Wild (feral) pigs and domestic pigs are actually Eurasian wild hogs.

Feral pigs generally occupy wooded habitats, and live in herds of at least 20 individuals, consisting of several mother and young groups; adult males are typically solitary.

The coat of feral pigs is usually blackish and coarser than that of domestic pigs.

Also, feral pigs are thinner, more streamlined in body shape, and have longer, sharper tusks than domestic counterparts.

Domestication of pigs began about 8,500-9,000 years ago, with the Eurasian wild pigs in Asia.

Domestic pigs of Eurasian wild pig stock were introduced into the New World and the United States several times over the past centuries.

Initially, the Polynesians brought pigs into Hawaii about 1,000 years ago. Later, Christopher Columbus introduced pigs to the West Indies in 1493, and Hernando de Soto brought the species to Florida in 1539.

Expeditions led by both Francisco Coronado from Mexico City in 1540 and de Soto from Florida in 1541 into Arkansas, Texas, and other states, relied on pigs as food.

These pigs often escaped or were stolen by Native Americans and released to form free-ranging populations.

From the 1700s until the mid-20th century, Europeans feral pigs were introduced into various Midwestern states.

Until the mid-20th century, pigs often ranged freely in woodlots surrounding many towns and villages.

When this practice became illegal, many free-ranging pigs were unclaimed and became feral.

European wild pigs were introduced into a shooting preserve in North Carolina in 1912.

During the 1920s and 1930s, most of these wild pigs escaped and dispersed into other areas of the Appalachians.

In addition, feral pigs were trapped and transferred for sport hunting in the southeastern United States, thereby expanding the range of this species.

Today, feral pig populations occur in four major locations in the United States: southeastern United States, California, eight islands in Hawaii, and Puerto Rico/Virgin Islands.

Prior to 1981, the range of feral pigs in the lower 48 states was confined to 15 states, ranging from California eastward to Virginia.

Today, however, pigs have become established in eight additional states, extending from Colorado eastward to Ohio and West Virginia.

Anecdotal evidence also suggests that wild pigs might occur in south central Pennsylvania.

In fact, who is the famous pig actor that trains in karate and lives in southern Pennsylvania? - Pork Chop.

The most plausible explanation for range expansion of wild pigs is clandestine trap-and-transfer of feral pigs for hunting purposes.

Feral hogs illegally transported in livestock trailers to release sites are often very difficult to distinguish from hogs being shipped to production or slaughter facilities, thereby making it hard to monitor and control this practice.

Recent expansions also can be attributed to animals that dispersed from established populations, escaped from properties owned by hunting clubs for sport hunting, or escaped from domestic swine producers and pet owners.

Wildlife biologists are in general agreement that feral pigs have been detrimental to native fauna and flora.

Feral pigs may have direct negative effects on other wildlife by feeding on small vertebrates, e.g., frogs, snakes, and salamanders, and on nests of ground-nesting birds.

Pigs can also compete with native wildlife, e.g., deer and turkey, for acorn crops in the fall.

Feral pigs may have indirect negative impacts on native fauna and flora in forests.

The foraging activity of pigs, e.g., uprooting and digging in the soil, can reduce the diversity and abundance of soil arthropods, which are vital to the health of a forest ecosystem.

In some areas, like Great Smoky Mountains National Park, foraging feral pigs consume and trample seedlings and herbaceous vegetation (e.g., wildflowers).

Feral pigs can cause problems for the agricultural industry.

For example, feral male pigs occasionally break into pens of domestic pigs, breeding with the females and injuring the males.

Foraging by pigs can severely damage agricultural crops.

In addition, fatal diseases, such as brucellosis and trichinosis, can be transmitted from feral pigs to domestic pigs and to other livestock and humans.

In conclusion, the pig in its domestic form is one of the most important sources of food for humans worldwide, but the feral pig is a classic example of an exotic species that has "ecologically backfired."