Among all our farm animals they are ranked most intelligent. Many millions of years ago there were various types of pigs and pig- like animals whose bones are found fossilized in rocks today. They ranged in size from species like our little American peccary up to beasts as large as a bison. Among them are fossil swine very similar to our barnyard pig. It has undergone less change over the ages than any other domestic animal.
All pigs have much in common.
The snout with its tough flexible disk- like tip is the most prominent feature of all species. It is a combination steam shovel and bulldozer for digging, pushing and lifting. A pig's bristles give little protection against cold and, with no sweat glands in the skin, they suffer from heat. Most wild swine, therefore, are inhabitants of swamps and forests in warm and temperate regions. Commonly they run in herds called sounders.