The name “guinea pig” is confusing, leading many to wonder if this small, tailless creature is related to the large livestock animal. The answer is a definitive “no,” as the two animals exist in completely separate branches of the mammalian family tree. This discrepancy is a result of historical misidentification and linguistic evolution. Examining their scientific classification and historical naming conventions clarifies the significant gulf between these species.
Scientific Classification of Both Species
The most direct way to prove that the guinea pig and the true pig are unrelated is by examining their scientific classification. The guinea pig, or Cavia porcellus, is a member of the Order Rodentia, making it a rodent, like mice and squirrels. Specifically, it belongs to the Family Caviidae, a group of South American rodents known as cavies.
The true pig, such as the domestic pig (Sus scrofa domesticus), belongs to the Order Artiodactyla, or the even-toed ungulates. This order includes other hoofed animals like deer, cattle, and hippopotamuses. The pig’s specific classification falls under the Family Suidae, the swine. The only classification level these two animals share is the Class Mammalia, which includes all animals with fur and that nurse their young.
The Origin of the Name “Guinea Pig”
The common name resulted from two separate historical accidents, one for each word. The “pig” component likely originates from observations European traders made when the animals were imported from South America in the 16th century. The guinea pig’s short, stout body and lack of a tail may have reminded people of small swine. Also, their high-pitched squeals and grunts are similar to those of a pig. This association is reflected in their scientific name, Cavia porcellus, where porcellus is Latin for “little pig.”
The “guinea” part of the name is less certain but has several theories. It may reference the price, as the animal may have been sold for one guinea coin in 16th-century England. A geographical explanation suggests the name is a corruption of “Guiana,” a region in South America where some specimens originated. Another theory is that the animals were shipped through ports in Guinea, West Africa, or that “Guinea” was used as a general term for any distant or foreign land.
Key Anatomical and Behavioral Differences
Beyond classification, their physical biology and habits highlight their distinct evolutionary paths. The guinea pig is a strict herbivore that relies on a specialized digestive system, including a large cecum, to process tough plant fiber. As a rodent, it possesses a single pair of chisel-like incisors in both the upper and lower jaw that grow continuously throughout its life.
In contrast, the true pig is an omnivore with a generalized digestive tract capable of processing both plants and meat. Pigs are large, hoofed ungulates with a distinct snout, while guinea pigs are small, compact rodents. The physical structure and dietary needs of these two animals confirm they are biologically separate, and their shared name is purely a quirk of history.