The origin of the equine species can be traced back 60 million years ago to the Eocene period. In 1867, scientists excavating rock structures of that period in the American South discovered a complete skeleton of what became known as the first horse. They called it Eohippus meaning The Dawn Horse.

Eohippus descends from the Condylarth, a group that was the distant ancestor of all hoofed creatures and lived on Earth about 75 million years ago. The Condylarth was no bigger than a dog and was five-toed, with each toe having a horny nail.

Fifteen million years later, the feet of Eohippus altered. On the forefeet were four toes and on the hind there were three. This creature was thought to have weighed about 12lb on average and stood about 14in at the shoulder. This is about as big as a medium size dog. The texture and color of the Eohippus' coat is not known, but it was thought to be like that of a deer, the background being dark with lighter spots or blotches. This would provide the animal with camouflage in his forest surroundings.

The toed feet were equipped with pads like that of a dog. This revealed that the Eohippus lived in an environment that included the sort of soft soil found on jungle floors and around the edges of pools. The pads enabled the animal to cross wet and marshy ground without difficulty. Neither the eyes nor the teeth bore much resemblance to those of the modern horse. The teeth were more like those of pigs or monkeys, but they were well suited to a diet of soft leaves growing on low shrubs.

Eohippus was succeeded by two similar and probably overlapping types in the Oligocen period, 25 - 40 million years ago. These were Mesohippus and the slightly more advanced Miohippus. Both of these animals were bigger with longer legs and were equipped with teeth that enabled them to eat a variety of soft plants. Their toes were reduced to three on each foot, with most of the weight supported by the center toe.

The watershed in the development of the horse occurred between 10 and 25 million years ago in the Miocene period. During this period, the jungle environment gave way to treeless plains and steppes, supporting a low growth of wiry grasses. Adapting to these changed conditions, the horse developed teeth that were suitable for grazing and a longer neck to make the grasses easier to reach. The position of their eyes altered to give them all around vision against the approach of predators. Their legs became longer and were equipped with flexing ligaments and, eventually, a single toe or hoof. All of these changes increased the speed with which it could flee if an attack was imminent.

Pliohippus was the first single hoofed horse which evolved 6 million years ago. Pliohippus was the prototype for the true horse, Equus caballus, which was established a million years ago. This was half a million years before man.

Equus spread from America over the existing land bridges to Europe and Asia. When the glaciers retreated, maybe 10,000 years ago, the land bridges had disappeared and, for reasons which could only be speculation, the horse became extinct on the American continent. It was not re-established until the arrival of the Spanish conquistadores.

The three principal, primitive types of horses evolved according to the dictates of environment and may therefore be considered as the foundation for the world's breeds. They were the Asiatic Wild Horse, which still exists in zoos; the lighter, more refined Tarpan of Eastern Europe and the Ukranian Steppes, which is exemplified by the famous herd maintained at Popielno in Poland; and the heavy, slow-moving horse of the northern European marshlands known as Equus silvaticus, from which our heavy horse breeds derive.

Just prior to domestication, four sub-species had evolved - two pony types and two horse types. Pony Type 1 was similar to today's Exmoor pony and became established in Northwest Europe. It was resistant to wet and thrived in harsh conditions. Pony Type 2 was bigger and more heavily built. It inhabitated northern Eurasia and was able to withstand the cold. The Highland pony most nearly resembles this type. Horse Type 3 was about 14.3hh. Long and narrow bodied, goose-rumped with long neck and ears. This type inhabitated central Asia. The nearest modern equivalent to this type is the Akhal-Teke, a breed that is able to tolerate heat. Horse Type 4, while smaller than the others, was much more refined, with a concave profile and high-set tail. It came from western Asia and its present equivalent is the Caspian pony. It is postulated as the prototype Arabian.

Reference: The Ultimate Horse Book; Elwyn Hartley Edwards; 1991