Horses are prey animals with flight or fight instinct. Their first response to threat is to flee, although they are known to stand their ground and defend in cases where less capable horses would be left exposed, such as when a foal would be threatened. Horse people commonly say that inside every domestic horse is a wild horse. Through selective breeding, some horses have been made more docile, but most sport horse breeds are based on the principle of preserving the natural qualities that existed in horses that were taken from wild herds hundreds of years ago.

Horses are highly social and intelligent herd animals. Like many other herd animals, their society is derived, or has evolved from survival instincts. At the center of the herd is the alpha or dominant mare. The center of the herd is the safest because it is further away from predators than any other part. The edge of the herd is where the lowest on the social order are found. Punishment is delivered in the form of expulsion from the herd on a temporary or even permanent basis.

Herds are made up of mares, foals and immature horses of both sexes. Survival of the species dictates that females and foals are of primary importance, because they give and nurture life. Only a few males are needed--on a very temporary basis--to continue the species. The herd of twenty mares could produce twenty foals in one year. They only need one or more stallions to impregnate all of them.

When colts become mature stallions they leave to roam in small bachelor herds. They are no longer welcome in the herd. Some of these horses may battle for the privilege of the most dangerous position in the equine world: dominant stallion.

The dominant stallion lives in the most dangerous and tenuous position in the equine world. He lives on the periphery of the herd, exposed to predators and other bachelors who will fight him for that role. In stark contrast to the mythology of the stallion and his (ownership implied) harem, he has no value to the herd. He is totally dispensable since he is easily replaced. The male dominance hierarchy ensures an immediate replacement by a strong and healthy successor at any time.

The ability of humans to work in cooperation with the horse is based on the strong social bonds that horses have with each other. Horses do not like to be separated from the herd, because to be alone is to be exposed to predators on all sides. Horse training principles are based upon having the horse accept a person as the dominant herd member, not through force, but by virtue of ability and confidence. It is those attributes that are highly valued because they point the way to survival. A horse that is afraid more than necessary will expend energy needlessly and may not be able to escape when the threat is real. In pastures, it is the rule that horses tend to gravitate around the most mature and confident members.

As with many animals that live in large groups, establishment of a stable hierarchy or pecking order is important to smooth group functioning. Contention for dominance can be risky since one well placed kick to a leg could cripple another horse to such an extent that it would be defenseless, exposed, and possibly unable to get to water. Survival dictates that the herd members ultimately cooperate and stick together. The alpha or dominant mare exercises control over herd members to moderate aggressive behavior.