You approach with caution, drawn to their equine beauty. The sleek stallion, the magnificent mare, and the gentle foal look like any happy family. But don't get too close. These are wild horses, untamed by humans. Now photographers Yva Momatiuk and John Eastcott take you inside the world of the wild horse. This husband-and-wife team of committed experts makes a case for the conservation of one of America's favorite wild species.