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Recent advances in understanding domestication and the impact on our horses today.

Recent advances in understanding domestication and the impact on our horses today.

Written by Sharon Smith MSc SEBC(Reg) IEng BHSAPC

There has been some exciting new research published in 2018, challenging our
perceptions regarding horse domestication and ancestry. But does this change anything for the modern equestrian?

Most equestrians know horses co-evolved with grass over millions of years on wide-open plains, reliant on safety in numbers, social skills, and keen senses to escape predation. Food intake rate is maximised with the ability to breathe without a lip-seal (‘obligate nasal breathing’), the lips instead searching constantly for the next bite while chewing the last, and then front teeth capable of tearing grass down to the level of bare earth. Their digestive system allows them to sprint short distances immediately after eating, with no need to waste hours regurgitating and chewing cud (like cattle and sheep).

Horses can survive winters on a sparse supply of diverse, low quality plant species, where farm animals would die [1,2,3]. So farmed horses were the sole source of food for the Botai culture in north Kazakhstan by at least 3700BC. Horse milk is a rich source of vitamins and minerals – and surplus male horses were raised for meat[3]. They were selectively breeding for a spotted coat, a genetically disadvantageous trait associated with poor night vision[4]. The conditions on the Western Steppe would not allow the Botai to grow crops, even if they had the tools to harvest, so the horses had to be outside and allowed to roam in order to graze on poor quality grass. Rawhide hobbles prevented escape. By the Bronze Age, pastoral practices were established across the Steppe, a half-way- house between sedentary farming and nomadic lifestyle – naturally rotating pastures systematically. Horses were being ridden [1] by the Kazakhstan-based Yamnaya and other Steppe cultures who last migrated[5] with their horses across Europe to trade around 2000BC.

Around 1000BC, horses had integrated into human lives and cavalry was invented [2]. Romans were reliant on their horses every day, so could not risk their capture. Horses were still only pony-sized so were stabled in groups of 3, in 3.6m x 3.6m ‘rooms’ with a roof and a door opening to the outside air. Their riders slept in an adjacent room at the back of the stable. Gutter installations enabled the stable floor to remain dry, reduce pungent odour from urine, and avoid thrush in the foot [6,7]. Horses were fed hay, with some grain if necessary as a substitute for pasture.


Y-chromosome DNA evidence suggests this new ‘living arrangement’ between man and horse might have caused behaviour problems and only the most compliant stallions were tolerated and bred from [8,9,10]. By the time of Jesus Christ, almost all equine male diversity was lost. The Steppe stallion bloodlines were perhaps out-bred by stallions founded in Europe [8]. Even the present-day Przewalski horses in Mongolia are now thought to be a feral descendant of escaped Botai domestic horses [4]. At least in the male lineage, there is no living trace of a wild horse left on this planet today.

Yet, regard the evolutionary drivers that created all horses: social living; a diet made almost entirely of diverse grass species; movement; clean air and shelter [11]. Our domestic horses struggle to cope when these needs are not met. Stereotypy and depression-like behaviour has been associated with abrupt early weaning, high-grain diets, prolonged confinement and social isolation[12]. Stress (caused by isolation, chronic illness, fear and lack of stimulation) is associated with gastric ulcers and poor performance[13]. Performance horses are often given starch-laden feeds in order to compensate for limited appetites. A dutch-barn of indoor stables and indoor arena may seem perfect to us, but the horse’s respiratory system is easily compromised. Equine asthma and Inflammatory airway disease is a modern disease of polluted air.

Even the Roman army came closer to meeting evolutionary needs than some modern-day yards. Their facilities were not so different to ours, but their management was. Their horses moved and worked outside for most of the day with people and other horses and were fed hay. They knew the importance of a clean floor and clean air – living in the same space as their horse. If our horses can’t be out in the fresh air all day, they should be kept as free from dust and ammonia, as possible. Oil is twice as calorie-dense as starch, sugar or protein. Fed alongside quality hay and added vitamins/minerals, it is a diet that meets all nutritional and energy needs but can save many hundreds of pounds, per horse per year [14]! Conditioning the horse’s metabolic processes to oil in the diet can even improve stamina at maximum effort [15] and forage-based diet is widely accepted to reduce the risk of gastric ulcers.

Regardless of handling and training method, history tells us to base our management on understanding the environmental and human drivers that founded the breed, then work to reconcile the differences with our reality. With new genetic evidence suggesting there wasn’t just one founder stallion on the Steppe, the old adage that we should ‘treat each horse as an individual’, has perhaps never been more relevant.

References:
[1] TAYLOR, W. T. T. (2017). The origins of horse herding and transport in the Eastern Steppe. PhD Dissertation
[2] Anthony, D. W., & Brown, D. R. (2011). The secondary products revolution, horse-riding, and mounted warfare. Journal of World Prehistory, 24(2-3), 131.
[3] Olsen, S. L. (2006). Early horse domestication on the Eurasian steppe. Documenting domestication: new genetic and archaeological paradigms, 245-269.
[4] Gaunitz, C., Fages, A., Hanghøj, K., Albrechtsen, A., Khan, N., Schubert, M., ... & de Barros Damgaard, P. (2018). Ancient genomes revisit the ancestry of domestic and Przewalski’s horses. Science, 360(6384), 111-114.
[5] Anthony, D. W. (2013). Two IE phylogenies, three PIE migrations, and four kinds of steppe pastoralism. Вестник РГГУ. Серия: Филология. Вопросы языкового родства, (5), 1-21.
[6] Hodgson, N. (no date) THE MYSTERIOUS ABSENCE OF STABLES AT ROMAN CAVALRY FORTS [online] English Heritage. Available from: http://www.english-heritage.org.uk/learn/story-of-england/romans/absence-of-stables/ [Date accessed: 20 June 2018]
[7] VanDierendonck, M. C., & Goodwin, D. (2005). Social contact in horses: implications for human-horse interactions. The human-animal relationship. Forever and a day, 65.
[8] Wutke, S., Sandoval-Castellanos, E., Benecke, N., Döhle, H. J., Friederich, S., Gonzalez, J., ... & Morales-Muñiz, A. (2018). Decline of genetic diversity in ancient domestic stallions in Europe. Science advances, 4(4), eaap9691.
[9] Raudsepp, T., Santani, A., Wallner, B., Kata, S. R., Ren, C., Zhang, H. B., ... & Chowdhary, B. P. (2004). A detailed physical map of the horse Y chromosome. Proceedings of the National Academy of Sciences of the United States of America, 101(25), 9321-9326.
[10] Kopsida, E., Stergiakouli, E., Lynn, P. M., Wilkinson, L. S., & Davies, W. (2009). The role of the Y chromosome in brain function. Open neuroendocrinology journal (Online), 2, 20.
[11] Linnartz, L., & Meissner, R. (2014). Rewilding horses in Europe. Background and guidelines—a living document. Rewilding Europe, The Netherlands.
[12] Hockenhull, J., & Creighton, E. (2015). The day-to-day management of UK leisure horses and the prevalence of owner-reported stable-related and handling behaviour problems. Animal Welfare, 24, 29-36.
[13] Luthersson, N., Nielsen, K. H., Harris, P., & Parkin, T. D. H. (2009). Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark. Equine veterinary journal, 41(7), 625-630.
[14] Smith, S., Unpublished data. Horse Logic Ltd.
[15] Jansson, A., & Lindberg, J. E. (2012). A forage-only diet alters the metabolic response of horses in training. Animal: an international journal of animal bioscience, 6(12), 1939.