WHAT DOMESTICATION REALLY MEANS
Given the significance of the horse to the advancement of human civilization, it is somewhat ironic that the date and location of the first horse domestication remains so hotly debated. Before considering current knowledge and theories relating to domestication, we must first define it. According to Dr. Jared Diamond, for an animal species to be domesticated they must meet six criteria. They must have a flexible diet (not too cumbersome or expensive), grow up reasonably fast, breed in captivity, have a pleasant disposition, be unlikely to panic, and have a modifiable social hierarchy so that they can recognize a human as its leader.
There is a great difference between a tame animal and a domesticated animal. Giraffes, wolves and bears have been tamed, but are certainly not domesticated. One important measure of domestication is whether an animal born to wild parents would differ in behavior from one born to domesticated parents. For instance a dog is certainly domesticated because even a wolf raised from a pup by humans would be very different from a dog.