The horse family (Equidae) appeared in the fossil record in the Eocene, approximately 55 million years ago. Sifrhippus sandrae (also known as Eohippus pernix or Hyracotherium sandrae) was the size of a dog and foraged for food in the warm forests of North America. Its toes spread out to tread on the damp, soft soil and its teeth were suited to eating leaves.
When temperatures began to drop in the Miocene, 20 million years ago, part of the forests gave way to steppes. This new habitat provided opportunities for new species of echidna. Larger species began to appear that relied on a single finger and had the teeth to eat grasses. One example is Dinohippus, which lived 10 million years ago and is seen as a link to modern horses, of the Equus genus.
An analysis of the genomes of fossils and modern equines, carried out in 2013, indicates that the common ancestor of the genus Equus (horse, przewalski, zebra and ass) lived some 4-5 million years ago, in the Pliocene, in North America.
At that time species of Equus migrated via the Beringia Strait to Asia, Europe and Africa and via the Isthmus of Panama to South America. The original horses of the Americas became extinct, probably due to a combination of climate change and hunting by humans. The last fossils are dated to 8-12 thousand years ago.
In Africa, zebras (3 species) and the African donkey (jegue) developed. In Asia, true horses (Equus caballus and Equus przewalski) and two species of ass, the Kiang and the Onager, developed. Horses also arrived in Europe via Asia and the wild horse is generally called the Tarpan. This is the horse we see in cave paintings from 20-30 thousand years ago and is the direct wild ancestor of the modern horse. The Tarpan probably became extinct in the 19th century due to a combination of cross-breeding with domestic horses and the hunting of wild horses.
We know from cave paintings and fossil finds that prehistoric horses were hunted intensively. They probably became extinct in the Americas because of this. Why didn’t this happen in Eurasia?
In fact, the horse almost went extinct there too, but was saved because humans discovered that they could tame and domesticate horses. Where and how this happened is still under discussion. Domestication goes beyond taming wild animals to coexist with humans. It also implies that, through directed selection, humans adapted the species to meet human needs.
One of the first places to have evidence of human-horse coexistence is Krasni Yar in northern Khazakstan. Remains of horses, corrals and the use of horse products dating back 3,500 – 3,000 years A.C. have been found there, linked to the Botai culture. Others point to the Kuban Plains between the Black Sea and the Caspian Sea. In Khvalynsk (Russia), bones of sacrificed horses were found together with domesticated animals and in Maykop (Russia), in addition to bones, paintings of horses were found inside a kurgan (typical tomb of the region).
Initially, horses were probably ridden to control herds. But the homo-caballus partnership, supported by other technologies, made the “equestrian culture” develop and spread rapidly across the steppes of Eurasia and other regions.
The domestication of horses coincides with the appearance of the wheel. The invention of a wheel with rims and spokes around 2200 BC gave rise to the possibility of the war chariot, where one person drove the horses and another could shoot with a bow and arrow. One of the earliest images of this is from the Sumerians (southern Mesopotamia). Tombs with horses and chariots have been found in the Sintashta culture (on the border between Russia and Khazakstan).
The use of bows and arrows is older (10,000 BC), but it was the invention of the compound bow (2000 BC) that made it possible to make smaller, more powerful bows, allowing them to be used on a mounted horse. With the evolution of the saddle, stirrup and muzzle, as well as riding, the steppe nomads became powerful invading forces in Europe, Asia and North Africa.
The Scytios were one of the first peoples to dominate the steppes on the basis of mounted archery. They emerged around 900 BC in southern Siberia and came to control an area from the Carpathian Mountains to western China. Their battles with the Greeks, Assyrians and Persians are famous.
Their great tombs, or Kurgans, are still scattered across the steppes. Those that have been excavated show their rich culture and art and their intimate connection with horses, which were buried. The permafrost helped preserve the bodies of men, their clothing, their weapons, their jewelry, the horses and equestrian material. The equestrian material indicates that the Scythians must have been expert horsemen, who didn’t need crude mouthpieces to ride their horses.
Analysis of the DNA taken from the remains of the Sintashta and Scitios horses reveals that these peoples already bred horses and selected for color, speed, gait and stamina, and probably docility. At that time there was still a good genetic variety of male horses.
A recent study of modern horses shows that human selection in the paternal line has eliminated this variety. Today, almost all stallions have the Y chromosome descended from just two lines of horses of oriental origin (Turkoman or Arabian). Only breeds such as the Fjord, Icelandic and Shetland have different ancestry.
There’s a lot more about equestrian history and culture in Bjarke Rink’s books and the Unraveling the Centaur Enigma Course.