Wild Pigs of the World

At present, 17 extant species of pig are recognized in the family Suidae, although the taxonomy of some taxa requires further work, especially in the Philippines. Even without additional species this is a species-rich Family, reflecting the evolutionary success, ecological versatility, and considering their endemic presence on a great number of islands, the extensive dispersal ability of pigs. Some of these species are highly threatened with very few remaining animals in the wild.

Common Warthog. Photo credits, Jeffrey Graham

Most people with even the smallest amount of taxonomic knowledge can readily identify any of the many suid species as pigs, with the snout disc being a giveaway. This morphological adaptation is related to rooting in the soil, which is exactly what other, generally less known species with similar features such as aardvarks and coatis use it for. Pigs are small to medium animals, varying in size between 58–66 cm in length, and 6–9 kg in weight in the case of the Pygmy Hog (Porcula salvania), to 130–210 cm and 130–275 kg in the Forest Hog (Hylochoerus meinertzhageni). They have large heads and short necks, with relatively small eyes and prominent ears. Suids are typically stockily built, have a bristly coat, and a short tail ending in a tassel.

Pigs and hogs occur in a great range of environments, from dense tropical rainforests in South-east Asia and Africa, to dry, open woodlands, grassland, and deserts. They survive in the icy colds of Siberia, but also thrive in hot areas. In fact, there seem to be few ecological conditions that pigs cannot cope with. 

In general Suidae are social animals. Females often live in large, natal family groups, and males tend to be solitary or monopolize a group of females. The Suidae are the only ungulates to commonly produce large litters of offspring; litters of 1–6 are normal, and some species, such as S. scrofa, may have up to 13 infants at a time. Infants of most species (all genera with the exception of Babyrousa, Hylochoerus, and Phacochoerus) are marked with horizontal stripes, which provide camouflage in forested environments.

Among broad mammal groups, pigs are usually rated 4th in overall intelligence, behind great apes, dolphins and elephants. They have sophisticated learning and problem solving abilities, and their intelligence has been likened to that of a 3 year-old human child.

With about two billion domestic pigs in the world, it is clear that the Suidae are an important component of our present day societies. Pigs and humans and their ancestors have probably closely interacted for much of their evolution. The cultural and economic role of domesticated pigs is significant in many parts of the world. Pigs are an integral part of the diets of humans in numerous cultures, and feature in other cultures as popular pets. Pigs mature faster than other domesticated ungulates, have larger litters, and can feed on human garbage, making them efficient and valuable parts of many agricultural systems.