More than 50 million years ago, a small fox-sized animal crept through the forests of North America, feeding on fruit and leaves. Its arched-back body was only about a foot high at the shoulder. It had a long tail and a short-snouted head, which gave it a distinct dog-like look. In fact, its feet had pads that would resemble a dog's, except each toe ended in a tiny hoof instead of a claw. Interestingly, in modern horses, one toe has become the hoof, and the others remain as vestigial bumps higher up the leg. Now they gallop and trot, whinny and neigh, capturing our imagination, and our hearts. Indeed, horses are said to have done more to change human history than any other domestic animal, once upon a time carrying explorers to new frontiers and mighty armies to great conquests.