Who, what, when, where, and how? These journalistic questions also are the backbone of historic research into the history of the world. There are many scientists who have studied and theorized about how man and horses came to be together, but modern science has changed some of what we thought was fact.

Except for horses and chickens, the farm and pet species we have today are believed to have been domesticated about 10,000-15,000 years ago. It's been fairly well accepted that dogs, cats, goats, sheep, cattle, and pigs all preceded the horse in domestication by a few thousand years. (The chicken was domesticated about the same time or slightly later than the horse.) While it is commonly cited that the horse was first domesticated in Eurasia about 3,000-4,000 BC, scientists still can't say with much accuracy or certainty when, where, and how horse husbandry started.

While some early hypotheses about these questions have held more or less true over the decades, many have been challenged by recent evidence. Inspired by some important new techniques and major findings, research teams around the world have been re-thinking the entire body of evidence related to early domestication of the horse. Their work seems extremely challenging and fun–some of their new hypotheses are fascinating.

What is Domestication?

A species becomes domestic when its care and breeding is managed for generations by humans. Domestication is different from taming, which refers to taking a wild-born animal and keeping it under your care for its lifetime. Tamed wild horses, just like rabbits and other species, were likely kept as pets by many ancient cultures. It was also common practice to capture, tame, and train wild-born horses for work in many ancient cultures.

Researchers expect that the practice of taming wild horses existed long before and even after domestication, and of course was likely the first step in the process of domestication of any species. So when sorting out archaeological evidence for domestication, the question of whether the horses were tame or domestic is not easy to answer.

Domestication of the Horse?

For the horse, there is currently general agreement on the progression of the process of domestication. It is known that wild horses were hunted for meat and bones for making tools as long as 130,000 years ago. Early cultures stayed near horse populations and came to depend upon horse meat for their main source of food. The general style of killing wild horses for meat involved driving groups over cliffs.

After likely a couple of thousand years of this, the first stage of domestication of the horse involved herding and keeping some wild horses, first just as a handy meat supply. The next step would have been to tame the captured wild animals for riding or work. Some scientists suggest that foals orphaned by slaughter of their dams would have been logically available and easily tamed.

The next step would have been to keep the tame horses as breeding animals, whose offspring would be the first generation of domestic stock. There is evidence that in the early phase of domestication, when cultures started to keep and breed horses rather than just tame new ones, that male foals were used for meat before reaching maturity and only mares were raised to maturity and kept as breeding animals and for milk.

For breeding, the mares were tethered near groups of wild horses, where wild stallions would approach and breed them. This practice of breeding domestic mares to wild stallions would have saved early farm families the work, expense, and added challenge of keeping stallions. There is evidence of this practice across several cultures for centuries before stallions born in captivity were kept for breeding.

The Big Questions

One of the broad questions that scholars have debated for decades has been how domestic horses arrived in so many parts of the world. Did the process of domestication happen once in one human culture in one local area? Did the domestic stock from that "single domestication event" travel by trade from place to place around the world, or did the idea of domestication, perhaps along with some of the tools and technology of horse domestication, spread from culture to culture and place to place?

Alternatively, did the whole idea and process of domestication happen independently over and over again in different cultures around the world?

The one local area from which most of the earliest evidence of domestication has been found so far is in the steppes of what is now Kazakhstan. Not very far away in the Ukraine, there is another important site with evidence of early domestic horses. And except for discussion about which of these sites was earlier, until very recently the "single domestication event" theory had been winning out among scholars. In fact many breed historians trace their breed's ancestors all the way back to this one region of the world.

Within just the last few years, evidence from molecular biology has turned the single domestication event theory upside down. Using DNA technology similar to that used routinely these days to confirm parentage of foals, evolutionary geneticists from Sweden have studied the DNA of a large sample of domestic horses and compared it to the DNA found in horse fossils before the time of domestication. What they found is that the genetic material of modern horses is almost as diverse as that of horses before domestication.

If all our modern horses' ancestors were domesticated at about the same time, in the same region, their material would be expected to be much less diverse. In other words, all of them would go back to a few individual ancestors. So this DNA evidence is consistent with the theory that horses were domesticated in many different regions of the world rather than just one area.

Now scholars wonder whether all our focus has been mistakenly on the early sites in the Ukraine and in Kazakhstan, which were attractive because of the excellent preservation of materials buried in permanently frozen ground. It is possible that other early sites of domestic horses existed around the world, but evidence was not preserved in different climates.

While the earliest domestication might not be known yet, one thing is known for sure: It seems like the idea of using horses for transport was a good idea that caught on fast.

During a period of less than 1,000 years during the second and third millennium BC, which is a fairly short time by ancient standards, the use of horses for riding and driving spread far and wide. The evidence is very clear that by that time horses were being used for transport in Asia, Eastern and Western Europe, and China.

Which Came First, the Cart or the Saddle?

Another fun question about the progression of uses of the domestic horse concerns was what work they did first. This, of course, might have varied depending upon the particular culture or region of the world.

Probably the first use of horses for other than for meat, milk, and tools was as pack animals. There is evidence that early nomadic cultures used horses to carry their gear from one place to another. But then which came next, riding or pulling?

One fascinating current research project is aimed at trying to figure out how to know if horses were ridden in ancient times, based on anatomical changes resulting from riding. It is being conducted by a team of scholars in the United Kingdom that is typical of the multidisciplinary approach used these days. It includes archaeologist Marsha Levine, PhD, from the famous MacDonald Institute in Cambridge; veterinary pathologist Katherine Whitwell, FRCVS, Dipl. ECVP, who does post-mortems on domestic horses in Newmarket, England, for her day job; and an equally well-known veterinarian, Leo Jeffcott, BVetMed, PhD, MRCVS, DVSC, MA, VetDr, a clinical equine orthopedic researcher and clinical lameness specialist. Jeffcott was formerly the dean of the veterinary school at Cambridge and has recently relocated to Sydney, Australia, to take over as dean of that veterinary school.

This team has been looking for new ways to use an old approach to determine if ancient skeletons belong to horses that were used for riding. The traditional methods include examining teeth to see if there was wear from a bit, and examining bones of the back to see if there were changes from a saddle. But of course, horses can be ridden without a bit and without a saddle, and it's quite easy to imagine that the earliest ridden horses might have been ridden bareback without a bit.

So far, this British team has found that horses that have been ridden have characteristic changes to thoracic vertebrae. These include deposits of new bone on vertebral bodies and vertebral processes, overriding dorsal spinous processes, and horizontal fissures through the epiphyses. These changes can be measured in the skeletons of ancient horses. So this is a new application of a traditional, simple method that can be useful in determining whether a horse at a particular site had been ridden or not.

Take-Home Message

Domestication of horses is one of those fun topics that doesn't seem to have a whole lot of pertinence in the way we use horses today. However, learning about early man's use of horses, and the types of horses from which our modern stock descends, might hold the keys to certain physical and behavioral traits that we deal with today. Besides, it's fun! From meat animal to domesticated beast of burden to pleasure horse, how did it all happen and what are the ramifications on today's horses? Those mysteries are still being unraveled.


REFERENCES AND READING LIST

Clutton-Brock, J. A Natural History of Domesticated Mammals (2nd ed). London: Cambridge University Press.

Institute for Ancient Equestrian studies. Hartwick College. Oneonta, NY. http://users.hartwick.edu/iaes/index.htm

International Museum of the Horse, at The Kentucky Horse Park. www.imh.org/imh/imhmain.html.

Jensen, T., et al. 2002. "Mitochondrial DNA and the Origins of the Domestic Horse." Proceedings of the National Academy of Sciences of the United States 99.

Levine, M.A. 1999. "Botai and the Origins of Horse Domestication." Journal of Anthropological Archaeology. 18: 29-78.

Levine, M.A. 1999. "Investigating the Origins of Horse Domestication," Equine Veterinary Journal, Supplement 28, The Role of the Horse in Europe, pp. 6-14.

Domestication and Early History of the Horse. In D. Mills and S. McDonnell (Eds), The Domestic Horse: The Evolution, Development, and Management of its Behaviour. London: Cambridge University Press, 2005, p 5-22.

Vilà, C.; Leonard, J.A.; Götherström, A.; Marklund, S.; Sandberg, K.; Lidén, K.; Wayne, R.K.; and Ellegren, H. (2001). "Widespread Origins of Domestic Horse Lineages." Science 291: 474-477.  


FURTHER INVESTIGATION: Who is Studying Animal Domestication?

  • Archaeologists–People who search for and study buildings, graves, tools, and other objects that belonged to people who lived in the past, in order to learn about their culture and society.

  • Archaeozoologists–Archeologists with a focus on the relationship of human cultures and animals.

  • Ethologists–People who study animal behavior.

  • Evolutionary Geneticists–People who study evolution of plants and animals by using the knowledge and technology of the discipline of genetics.

  • Paleopathologists–People who study disease and other pathology of ancient animals and humans.


ARTISTIC DEPICTIONS OF HORSES: Archaeological Evidence of Domestication

Artwork, whether primitive drawings on cave walls or elaborate carvings on objects, is used as evidence of early domestication. It might depict horses in domestic settings, for example within fences, or show their tack.

Writings–Although not common or prolific in the ancient times when horses were likely first domesticated, there are examples of written textual references to horses or tack that have provided useful evidence for domestication.

Tack and Equipments–Archaeologists often find tools and tack that suggest use with horses. In rare instances these are found on the horse skeletons, but often not. One example are findings of antler cheek pieces from bridles.

Human Burial Sites–Ancient burial sites of important people often included objects and animals depicting state-of-the-art technology. An example would be horses buried in full tack. What has been found in some instances is only a bone or antler bit between the teeth of a horse skeleton, which is debated as evidence that horses were domesticated.

Horse Skeletal Changes–Wear patterns are seen on teeth or bones that are consistent with work or tack. A traditional example is wear on premolar teeth from hard bits. Bit wear, when found, is good evidence that the horse was used for work. But if no bit wear is found, the horse might still have been worked using a soft rope or leather bit, or no bit at all. A newer example of skeletal changes due to work are modifications in the shape of the thoracic vertebrae when a horse is ridden.

Horse Biogeographic Distribution–When horse skeletons are found somewhere beyond the geographic areas known to be their natural habitat for that era, it is suspected that the horses were moved by humans, and so were likely domesticated at the time.

Horse Population Characteristics–The horse skeletons found associated with human cultures can be catalogued by sex and age at death. The composition of the "population" of skeletons can provide clues as to whether the horses were from wild hunted herds or managed populations.–Sue McDonnell, PhD, Certified AAB