Elephant was domesticated by 5000 B.C. through Mesopotamian, Turkestan, and Chinese farmers.  Blue man was successful in taming the elephant.  It was easy to tame some animals, but like the elephant, many of them would not reproduce in captivity.  Straight-tusked elephants entered Europe from Africa, over the Sicilian land bridge.  Mice reproduce much more rapidly than elephants, yet elephants evolve more rapidly than mice.  800,000 years ago, Neanderthals hunted elephants. 
The huge elephants of older and subsequent periods possessed large brains as well as large bodies, and they soon overran the entire world except Australia. Elephants have greater emotional control than horses, albeit at the disadvantage of agility. However, of all the animals it is the most intelligent, and its intelligence is only surpassed by man.  Though long departed, the massiveness of the passing Reptilia found echo in the elephant and mastodon.  Miocene was age of horses and elephants.