Pig. The pig, often called swine, hog, or domestic pig when distinguishing from other members of the genus Sus, is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of Sus scrofa or a distinct species. The pig's head-plus-body length ranges from 0.9 to 1.8 m, and adult pigs typically weigh between 50 and 350 kg, with well-fed individuals even exceeding this range. The size and weight of hogs largely depends on their breed. Compared to other artiodactyls, a pig's head is relatively long and pointed. Most even-toed ungulates are herbivorous, but pigs are omnivores, like their wild relative. Pigs grunt and make snorting sounds. When used as livestock, pigs are farmed primarily for the production of meat, called pork. A group of pigs is called a passel, a team, or a sounder. The animal's bones, hide, and bristles are also used in products. Pigs, especially miniature breeds, are kept as pets. Skull Skeleton Bones of the foot The pig typically has a large head, with a long snout which is strengthened by a special prenasal bone and a disk of cartilage at the tip. The snout is used to dig into the soil to find food and is a very acute sense organ. The dental formula of adult pigs is, giving a total of 44 teeth. The rear teeth are adapted for crushing. In the male, the canine teeth can form tusks, which grow continuously and are sharpened by constantly being ground against each other. Four hoofed toes are on each foot, with the two larger central toes bearing most of the weight, but the outer two also being used in soft ground. Most pigs have rather a bristled sparse hair covering on their skin, although woolly-coated breeds such as the Mangalitsa exist. Pigs possess both apocrine and eccrine sweat glands, although the latter appear limited to the snout and dorsonasal areas. Pigs, however, like other hairless mammals, do not use thermal sweat glands in cooling. Pigs are also less able than many other mammals to dissipate heat from wet mucous membranes in the mouth through panting. Their thermoneutral zone is 16 to 22 °C. At higher temperatures, pigs lose heat by wallowing in mud or water via evaporative cooling, although it has been suggested that wallowing may serve other functions, such as protection from sunburn, ecto-parasite control, and scent-marking. Pigs are one of four known mammalian species which possess mutations in the nicotinic acetylcholine receptor that protect against snake venom. Mongooses, honey badgers, hedgehogs, and pigs all have modifications to the receptor pocket which prevents the snake venom-neurotoxin from binding. These represent four separate, independent mutations. Pigs have small lungs in relation to their body size, and are thus more susceptible than other domesticated animals to fatal bronchitis and pneumonia. Pigs have a maximum life span of about 27 years. The genome of the pig has been sequenced and contains about 22,342 protein-coding genes. The pig is most often considered to be a subspecies of the wild boar, which was given the name Sus scrofa by Carl Linnaeus in 1758; following from this, the formal name of the pig is Sus scrofa domesticus. However, in 1777, Johann Christian Polycarp Erxleben classified the pig as a separate species from the wild boar. He gave it the name Sus domesticus, which is still used by some taxonomists. The American Society of Mammalogists considers it a separate species. Remains of pigs have been dated to earlier than 11,400 years ago in Cyprus. Those animals must have been introduced from the mainland, which suggests domestication in the adjacent mainland by then. Pigs were separately domesticated in China beginning 8,000 years ago, and have been one of the most important domesticated animals there ever since. In the Near East, pig husbandry spread for the next few millennia. It reduced gradually during the Bronze Age, as rural populations focused instead on commodity-producing livestock. It was sustained in urbanized regions, however. DNA evidence from subfossil remains of teeth and jawbones of Neolithic pigs shows that the first domestic pigs in Europe had been brought from the Near East. This stimulated the domestication of local European wild boar, resulting in a third domestication event with the Near Eastern genes dying out in European pig stock.