There are many brees of Guinea pig which have been developed since its domestic ca. 5000 BC. Breeds vary widely in appearance and purpose, ranging from show breeds with long, flowing hair to those in use as model organisms by science. From ca. 1200 AD to the Spanish conquest of the Inca Empire in 1532, selective breeding by indigenous South American peoples resulted in many varieties of domestic guinea pigs, which form the basis for some of the modern domestic breeds. Early Andean breeds were primarily kept as agricultural stock for food, and efforts at improving the Guinea pig as a food source continue to the modern era.