animal that traces its ancestry to the wild boar, and is considered a subspecies of the wild boar or a distinct species in its own right. It is likely the wild boar was domesticated as early as 13,000 BC in the Tigris River basin...

, its ancestor the wild boar, and several other wild relatives. Pigs are omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...

s and are highly social and intelligent animals.

Description and behaviour


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
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 at the tip. The snout is used to dig into the soil to find food and is a very acute sense organ. There are four hoof
Hoof
A hoof , plural hooves or hoofs , is the tip of a toe of an ungulate mammal, strengthened by a thick horny covering. The hoof consists of a hard or rubbery sole, and a hard wall formed by a thick nail rolled around the tip of the toe. The weight of the animal is normally borne by both the sole...

ed toes on each foot, with the two larger central toes bearing most of the weight, but the outer two also being used in soft ground.

The dental formula of adult pigs is 3.1.4.3 in each jaw, giving a total of 44 teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

. The rear teeth are adapted for crushing. In the male the canine teeth form tusk
Tusk
Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, wild boar, and walruses, or, in the case of elephants and narwhals, elongated incisors...

s, which grow continuously and are sharpened by constantly being ground against each other.

Distribution



With around 2 billion individuals alive at any time, the domesticated pig is one of the most numerous large mammals on the planet.

The ancestor of the domesticated pig is the wild boar, which is one of the most numerous and widespread large mammals. Its many subspecies are native to all but the harshest climes of continental Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 and its islands and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

 as well, from Ireland and India to Japan and north to Siberia. Although it has been exterminated in some areas, its numbers are stable or even increasing rapidly, in most of its native range.

Long isolated from other pigs on the many islands of Indonesia, Malaysia, and the Philippines, pigs have evolved into many different species, including wild boar, bearded pigs, and warty pigs. Humans have introduced pigs into Australia, North and South America, and numerous islands, either accidentally as escaped domestic pigs which have gone feral
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...

, or as wild boar. These have typically adapted well, and are increasing in number and broadening their range outside human control.

Diet and foraging


Pigs are omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...

s, which means that they consume both plants and animals. In the wild, they are foraging animals, primarily eating leaves, grasses, roots, fruits and flowers. In confinement pigs are fed mostly corn and soybean meal with a mixture of vitamins and minerals added to the diet.

Relationship with humans


Domesticated pigs
Domestic pig
The domestic pig is a domesticated animal that traces its ancestry to the wild boar, and is considered a subspecies of the wild boar or a distinct species in its own right. It is likely the wild boar was domesticated as early as 13,000 BC in the Tigris River basin...

 are commonly raised as livestock by farmers for meat (generally called pork
Pork
Pork is the culinary name for meat from the domestic pig , which is eaten in many countries. It is one of the most commonly consumed meats worldwide, with evidence of pig husbandry dating back to 5000 BC....

, hams, gammon
Gammon
Gammon may refer to:* Gammon bomb, a type of grenade* Gammon Technical Products, A US Company specializing in aviation fuel quality control and handling equipment* SA-5 Gammon, the NATO designation for the Russian S-200 'Volga' surface-to-air missile system...

 or bacon
Bacon
Bacon is a cured meat prepared from a pig. It is first cured using large quantities of salt, either in a brine or in a dry packing; the result is fresh bacon . Fresh bacon may then be further dried for weeks or months in cold air, boiled, or smoked. Fresh and dried bacon must be cooked before eating...

), as well as for leather
Leather
Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

. Their bristly hair
Hair
Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....

s are also used for brushes. Some breeds of pig, such as the Asian pot-bellied pig
Pot-bellied pig
The pot-bellied pig is a breed of domesticated pig originating in Vietnam.-Description:Considerably smaller than standard American or European farm pigs, most adult pot-bellied pigs are about the size of a medium- or large-breed dog, though their bodies are denser at 8 to 136 kg...

, are kept as pets.

Pigs that are allowed to forage may be watched by swineherd
Swineherd
A swineherd is a person who looks after pigs. The term has fallen out of popular use in favour of pig farmer.-Swineherds in literature:* Hans Christian Andersen wrote a Fairy tale called, "The Swineherd"....

s. Because of their foraging abilities and excellent sense of smell
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...

, they are used to find truffles in many European countries.

Both wild and feral pigs are commonly hunt
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...

ed.

Species


The genus Sus is currently considered to have 10 living species and a number of extinct species known as fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

a:
  • Sus ahoenobarbus - Palawan Bearded Pig
    Palawan Bearded Pig
    The Palawan Bearded Pig is a species of pig endemic to the Philippines, where they can only be found on the archipelago of islands formed by Balabac, Palawan and the Calamian Islands...

     Huet, 1888
  • Extinction
    In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

    Sus australis - Early Pleistocene of China Han, 1987
  • Sus barbatus - Bearded Pig
    Bearded Pig
    The bearded pig , also known as the Bornean bearded pig, is a species of pig. It can be recognized by its prominent beard. It also sometimes has tassels on its tail. It is found in Southeast Asia—Sumatra, Borneo, the Malay Peninsula, and various smaller islands—where it inhabits rainforests and...

     Müller, 1838
  • Sus bijiashanensis - Early Pleistocene of China Han et al, 1975
  • Sus bucculentus - Heude's Pig or Indo-Chinese (or Vietnam) Warty Pig Heude, 1892
  • Sus cebifrons - Visayan Warty Pig
    Visayan warty pig
    The Visayan Warty Pig, Sus cebifrons, is a critically endangered species of pig. The Visayan warty pig is endemic to two of the Visayan Islands in the central Philippines, and is threatened by habitat loss, food shortages and hunting - these are the leading causes of the Visayan Warty Pig's status...

     Heude, 1888
  • Sus celebensis - Celebes Warty Pig
    Celebes Warty Pig
    The Celebes Warty Pig , Sulawesi warty pig or Sulawesi Pig, lives on Sulawesi in Indonesia. It survives in most habitats and can live in altitudes of up to 2,500 metres.- External links :*...

     or Sulawesi Warty Pig Müller & Schlegel, 1843
  • Sus domestica or Sus scrofa domestica - Domestic pig
    Domestic pig
    The domestic pig is a domesticated animal that traces its ancestry to the wild boar, and is considered a subspecies of the wild boar or a distinct species in its own right. It is likely the wild boar was domesticated as early as 13,000 BC in the Tigris River basin...

     Linnaeus, 1758
  • Sus falconeri - Pleistocene of the Siwalik region, India
  • Sus houi - Pleistocene of China Qi et al, 1999
  • Sus hysudricus
  • Sus jiaoshanensis - Early Pleistocene of China Zhao, 1980
  • Sus liuchengensis - Early Pleistocene of China Han, 1987
  • Sus lydekkeri - Pleistocene of China Zdansky
    Otto Zdansky
    Otto A. Zdansky was an Austrian paleontologist.He is best known for his work in China, where he, as an assistant to Johan Gunnar Andersson, discovered a fossil tooth of the Peking Man in 1921 at the Dragon Bone Hill, although he did not disclose it until 1926 when he published it in Nature after...

    , 1928
  • Sus offecinalis - China Koenigswald, 1933
  • Sus oliveri - Oliver's Warty Pig
    Oliver's Warty Pig
    Oliver's Warty Pig , or Mindoro Warty Pig is a small species of pig which can only be found on the island of Mindoro in the Central Philippines. This species previously treated to be a subspecies of S...

     or Mindoro Warty Pig Groves, 1997
  • Sus peii - Early Pleistocene of China Han, 1987
  • Sus philippensis - Philippine Warty Pig
    Philippine Warty Pig
    The Philippine Warty Pig, Sus philippensis, is one of four known pig species endemic to the Philippines. The other three endemic species are the Visayan Warty Pig , Mindoro Warty Pig and the Palawan Bearded Pig , also being rare members of the Suidae family...

     Nehring, 1886
  • Sus scrofa - Wild Boar Linnaeus, 1758
  • Sus subtriquetra - Xue, 1981
  • Sus strozzi
  • Sus verrucosus - Java Warty Pig Müller, 1840
  • Sus xiaozhu - Early Pleistocene of China Han et al, 1975


The Pygmy Hog
Pygmy Hog
Pygmy hog is an endangered species of small wild pig, previously spread across India, Nepal, and Bhutan but now only found in Assam. The current world population is about 150 individuals or fewer...

, formerly Sus salvanius is now placed in the monotypic genus Porcula.

Domestic pigs




Pigs have been domesticated
Domestication
Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been...

 since ancient times
Ancient history
Ancient history is the study of the written past from the beginning of recorded human history to the Early Middle Ages. The span of recorded history is roughly 5,000 years, with Cuneiform script, the oldest discovered form of coherent writing, from the protoliterate period around the 30th century BC...

 in the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....

. Archaeological 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
Near East
The Near East is a geographical term that covers different countries for geographers, archeologists, and historians, on the one hand, and for political scientists, economists, and journalists, on the other...

 in the Tigris Basin. 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. A separate domestication also occurred in China.

In India pigs have been domesticated since a long time mostly in Goa
Goa
Goa , a former Portuguese colony, is India's smallest state by area and the fourth smallest by population. Located in South West India in the region known as the Konkan, it is bounded by the state of Maharashtra to the north, and by Karnataka to the east and south, while the Arabian Sea forms its...

 and some rural areas for pig toilet
Pig toilet
A pig toilet is a simple type of toilet consisting of an outhouse mounted over a pig sty with a chute or hole connecting the two. The pigs consume the faeces of the users of the toilet....

s. This was also done in China (see photo). Though ecologically logical as well as economical, pig toilets are waning in popularity as use of septic tank
Septic tank
A septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations...

s and/or sewerage
Sewerage
Sewerage refers to the infrastructure that conveys sewage. It encompasses receiving drains, manholes, pumping stations, storm overflows, screening chambers, etc. of the sanitary sewer...

 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). With managed rotational grazing techniques pigs can be raised in an environmentally sound manner on pasture much like grazing sheep, goats and cows without high grain inputs.

The domestic pig (Sus scrofa domesticus) is usually given the scientific name
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...

 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 coloured and tend to turn more grayish coloured with age. The upper canines
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...

 form sharp distinctive tusk
Tusk
Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, wild boar, and walruses, or, in the case of elephants and narwhals, elongated incisors...

s that curve outward and upward. Compared to other artiodactyles, their head is relatively long, pointed, and free of wart
Wart
A wart is generally a small, rough growth, typically on a human’s hands or feet but often other locations, that can resemble a cauliflower or a solid blister. They are caused by a viral infection, specifically by human papillomavirus 2 and 7. There are as many as 10 varieties of warts, the most...

s. 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 and can be trained to perform numerous tasks and tricks. Recently, they have enjoyed a measure of popularity as house pets, particularly the dwarf breeds.

Cultural and religious reference to pigs


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

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
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 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. The Invasive Species Specialist Group
IUCN Species Survival Commission
The IUCN Species Survival Commission is a special commission operated by the International Union for Conservation of Nature. The commission's "major role is to provide information to IUCN on biodiversity conservation, the inherent value of species, their role in ecosystem health and functioning,...

 lists feral pigs on the list of the world's 100 worst invasive species and says:


Health issues


Pigs can harbour a range of parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

s and diseases that can be transmitted to humans. These include trichinosis
Trichinosis
Trichinosis, also called trichinellosis, or trichiniasis, is a parasitic disease caused by eating raw or undercooked pork or wild game infected with the larvae of a species of roundworm Trichinella spiralis, commonly called the trichina worm. There are eight Trichinella species; five are...

, Taenia solium
Pork tapeworm
Taenia solium, also called the pork tapeworm, is a cyclophyllid cestode in the family Taeniidae. It infects pigs and humans in Asia, Africa, South America, parts of Southern Europe and pockets of North America. In the larval stage, it causes cysticercosis which is a major cause of seizures in...

, cysticercosis
Cysticercosis
Cysticercosis refers to tissue infection after exposure to eggs of Taenia solium, the pork tapeworm. The disease is spread via the fecal-oral route through contaminated food and water, and is primarily a food borne disease. After ingestion the eggs pass through the lumen of the intestine into the...

, and brucellosis
Brucellosis
Brucellosis, also called Bang's disease, Crimean fever, Gibraltar fever, Malta fever, Maltese fever, Mediterranean fever, rock fever, or undulant fever, is a highly contagious zoonosis caused by ingestion of unsterilized milk or meat from infected animals or close contact with their secretions...

. Pigs are also known to host large concentrations of parasitic ascarid
Ascaris
Ascaris is a genus of parasitic nematode worms known as the "giant intestinal roundworms". One species, A. suum, typically infects pigs, while another, A. lumbricoides, affects human populations, typically in sub-tropical and tropical areas with poor sanitation. A...

 worms in their digestive tract. The presence of these diseases and parasites is one reason pork meat should always be well cooked or cured before eating. Today, trichinellosis infections from eating pork are relatively uncommon, at least in the United States, due to more stringent health laws, better refrigeration, and public awareness of the dangers of eating undercooked meat. Some religious groups that consider pork unclean refer to these issues as support for their views.

Pigs are susceptible to bronchitis
Bronchitis
Acute bronchitis is an inflammation of the large bronchi in the lungs that is usually caused by viruses or bacteria and may last several days or weeks. Characteristic symptoms include cough, sputum production, and shortness of breath and wheezing related to the obstruction of the inflamed airways...

 and pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...

. They have small lungs in relation to body size; for this reason, bronchitis or pneumonia can kill a pig quickly. There is concern that pigs may allow animal viruses such as influenza
Influenza
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...

 or Ebola Reston
Ebola Reston
- Introduction and Use of Term :The species Reston ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Reston virus . The members of the species are called Reston ebolaviruses...

 to infect humans more easily. Some strains of influenza are endemic
Endemic (epidemiology)
In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. For example, chickenpox is endemic in the UK, but malaria is not...

 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.

See also


  • Babirusa
    Babirusa
    The North Sulawesi babirusa, Babyrousa celebensis, is a pig-like animal native to northern Sulawesi and the nearby Lembeh Islands in Indonesia. It has two pairs of large tusks composed of enlarged canine teeth. The canines in the maxilla penetrate the top of the snout, curving back toward the...

  • Fetal pig
    Fetal pig
    Fetal pigs are unborn pigs used in elementary as well as advanced biology classes as objects for dissection. Pigs, as a mammalian species, provide a good specimen for the study of physiological systems and processes.-Use in biology labs:...

  • Hog-baiting
    Hog-baiting
    Hog-baiting, also known as, hog dogging, is a spectator event that simulates wild boar hunting with dogs. It requires specially bred "hog dogs" that are used to bay a hog or boar...

  • List of fictional pigs
  • List of pigs
  • Pig Olympics
    Pig Olympics
    The Pig Olympics are a sporting events for specially bred and trained piglets, and include pigball , swimming, and running . The competition is organized by the Sport-Pig Federation, which claims over 100 members....

  • Pot-bellied pig
    Pot-bellied pig
    The pot-bellied pig is a breed of domesticated pig originating in Vietnam.-Description:Considerably smaller than standard American or European farm pigs, most adult pot-bellied pigs are about the size of a medium- or large-breed dog, though their bodies are denser at 8 to 136 kg...



External links