familiaris, and on the next page he classified the wolf as Canis lupus. Linnaeus considered the dog to be a separate species from the wolf because of its head, body, and cauda recurvata - its upturning tail - which is not found in any other canid.

In 1999, a study of mitochondrial DNA indicated that the domestic dog may have originated from multiple wolf populations, with the dingo and New Guinea singing dog