With its stubby snout, thick body, short legs, and kinked tail, the pig is found on all continents except for Antarctica. These animals do well in captivity, and they often thrive in the wild, living in forests, swamps, and shrub lands.
Pigs have large heads with a snout for a nose. They have four toes on every hoof, but they only walk on the two front toes, giving them the appearance of walking on their tiptoes. Many species, especially wild pigs, have large tusks that are used for defense and for rooting in the dirt. However, many breeds of domestic pigs have been selectively bred to be without tusks. Pigs can be pink, white, brown, black, and spotted.
Female pigs (sows) are ready to breed when they are about nine months old. After mating with the male pig (boar), a sow will be pregnant for about four months. She will give birth to a litter of 6 to 10 piglets. They will drink milk from their mother for about eight weeks before weaning.
Pigs are one of the most intelligent forms of livestock. Pigs are quick on their feet and are excellent swimmers. When raised in the right conditions, pigs are very clean, calm animals. Pigs eat almost anything, including grain, food scraps, meat, insects, tree bark, plants, nuts, and fruits. In the wild, pigs are scavengers. Pigs are one of the few animals that chew their food completely in the same manner that humans do. Pigs have a distinctive social order, and they establish hierarchies in their herds. Because pigs have no sweat glands on their bodies, to keep cool, they wallow in the mud.
The oldest form of livestock, pigs were tamed from wild swine in China as early as 5000 BC. Because pigs consume an omnivorous diet, they were easier to care for than other livestock animals like cattle and chickens.
The wild form of the domestic pig is known as the wild boar, and is native to Europe, Asia, and Africa. Wild boar were introduced into America as game animals for hunting in the 19th century, but early Spanish explorers like DeSoto brought domestic pigs to North America from Europe. Often, these pigs would escape captivity and become feral. These feral pigs are informally known as wild hogs or "razorbacks", due to their spiky fur. These animals have become a nuisance in the United States, causing damage to property and crops.
Pigs are farmed commercially all across the globe in industrialized nations, and they live in the wild in many places, too. In many developing nations, pigs are raised in a more natural manner, living outdoors in open fields. In some cases, they are even watched over by shepherds.