Whos the Boss?
Horses have a strong instinct to form groups in which some horses lead and others follow. A typical family group consists of one male, several females, and their offspring. The male stallion fights off predators and rival stallions, but the leader of day-to-day activities is usually a female. This lead mare decides where the group should go and punishes misbehavior. Every horse knows whether it is dominant or submissive to every other horse. If a new horse joins the group, it quickly sorts out where it stands.
Follow the Leader
Horses live in well-structured groups with clear followers and leaders. Without any human training, horses will line up behind a lead mare according to their rank in the herd, usually with a stallion guarding the rear.
By controlling the movement of horses with ropes and fences, humans can establish their dominance. Eventually, the horse will submit to being led around by a thin rope, or no rope at all, even though the horse is the stronger animal. One reason this works is that horses instinctively submit to a more dominant individual that controls their movements.
Dominance relationships are very important among horses. In fact, a faster horse will sometimes lose a race to a slower horse that expresses dominance through its body language. For people, the key to working with horses is to make it clear who is in charge. If you act unsure, the horse may ignore your commands.