Juvenile pigs are known as piglets.[2] Pigs live in complex social groups and are considered one of the more intelligent mammals, as reflected in their ability to learn.[3]
With around 1 billion of this species alive at any time, the domestic pig is among the most populous large mammals in the world.[4][5] Pigs areomnivores and can consume a wide range of food.[6] Pigs are biologically similar to humans and are thusfrequently used for human medical research.[7]
TheOnline Etymology Dictionary provides anecdotal evidence as well as linguistic, saying that the term derives
probably from Old English*picg, found in compounds, ultimate origin unknown. Originally "young pig" (the word for adults wasswine). Apparently related toLow Germanbigge,Dutchbig ("but the phonology is difficult" --OED). ... Another Old English word for "pig" wasfearh, related tofurh "furrow," fromPIE *perk- "dig, furrow" (source also of Latinporc-us "pig," seepork). "This reflects a widespreadIE tendency to name animals from typical attributes or activities" [Roger Lass]. Synonymsgrunter,oinker are from sailors' and fishermen's euphemistic avoidance of uttering the word pig at sea, a superstition perhaps based on the fate of theGadarene swine, who drowned.[8]
TheOnline Etymology Dictionary also traces the evolution ofsow, the term for a female pig, through various historical languages:
An adjectival form isporcine. Anotheradjectival form (technically for the subfamily rather than genus name) issuine (comparable tobovine,canine, etc.); for the family, it issuid (as withbovid,canid).[10]
A typical pig has a large head with a long snout that is strengthened by a special prenasal bone and by a disk ofcartilage at the tip.[11] The snout is used to dig into the soil to find food and is a very acute sense organ. Each foot has four hooves with the two larger central toes bearing most of the weight, and the outer two also being used in soft ground.[12]
Thedental formula of adult pigs is3.1.4.33.1.4.3, giving a total of 44teeth. The rear teeth are adapted for crushing. In the male, the canine teeth formtusks, which grow continuously and are sharpened by constantly being ground against each other.[11]
Occasionally, captive mother pigs maysavage their own piglets, often if they become severely stressed.[13] Some attacks on newborn piglets are non-fatal. Others may kill the piglets and sometimes, the mother may eat them. An estimated 50% of piglet fatalities are due to the mother attacking, or unintentionally crushing, the newborn pre-weaned animals.[14]
With around 1 billion individuals alive at any time, thedomestic pig is one of the most numerous large mammals on the planet.[4][5]
The ancestor of the domestic pig is thewild boar, which is one of the most numerous and widespread large mammals. Its many subspecies are native to all but the harshest climates of continentalEurasia and its islands andAfrica as well, from Ireland and India to Japan and north to Siberia.
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 goneferal, or as wild boar.
The wild boar (Sus scrofa) can take advantage of any forage resources. Therefore, they can live in virtually any productive habitat that can provide enough water to sustain large mammals such as pigs. Pigs are famously fecund; when well-fed, a sow can birth twelve or more piglets in her annual litter. If there is increased foraging by wild boars in certain areas, they can cause a nutritional shortage which can cause the pig population to decrease. If the nutritional state returns to normal, the pig population will most likely rise due to the pigs' naturally-increased reproduction rate.[15]
Pigs areomnivores, which means that they consume both plants and animals. In the wild, they areforagers, searching through their habitat for food (which, for pigs, often includes digging with their snouts). Wild pigs eat roots, tubers, leaves, fruits, mushrooms, and flowers, in addition to some insects (especially insect grubs) and fish. Pigs are famously fond oftruffle mushrooms, which grow underground; pigs find them by scent and unearth them with their snouts. InEurope, trained "truffle pigs" find these valuable fungi for humans. Pigs do not hunt, but will readily eat carrion, eggs, and other animal foods that they can find. As livestock, pigs were once fed all manner of mixed household food scraps (called "slops"), but on large modern farms are now fed mostlycorn andsoybean meal[16] with a mixture of vitamins and minerals added. Traditionally, pigs were raised on dairy farms and fed any excess milk and thewhey left over from cheese and butter making. Pigs brought so much extra income to these farms that they earned the nickname "mortgage lifters".[17] Older pigs will consume three to five gallons of water per day.[18] When kept as pets, the optimal healthy diet consists mainly of a balanced diet of raw vegetables, although some may give their pigs commercialmini pig pellet feed.[19]
Most pigs today aredomesticated pigs raised for meat (known aspork).Miniature breeds are commonly kept as pets.[19] Because of their foraging abilities and excellentsense of smell, people in many European countries use them to findtruffles. Both wild andferal pigs are commonlyhunted.
Apart from meat, pig skin is turned intoleather, and theirhairs are used to make brushes. The relatively short, stiff, coarse pig hairs are calledbristles, and were once so commonly used inpaintbrushes that in 1946 theAustralian Government launchedOperation Pig Bristle. In May 1946, in response to a shortage of pig bristles for paintbrushes to paint houses in the post-World War II construction boom, theRoyal Australian Air Force (RAAF) flew in 28short tons of pig bristles from China, their only commercially available source at the time.[20]
Human skin is very similar to pig skin, therefore many preclinical studies employ pig skin.[21][22] In addition to providing use in biomedical research[21][22] and for drug testing,[23] genetic advances in human healthcare have provided a pathway for domestic pigs to becomexenotransplantation candidates for humans.[24]
Pigs have beendomesticated sinceancient times in theOld World. Pigs were domesticated on each end of Eurasia, and possibly several times.[26] It is now thought that pigs were attracted to human settlements for the food scraps, and that the process of domestication began as a commensal relationship.[27] 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 13,000–12,700BP in theNear East in the Tigris Basin,[28]Çayönü,Cafer Höyük,Nevalı Çori.[29] 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.[30]
Pigs were also domesticated in China, potentially more than once.[31] In some parts of China pigs were kept in pens from early times, separating them from wild populations and allowing farmers to create breeds that were fatter and bred more quickly.[32] Early Modern Europeans brought these breeds back home and crossed them with their own pigs, which was the origins of most modern pig breeds.[33]
In India, pigs have been domesticated for a long time mostly inGoa and somerural areas forpig toilets. This practice also occurred in China. Though ecologically logical as well as economical, pig toilets are waning in popularity as use ofseptic tanks and/orsewerage systems is increasing in rural areas.
Hernando de Soto and other early Spanish explorers brought pigs to southeastern North America from Europe. As in medieval Europe, pigs are valued on certain oceanic islands for their self-sufficiency, which allows them to be turned loose, although the practice does have drawbacks (seeenvironmental impact).
The domestic pig (Sus domesticus) is usually given thescientific nameSus scrofa domesticus, although some taxonomists, including theAmerican Society of Mammalogists, call itS. domesticus, reservingS. scrofa for thewild boar. It was domesticated approximately 5,000 to 7,000 years ago. The uppercanines form sharp distinctivetusks that curve outward and upward. Compared to other artiodactyles, their head is relatively long, pointed, and free ofwarts. Their head and body length ranges from 0.9 to 1.8 m (35 to 71 in) and they can weigh between 50 and 350 kg (110 and 770 lb).
In November 2012, scientists managed tosequence the genome of thedomestic pig. The similarities between the pig and human genomes mean that the new data may have wide applications in the study and treatment of human genetic diseases.[34][35][36]
In August 2015, a study looked at over 100 pig genome sequences to ascertain their process of domestication. The process of domestication was assumed to have been initiated by humans, involved few individuals and relied on reproductive isolation between wild and domestic forms. The study found that the assumption of reproductive isolation with population bottlenecks was not supported. The study indicated that pigs were domesticated separately in Western Asia and China, with Western Asian pigs introduced into Europe where they crossed with wild boar. A model that fitted the data included admixture with a now extinctghost population of wild pigs during thePleistocene. The study also found that despite back-crossing with wild pigs, the genomes of domestic pigs have strong signatures of selection at DNA loci that affect behavior and morphology. The study concluded that human selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars and createddomestication islands in the genome. The same process may also apply to other domesticated animals.[37][38]
Pigs have been important in culture across the world sinceNeolithic times. They appear inart, literature, andreligion. In Asia thewild boar is one of 12 animal images comprisingthe Chinese zodiac, while in Europe the boar represents a standard charge inheraldry. InIslam andJudaism pigs and those who handle them are viewed negatively, and the consumption of pork is forbidden.[39][40] Pigs are alluded to inanimal epithets andproverbs.[41][42] The pig has been celebrated throughout Europe since ancient times in itscarnivals, the name coming from the Italiancarne levare, the lifting of meat.[43]
Pigs have been brought into literature for varying reasons, ranging from the pleasures of eating, as inCharles Lamb'sA Dissertation upon Roast Pig, toWilliam Golding'sLord of the Flies (with the fat character "Piggy"), where the rotting boar's head on a stick representsBeelzebub, "lord of the flies" being the direct translation of the Hebrewבעל זבוב, andGeorge Orwell'sallegorical novelAnimal Farm, where the central characters, representingSoviet leaders, are all pigs.[44][45][46][43]
Domestic pigs that have escaped from urban areas 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 analien 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.[11] TheInvasive Species Specialist Group lists feral pigs on thelist of the world's 100 worst invasive species and says:[47]
Feral pigs like other introduced mammals are major drivers of extinction and ecosystem change. They have been introduced into many parts of the world, and will damage crops and home gardens as well as potentially spreading disease. They uproot large areas of land, eliminating native vegetation and spreading weeds. This results in habitat alteration, a change in plant succession and composition and a decrease in native fauna dependent on the original habitat.
Because of their biological similarities, pigs can harbour a range ofparasites and diseases that can be transmitted to humans. Examples of suchzoonoses includetrichinosis,Taenia solium,cysticercosis, andbrucellosis. Pigs also host large concentrations of parasiticascarid worms in their digestive tracts.[48]
^abHerron, Alan J. (5 December 2009)."Pigs as Dermatologic Models of Human Skin Disease"(PDF).Ivis. American College of Veterinary Pathologists. DVM Center for Comparative Medicine and Department of Pathology Baylor College of Medicine Houston, Texas. Retrieved27 January 2018.pig skin has been shown to be the most similar to human skin. Pig skin is structurally similar to human epidermal thickness and dermal-epidermal thickness ratios. Pigs and humans have similar hair follicle and blood vessel patterns in the skin. Biochemically pigs contain dermal collagen and elastic content that is more similar to humans than other laboratory animals. Finally pigs have similar physical and molecular responses to various growth factors.
^Funk, Stephan M.; Verma, Sunil Kumar; Larson, Greger; Prasad, Kasturi; Singh, Lalji; Narayan, Goutam; Fa, Julia E. (November 2007). "The pygmy hog is a unique genus: 19th century taxonomists got it right first time round".Molecular Phylogenetics and Evolution.45 (2):427–436.Bibcode:2007MolPE..45..427F.doi:10.1016/j.ympev.2007.08.007.PMID17905601.
^White, Sam (2011). "From Globalized Pig Breeds to Capitalist Pigs: A Study in Animal Cultures and Evolutionary History".Environmental History.16 (1):94–120.doi:10.1093/envhis/emq143.
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