[2] Studies based on biochemistry and DNA hybridization suggest they are domesticated animals that do not exist naturally in the wild, but are descendants of a closely related cavy species such as C. tschudii.

Their docile nature, friendly responsiveness to handling and feeding, and the relative ease of caring for them have continued to make guinea pigs a popular choice of household pets.

[16] These claims are supported by archaeological digs and transcribed Quechua mythology,[17] providing evidence that sacrificial rituals involving guinea pigs served many purposes in society such as appeasing the gods, accompanying the dead, or reading the future.

[19]In the early 1500s, Spanish, Dutch, and English traders took guinea pigs to Europe, where they quickly became popular as exotic pets among the upper classes and royalty, including Queen Elizabeth I.

The German word for them is Meerschweinchen, literally "little sea pig", in Polish they are called świnka morska, in Hungarian as tengerimalac, and in Russian: морская свинка, romanized: morskaya svinka.

For example, sailing ships stopping to reprovision in the New World would pick up guinea pig stores, providing an easily transportable source of fresh meat.

[39] In the 1990s, a minority scientific opinion emerged proposing that caviomorphs such as guinea pigs, chinchillas, and degus are not actually rodents, and should be reclassified as a separate order of mammals (similar to the rodent-like lagomorphs which includes rabbits and hares).

[40][41][42] Subsequent research using wider sampling restored the consensus among mammalian biologists regarding the current classification of rodents, including guinea pigs, as monophyletic.

They are social animals, living in the wild in small groups ("herds") that consist of several females ("sows"), a male ("boar"), and their young ("pups" not "piglets", a break with the preceding porcine nomenclature).

Large litters result in higher incidences of stillbirth, but because the pups are delivered at an advanced stage of development, lack of access to the mother's milk has little effect on the mortality rate of newborns.

Signs of toxemia include anorexia (loss of appetite), lack of energy, excessive salivation, a sweet or fruity breath odor due to ketones, and seizures in advanced cases.

[78] Females that do not give birth may develop an irreversible fusing or calcified cartilage of the pubic symphysis, a joint in the pelvis, which may occur after six months of age.

[citation needed] Wire mesh floors can cause injury and may be associated with an infection commonly known as bumblefoot (ulcerative pododermatitis),[80] so cages with solid bottoms, where the animal walks directly on the bedding, are typically used.

Large cages allow for adequate running space and can be constructed from wire grid panels and plastic sheeting, a style known as C&C, or "cubes and coroplast".

[82] Guinea pigs tend to be messy; they often jump into their food bowls or kick bedding and feces into them, and their urine sometimes crystallizes on cage surfaces, making it difficult to remove.

Some pet owners and veterinary organizations have advised that, as a legume rather than a grass hay, alfalfa consumed in large amounts may lead to obesity, as well as bladder stones from the excess calcium in all animals except for pregnant and very young guinea pigs.

[97] Healthy diets for guinea pigs require a complex balance of calcium, magnesium, phosphorus, potassium, and hydrogen ions; but adequate amounts of vitamins A, D, and E are also necessary.

[51] A constant supply of hay is generally recommended, as guinea pigs feed continuously and may develop bad habits if food is not present, such as chewing on their hair.

[106] Mange mites (Trixacarus caviae) are a common cause of hair loss, and other symptoms may also include excessive scratching, unusually aggressive behavior when touched (due to pain), and, in some instances, seizures.

[114] Guinea pigs are prey animals whose survival instinct is to mask pain and signs of illness, and many times, health problems may not be apparent until a condition is severe or in its advanced stages.

Treatment of disease is made more difficult by the extreme sensitivity guinea pigs have to most antibiotics, including penicillin, which kill off the intestinal flora and quickly bring on episodes of diarrhea and in some cases, death.

[medical citation needed] Folklore traditions involving guinea pigs are numerous; they are exchanged as gifts, used in customary social and religious ceremonies, and frequently referred to in spoken metaphors.

The animal is so entrenched in the culture that one famous painting of the Last Supper in the main cathedral in Cusco shows Christ and his disciples dining on guinea pig.

[137] The Fairy Caravan, a novel by Beatrix Potter,[138] and Michael Bond's Olga da Polga series for children,[139] both feature guinea pigs as the protagonist.

Both rural and urban families raise guinea pigs for supplementary income, and the animals are commonly bought and sold at local markets and large-scale municipal fairs.

[152][36] In the 1990s and 2000s, La Molina University began exporting large-breed guinea pigs to Europe, Japan, and the United States in the hope of increasing human consumption outside of countries in northern South America.

[8] Efforts have been made to promote guinea pig husbandry in developing countries of West Africa,[148] where they occur more widely than generally known because they are usually not covered by livestock statistics.

[161] Subsequent university efforts have sought to change breeding and husbandry procedures in South America to make the raising of guinea pigs as livestock more economically sustainable.

[165] Guinea pigs played a major role in the establishment of germ theory in the late 19th century, through the experiments of Louis Pasteur, Émile Roux, and Robert Koch.

This is in part because research into the genetics of guinea pigs has lagged behind that of other rodents, although geneticists W. E. Castle and Sewall Wright made some contributions to this area of study, especially regarding coat color.