the horse, Equus ferus caballus, is a subspecies of the Equidae family. Over the past 50 million years, through adaptations for survival, the common horse has evolved from a relatively small, multi-toed animal into the large, single-toed animal known today (Wilson, Mammal Species of the World (3rd ed. .). Domestication of the common horse is believed to have begun around 4000 BC, becoming common by early 3000 BC (Wilson,. Mammal Species of the World (3rd ed.). Baltimore). Domestication is a process in which wild species are removed from their natural habitat and are acclimated to survive and breed in captivity. Animals are domesticated for purposes that, in general, are designed to be beneficial to humans. These reasons commonly include work, food sources, and companionship. Over generations, domestication causes genetic and physiological changes in the organism (Wilson,. Mammal Species of the World (3rd ed.). Baltimore). Domestication is different from domestication in that domesticated animals are born in the wild, are removed, trained, and the process repeats, while domesticated animals are bred in captivity (Merriam-Webster Dictionary, 2nd edition). Although most horses today are domesticated, in some countries there are critically endangered wild horse populations, including the Przewalski's Horse, found in Central Asia (Foundation for the Preservation and Protection of the Przewalski's Horse, 2008) . Depending on mitigating factors such as environment and breed, the domestic horse has a lifespan of 25-30 years. Horses undergo various stages of development, and a horse can be further defined (Ensminger Horses and Horsemanship pp. 46–50). A young horse of either sex, less than a year old, is known as a colt...... middle of paper... cheerfully, Sam is much bigger and stronger than me, and chooses to let me be his friend of his own free will. If he doesn't want this attention, he has the means to let me know. Sam is happy when he sees me and when he hears my voice. He can pick out my voice and face from a crowd. When I walk to his paddock and call his name, he usually approaches the gate, delighted to have my attention. In return for what I do for Sam, he loves me back. Sam does his best to keep me on my back when I'm falling and always works at his best level when being ridden. Try to give me everything I ask for, as I do the same for him. In general, he and many other domestic horses are happy and healthy, most likely much happier and healthier than wild horses. I believe that domestication is beneficial not only to humans, but more importantly, to horses as well.