The genetic mutation responsible for the smooth movement seen in the gaited breeds originated in medieval England, according to an international team of researchers.
The so-called gait-keeper gene then spread rapidly around the globe, as riders increasingly coveted the comfortable ride.
Today, breeds with a high frequency of the mutation – greater than 50 percent – are either classified as gaited or bred for harness racing.
Earlier studies had traced the distinctive ambling gaits seen in some breeds today to a single “typo” in a gene involved in co-ordinated limb movement.
During such ambling gaits, the horse has at least one foot on the ground, meaning that the vertical movement of the rider is minimal.
A striking example is the ability of some horse to perform additional gaits other than the common walk, trot and gallop. Those could be four-beat ambling gaits, which are particularly smooth and comfortable for the rider, or pacing, used mainly in racing. Breeds such as the Icelandic horse and the Paso Fino are renowned for their ambling gaits.
In the latest study, researchers genetically examined historic horse remains, finding that gaitedness in horses made its first appearance in medieval England around 850 AD and rapidly spread from there.
“We detected the origin of ambling horses in medieval England,” said Arne Ludwig, of the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany.
“Vikings took these horses and brought them to Iceland and bred them there. Later, ambling horses were distributed from England or Iceland all around the world.”
The researchers assembled DNA samples, including 90 horses going back to pre-domestic times, before 3500 BC, through to the Middle Ages. They examined the DNA in search of that earlier identified gait-keeper variant in a gene known as DMRT3.
The researchers detected the tell-tale genetic change in two English horses from 850 to 900 AD and in 10 out of 13 individuals from Iceland dating to the 9th to 11th century. The gait keeper variant was absent in all of the tested horse remains from mainland Europe.
Ludwig and colleagues, writing in the journal Current Biology, said the discovery that gaited horses were present in Iceland so long ago strongly suggested that Norse people from Denmark and South Sweden took them from the British Isles to Iceland.
“Considering the high frequency of the ambling allele in early Icelandic horses, we believe that Norse settlers selected for this comfortable mode of horse riding soon after arrival,” the researchers wrote.
“The absence of the allele in samples from continental Europe (including Scandinavia) at this time implies that ambling horses may have spread from Iceland and maybe also the British Isles across the continent at a later date.”
Ludwig said they were surprised that the gait-keeper variant had not arisen sooner, mainly because the trait now occurred so widely in horses all around the world. But, he noted, with strong selection in the course of breeding domesticated animals, “everything can happen very fast”.
Horseback riding is the most fundamental use of domestic horses and has had a huge influence on the development of human societies for millennia. Over time, riding techniques and the style of riding improved. Therefore, horses with the ability to perform comfortable gaits became highly valued by humans, especially for long distance travel.
The researchers said there were still many open questions about how human preferences changed over time and how those shifts influenced horses.
The researchers said they were also interested in how those past events continued to influence domesticated animals and animal breeding today.
Researchers in an earlier study have shown the extent to which the gene had spread. The team analyzed 4396 horses from 141 breeds around the world and found that the gait-keeper mutation was spread across Eurasia from Japan in the East, to the British Isles in the West, on Iceland, in both South and North America, and also in breeds from South Africa.
It was present in 68 of the 141 genotyped horse breeds at a frequency ranging from 1 percent to 100 per cent, distributed worldwide.
Current Biology, Wutke et al.: “The origin of ambling horses“.
The abstract can be read here.