Adaptations of Domestic Horses

Horses known scientifically as "Equus caballus" have been domesticated for thousands of years, with the practice beginning as far back as 4,000 B.C. Feral populations of horses such as mustangs exist in the wild but they descend from animals that were domesticated at one time.Today, a wide range of horse breeds exist and although they all share common traits, they also have a number of differences.

  1. Unnatural Adaptations

    • Domestic horses are found in a variety of sizes and due to selective breeding, they have developed unnatural adaptations. A breed such as the Shire Horse, for instance, was bred to be large; selective breeding has caused its joints and muscles to adapt to take on the strains of this increased size. Shetland Ponies that developed on exposed islands north of Scotland adapted to have thick, shaggy coats that protected them against the elements. Certain kinds of horses have also been bred to adapt and perform specific tasks. Large and heavily-muscled horses do pack work while slender horses, such as Arabians, are excellent for speed and endurance.

    Natural Adaptations

    • No matter what the breed, all horses share common adaptations. As a defense against the irritation caused by insects biting around their hindquarters, all horses swish their tails -- which they come by naturally -- to deter and swat at insects. When horses walk on rough, rocky ground or on roadways, their hooves wear down. Consequently, hooves grow at a rapid rate of about 1/4 inch per month. Horses' large bodies and the overall physical strain they endure naturally requires that they have a powerful heart. An average sized horse has a heart that weighs approximately 9 lbs.; the size of the heart differs in smaller and larger breeds.

    Behavioral Adaptations

    • Due to their large bodies and relatively slender legs, standing up from a laying down position can be taxing for a horse. They have adapted by sleeping mainly while standing up and only rarely lay down. Horses prefer to live naturally in herds that generally have a social dominance structure. In the wild and in some domestic herds, a dominant male will have a harem of several females it will breed with and protect. This behavior ensures that the strongest and fittest males pass on their genes. Within the herd, social bonds are also forged and maintained when the horses groom one another.

    Predator Defense

    • Like many large herbivores, horses have adapted for predator defense. Their eyes are located on the sides of their heads, which enables them to watch for predators and see nearly 360 degrees around. A keen sense of smell also helps the horse be alert for possible danger as the horse will pick up unusual scents in the air easily and be warned of an approaching predator or threat. Once again, the horse's ability to sleep while standing comes in handy as the animal is less vulnerable if it does not appear to be at rest. Living in herds is also beneficial for safety as strength in numbers serves as protection in and of itself; more eyes increase the number of lookouts for potential danger.