Horse behavior is best understood from the view that horses are prey animals with a well-developed fight-or-flight response. Their first reaction to a threat is often to flee, although sometimes they stand their ground and defend themselves or their offspring in cases where flight is untenable, such as when a foal would be threatened.Nonetheless, because their physiology is also suited to a number of work- and entertainment-related tasks, humans domesticated horses thousands of years ago, and they have served humans ever since. Through selective breeding, some breeds of horses have been bred to be quite docile, particularly certain large draft horses. On the other hand, most light horse riding breeds were developed for speed, agility, alertness and endurance; building on natural qualities that extended from their wild ancestors.The instincts of horses can be used to human advantage to create a bond between human and horse. These techniques vary, but are part of the art of horse training.