The modern domesticated horse (Equus caballus) is today spread throughout the world and among the most diverse creatures on the planet. In North America, the horse was part of the megafaunal extinctions at the end of the Pleistocene, but not, for some reason, in Europe. Two wild subspecies survived until recently, the Tarpan (Equus ferus ferus, died out ca 1919) and Przewalski's Horse (Equus ferus przewalskii, of which there are a few left).
Horse history, especially the timing of the domestication of the horse, is still being debated, partly because the evidence for domestication itself is debatable. But interestingly, genetics seems to suggest a single event of domestication. Unlike other animals, criteria such as changes in body morphology (horses are extremely diverse) or the location of a particular horse outside of its "normal range" (horses are very widespread) are not useful in helping resolve the question.
Horse History and the Evidence for Horse Domestication
The earliest possible hints for domestication would be the presence of what appear to be a set of postmolds with lots of animal dung within the area defined by the posts, representing a horse pen. That evidence has been found at Krasni Yar in Kazakhstan, beginning about 5000 BC. The horses may have been kept for food and milk, rather than riding or load-bearing.
Accepted archaeological evidence of horseback riding includes bit wear on horse teeth-that has been found in the steppes east of the Ural mountains at Botai and Kozhai 1 in modern Kazakhstan, around 3500-3000 BC. The bit wear was only found on a few of the teeth in the archaeological assemblages, which might suggest that a few horses were ridden to hunt and collect wild horses for food and milk consumption. Finally, the earliest direct evidence of the use of horses as beasts of burden-in the form of drawings of horse-drawn chariots-is at about 2000 BC, in Mesopotamia.
Horse History and Genetics
Genetic data, interestingly enough, has traced all extant domesticated horses to one founder stallion, or to closely related male horses with the same Y haplotype. At the same time, there is a high matrilineal diversity in both extant and wild horses. At least 77 wild mares would be required to explain the diversity of the mtDNA in current horse populations, which probably means quite a few more.
New Evidence
In a paper published in Science on March 6, 2009, Alan K. Outram and colleagues looked at three strands of evidence supporting horse domestication at Botai culture sites: shin bones, milk consumption, and bitwear. These data support domestication of the horse between about 3000-3500 BC sites in what is today Kazakhstan.
Horses skeletons at Botai Culture sites have gracile metacarpals. The horses' metacarpals-the shins or cannon bones-are used as key indicators of domesticity. For whatever reason (and I won't speculate here), shins on domestic horses are thinner-more gracile-than those of wild horses. Outram et al. describe the shinbones from Botai as being closer in size and shape to those of Bronze age (fully domesticated) horses compared to wild horses.
Fatty lipids of horse milk were found inside of pots. Although today it seems a bit weird to westerners, horses were kept for both their meat and milk in the past-and still are in the Kazakh region as you can see from the photograph above. Evidence of horse milk was found at Botai in the form of fatty lipid residues on the insides of ceramic vessels.
Bit wear is in evidence on horse teeth. Finally, researchers noted bitting wear on horses' teeth-a vertical strip of wear on the outside of horses' premolars, where the metal bit damages the enamel when it sits between the cheek and tooth.
White Horses and History
White horses have had a special place in ancient history-according to Herodotus, they were held as sacred animals in the Achaemenid court of Xerxes the Great (ruled 485-465 BC).
White horses are associated with the Pegasus myth, the unicorn in the Babylonian Arabian horse, Lipizzaner stallion, Shetland pony, and Icelandic pony populations.
Sources
For information on white horses, see White Horses and Genetics and More about White Horses.
This article is part of the Guide to the History of Animal Domestication.
Brown, D. and D. Anthony 1998 Bit Wear, Horseback Riding and the Botai Site in Kazakhstan. Journal of Archaeological Science 25(4):331-347.
Cassidy, R. 2009 The horse, the Kyrgyz horse and the 'Kyrgyz horse'. Anthropology Today 25(1):12-15.
Jansen, T., et al. 2002 Mitochondrial DNA and the origins of the domestic horse. Proceedings of the National Academy of Sciences 99 (16):10905-10910.
Levine, M. A. 1999 Botai and the origins of horse domestication. Journal of Anthropological Archaeology 18(1):29-78.
Ludwig, A., et al. 2009 Coat Color Variation at the Beginning of Horse Domestication. Science 324:485.
Kavar, T. and P. Dovc 2008 Domestication of the horse: Genetic relationships between domestic and wild horses. Livestock Science 116(1-3):1-14.
Outram, A. K., et al. 2009 The Earliest Horse Harnessing and Milking. Science 323:1332-1335.
Rosengren Pielberg, G., et al. 2008 A cis-acting regulatory mutation causes premature hair graying and susceptibility to melanoma in the horse. Nature Genetics 40:1004-1009.
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