What TWO species of animals have domesticated animals?
Humans and Ants
Humans and Primates
Humans and Spiders
Humans and Dogs
I cannot fully agree on this one, for several reasons. The first reason is that humans are primates, so in the answer "humans and primates" "humans" seems superfluous. The second is that I've seen a documentary or something in which baboons were shown that kept guard dogs (I think that was somewhere in South America).
Besides, I've looked it up with google and found this:
http://primatology.net/2010/07/05/do-animals-keep-pets/
This article states:
The author believes that humans are “true” pet owners because the owner-pet relationship occurs in a natural setting and argues that animal pet owners are not “true” pet owners because they do so in captive or semi-captive settings. Thus, Herzog believes that humans are the only animals that keep pets.
However, I do think I remember hearing something about ants that keep domesticated animals. (Unfortunately I cannot remember what kind of animal they kept.) But when I tried to look up "ant with pet", I couldn't find anything relevant.
Oh, now I've found it! Here it says:
Some ants keep "cows," and even build tiny barns of leaves for them. The cows are aphids, or plant lice. The ants milk the cows by stroking them on their backs with their antennae, giving them a sweet, clear milk called honeydew.
http://www.homeschoolgazette.org/FlabFacts.html
That is what I've heard. They keep aphids and collect the (honey)dew from their backs.
I'm convinced about the ants again, but I think primates should be correct as well, because they somtimes seem to keep pets, too. (Even though that primatology.net says that monkeys are not "true pet owners".)