Diet

A remarkable fossil specimen of the equoid Propalaeotherium, from the late Eocene epoch was found complete with fossilized stomach contents, which included grape pits. Climatic changes of the Miocene epic, gave rise and increase to size and shape of the equoid species. That started when the ancestral horse began to eat grasses. Modern times has brought many varieties of horse feeds. Modern equine dentistry has brought longevity to these functionary feeds. Basically, what I'm saying is, that millions of years of adaptation, from forest browser to grass eating prey animal allowed their brain size to increase. So, that while feeding low to the ground, they kept an eye out for the hungry carnivorous predator. The extra cup of morning coffee, that we as humans have adapted to, makes you five minutes late to feed your modern fed, time scheduled, six hundred pound mule, she can now pick the lock on the gate, freeing her and her cronies to unlimited hay access.