1st bioengineered hybrid animals discovered — in ancient Mesopotamia

Have you ever been around livestock or wild animals, when they come in heat? Especially the larger animals. The problem is keeping them separated, not bringing them together.

Just release the donkey in the asses' neighborhood, and collect a little later. The hybrids, were probably a worthless product, until a use could be found. Breeders probably fought and penned off wild Syrian asses from the domestics.

Just a guess from experience.