Researchers who looked back on 5500 years of horse domestication have a warning for today’s breeders: The fast-paced push for desirable traits can result in a drastic reduction in genetic diversity within only a few generations.
Weronika Klecel and Elżbieta Martyniuk, writing in the journal Animals, said five millennia of horse domestication has been characterized by slow but steady improvements in breeding.
“The intensive selection implemented in the last 200 years, combined with novel reproduction techniques not older than 50 years, raises questions about the future of horse breeding,” they said.
“Breeders are able to achieve the desired phenotypes within a few generations, but this comes with the cost of drastic reduction in genetic diversity.
“The massive extinction of ancestral breeds in the 20th century is a warning to modern breeders that the dynamic pace of phenotypic improvement can result in irreversible loss in the genetic makeup of the species.”
The pair, with the Institute of Animal Sciences at the Warsaw University of Life Sciences in Poland, noted that horses were domesticated later than any other major livestock species, about 5500 years ago on the Eurasian steppes as a source of meat and secondary products, such as milk.
With the invention of light, spoked-wheel chariots around 4000 years ago, chariot-driven horses became a primary means of transportation and an asset in warfare.
The importance of horses and chariots and the substantial cost and expertise needed for their management led to the development of specialized horse-related professions.
“Their role in shaping ancient civilizations cannot be overestimated,” the pair said. “Vast amounts of money were invested in the horse industry resulting in the rapid development of horse breeding and husbandry.”
In their review, the pair examined the evidence on managing horses in antiquity, finding that many ancient approaches and practices in horse management are still relevant today. Some, now abandoned, are worth re-examination, they said.
Klecel and Martyniuk said the first nomadic horse-keepers most likely managed their herds in a non-invasive way, by maintaining them in family groups and letting them breed within these groups.
Their usefulness in transport and warfare meant horses became especially valuable, the pair likening them to luxury goods.
“The quality of a horse was measured mainly by its usefulness in battle, and later, especially in the Roman Empire, its racing performance,” the pair said.
“Various traits associated with warfare and racing were proven to be a subject of selection in the ancient era, including height at the withers, limb development, behavior, and high-speed potential.
“It is challenging, however, to determine the specific methods of selection used by ancient breeders,” they said.
From the works of ancient authors, it can be concluded that the breeding value evaluation was based primarily on the conformation of animals and general impression, rather than their utility or pedigree.
In the Roman Empire, it seems that horse herds used for breeding and those kept for other purposes, including riding or performances in circuses, were kept separately. Roman circuses were venues for chariot races, horse races, gladiatorial combat, and performances that commemorated the empire.
Apart from transportation and use in battles, horses were also widely used for racing, which derived directly from war maneuvers.
“The scale of horse racing in the Iron Age was comparable to today’s racing in Great Britain and France, with its role in society even more significant than today,” Klecel and Martyniuk said.
“It is worth noting that the Greeks and Romans were aware of the importance of factors such as rider/driver weight carried by the horse, as well as their skills, the significance of which is still being researched today.”
The pair said the relevance of Greek and Roman horse husbandry practices remains high, even in the modern era.
“The general rules of stable management have not changed much, while feeding and training systems have undergone modernization but still are based on the historic principles.”
The training system described in the so-called Kikkuli Text from 4000 years ago demonstrates that following the old rules can be beneficial, they said, especially for trainers who seek to improve the endurance of horses.
These tablets from northern Syria describe organized teams of charioteers, trainers, and stable staff. They describe in detail training methods for chariot horses. The training program lasted 214 days and, in addition to feeding instructions, contained a schedule of interval training, swimming, massages, blanketing, clipping, turning out to paddocks, and other elements – all well-known to modern horse trainers.
At the beginning of the 1990s, six Arabian horses underwent the Kikkuli training program, and, as stated by the researcher, the resulting endurance improvement was incomparable to any modern programs.
Klecel and Martyniuk noted that Roman horsemen desensitized their horses from an early age to handling and harnesses. At three years of age, the youngsters were broken under the saddle, and light exercise was introduced.
At five years of age, circus horses underwent an evaluation, after which they were placed in one of two chariot positions and began their racing careers, sometimes lasting up to 15 years.
The exact time and place of the beginning of horse medical treatment remain unknown. The first documented case of the “horse doctor” is Metrodoros from Lamia in Thessaly about 2200 years ago, but it is safe to assume that the profession existed long before him.
There is no exaggeration in saying that the foundation of modern horse veterinary care – hippiatrics – reaches back to the ancient era, and that no other species received as much medical attention as the horse.
In the Roman Empire, the status of veterinary practitioners varied immensely. They could be divided into three main groups: Slaves, working mainly for the post office and sometimes the circus; free practitioners who had some restrictions regarding their charging for services rendered; and veterinary surgeons, hired usually by the army, and considered prestigious members of the society.
Horses were not cheap, either.
The spread of horses from the Eurasian steppes into other parts of Europe resulted in their exchange and trade. Over time, horses became a luxury item, and in the Iron Age, they were reserved for the richest part of society.
“The average cost of a cavalry horse in Greece, a country not particularly geographically suited for raising horses, reached about five hundred drachmae. For that price, one could purchase ten cows or three slaves. That amount was also equal to one and a half year’s pay of the average Iron Age Athenian.”
In the Roman Empire, the average horse price of 125 denarii was equal to a secretary’s pay for seven months, or a private soldier’s pay for six months.
“We also know that, despite good road infrastructure, most civilian Romans travelled on foot.
“Given that the only purpose of horse breeding and racing was to provide prestige for the owner through competition-winning, that activity must have been reserved for the highest classes of the society.
“Due to high value, horse possession required special expertise, which led to the development of many new professions to cover various aspects of horse utilization.”
Klecel and Martyniuk said that horse breeding and management are truly the results of the continuous evolution of practices.
“The importance of the horse is clear from the investment made in their development and enhancement of the scope of their uses.”
Understanding their history is important in guiding the future development of horse management, they said, which gave rise to their warning over the continued potential loss of genetic diversity through modern breeding practices.
Slow but steady breeding improvements from the ancients have given way to the intensive selection implemented in the last 200 years, as well as the use of novel reproduction techniques introduced in the last 50 years.
Breeders can bring about change within a few generations, but at a cost of genetic diversity.
The losses seen in ancestral breeds in the 20th century should serve as a warning, they said, that the dynamic pace in attempting to improve horse can result in an irreversible loss in the genetic makeup of the species.
Klecel, W.; Martyniuk, E. From the Eurasian Steppes to the Roman Circuses: A Review of Early Development of Horse Breeding and Management. Animals 2021, 11, 1859. https://doi.org/10.3390/ani11071859