Suines are members of the biological suborder Suina, which includes two living and four extinct families — pigs (19 species), peccaries (4 species), raoellids (sister group to cetaceans, extinct), entelodonts (true omnivores with bony jaws, extinct), choeropotamids (an old Eocene family), and sanitherids (another old group). Suborder Suina is is one of three in order Artiodactyla, the even-toed ungulates. The other suborders are Tylopoda (hippos and camelids) and Ruminantia (deer, giraffes, cattle, goats, sheep, antelope, okapi, mouse deer, musk deer, and chevrotains). The closest living relatives of the even-toed ungulates are the cetaceans (dolphins, whales, and porpoises). These orders split from each other approximately 60 million years ago, in the early Paleogene. Suines are colloquially known as swine.
As the suborder that includes pigs, Suina is one of the most economically important mammalian suborders to humans, due to the membership of the Domestic Pig, also the most intelligent member of Suina. There are approximately 2 billion domestic pigs worldwide, greater than the number of cats and dogs combined. The Domestic Pig is actually a subspecies of the Wild Boar, from which it was domesticated in 5,000 – 7,000 years ago. The natural range of the Wild Boar covers most of the mid and low latitudes of Eurasia and northern Africa. Unlike the pink coloration of the Domestic Pig, boars are brown and may display stripes.
Members of suborder Suina are considered among the most archaic and primitive of even-toed ungulates. They may be the oldest suborder of even-toed ungulates. This is indicated by anatomical features, such as the absence of maxillary teeth, making chewing impossible. Instead, suines gulp down their food in big chunks. They are known for being truly omnivorous, like rodents, and will happily consume garbage or food scraps, which has given them a reputation for gluttony and filthiness. Despite their negative qualities, it should be noted that pigs are among the most intelligent animals kept by humans in factory farms. In recent years, propositions to improve the living conditions of pigs have appeared on ballots worldwide.
The least familiar member of Suina is the peccary, a small swine that lives in southwestern North America and throughout Central and South America. Peccaries are distinct from pigs in that they originated in South America when it was an island continent, rather than Afro-Eurasia. Peccaries and pigs can be told apart by their short and straight (rather than curved) tusks. Unlike pigs, peccaries are never known to have been domesticated, though they are hunted for meat.