Have equi-asinine sexual relations been going on forever, or were mules “invented” long ago by some enterprising human with a penchant for very odd experiments?
This doesnt say anything about when it started, but its better than nothing:
Mules
I’d vote for going on forever, or at least as long as horses and donkeys have been domesticated and kept together. No very odd experiments are necessary. Horses and donkeys aren’t in the least bit shy or reluctant to interbreed in captivity ( there are behavioral and ecological barriers in the wild, though doubtless it has happened occasionally ). Keep them in the same pen/field and you’re going to get little baby mules.
- Tamerlane
And mules get pregnant sometimes. It’s rare, like maybe 3 or 4 times on record, but it happens. It just happened again, I believe I read a blurb about it in the latest Discover.