There are many breeds of guinea pig or cavy which have been developed since its domestication circa 5000 BCE. Breeds vary widely in appearance and purpose, ranging from show breeds with long, flowing hair to laboratory breeds being used as model organisms for science. From roughly 1200 to 1532 CE (during the Spanish conquest of the Inca Empire), selective breeding by indigenous South American people resulted in many landrace varieties of domestic guinea pigs, which form the basis for some formal modern breeds. Early Andean varieties were primarily kept as agricultural stock for food, and efforts at improving cavy breeds (cuy) bred for food continue to the modern era, with entirely separate breeds that focus on size and disease resistance.