I find it fascinating that things part of common knowledge today were discovered relatively recently. Here is something not known in the 1860s, from Darwin’s Origin of the Species, p 29-30:
I do not believe, as we shall presently see, that all our dogs have descended from any one wild species; but, in the case of some other domestic races, there is presumptive, or even strong, evidence in favour of this view.
The whole subject must, I think, remain vague; nevertheless, I may, without here entering on any details, state that, from geographical and other considerations, I think it highly probable that our domestic dogs have descended from several wild species.
We now know that all dog breeds are descended from wolves through a domestication event or several closely spaced domestication events about 100,000 years ago. This explains why dogs are found with aboriginal human groups throughout the world.
This is from a section describing how in most domesticated animals have many breeds or varieties yet are descended from a single wild species. In the 1860s, the the evidence pointed to more than one wild ancestor for dogs.