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A small dusky brown horse high-steps through the snow. A dusting of powder accents his coat like sifted sugar. I crouch in the saddle in a thick snowsuit, gathering the reins as we trek into a blinding white wilderness about 30 minutes outside of Iceland’s capital city Reykjavík. Though the temperature dips into the 20s Fahrenheit, he has broken a sweat from the ride.
The horse’s name is Fjalar and he was born and raised to survive the seasons in Iceland. This land of fire and ice has shaped his genetics over 1,100 years. He stands just under 14 hands tall at his shoulders, or 55 inches. His fur is thick enough to obscure my fingers when I press my hand to his side. He can easily stomach grasses and hay poor in nutrients.
Fjalar also can do something most other horses in the world cannot. In addition to a traditional walk, trot, canter and gallop, Fjalar can tölt and he can perform a flying pace, or skeið—two gaits unique to Icelandic horses.
Equestrians talk about gaits in rhythmic terms. A tölt is a four-beat movement in which the horse always has one foot on the ground in a specific sequence. A pace has two beats, in which the horse moves the front and back leg on one side simultaneously. During one phase, all four feet are off the ground. Pacing horses can reach up to 30 miles per hour. Both gaits can make it look as though the horse were ice skating, carrying a rider seamlessly across a plain, and some Icelanders race while carrying full beer steins.
In a recently defended dissertation, researcher Heiðrún Sigur∂ardóttir was able to identify for the first time two genes Icelandic horses have that affect these gaits, in addition to the one that had previously been identified, which could help shape future breeding decisions. Her genetic analyses also showed that centuries of inbreeding on the island have not harmed the genetic diversity in the breed and so continue to be sustainable.
The two new genes Sigur∂ardóttir identified that play a role in an Icelandic horse’s special gaits are expressed in neural tissue: the STAU2 gene, which was also shown to influence the quality of a horse’s trotting and galloping, and the RELN gene, which impacts the quality of tölt, trot, canter, and gallop, and may influence the trainability and precocity of young horses. In addition, Sigur∂ardóttir showed that these two genes together with a previously identified DMRT3 “gait keeper” mutation have additive and compensatory effects on an Icelandic horse’s ability to pace. Previous research has shown that when Icelandic horses do not have a specific DMRT3 mutation, that these horses are unable to “pace,” and she found this was so even when the horses had the other two genetic markers linked to strong pacing abilities.
Some Icelanders race while carrying full beer steins.
“These are highly complex traits that we are looking at, which makes them interesting, but difficult,” she says. “It’s like looking for a needle in a haystack.”
To identify the genes, Sigur∂ardóttir pulled pedigree data from Iceland’s studbook, developed in 1923, which describes the lineages, gaits, and other characteristics of individual Icelandic horses, and an international WorldFengur database that began tracking more than 560,000 individual Icelandic horses, dead and alive, in 2000. She then pulled hair and blood samples from individual living horses, applying genome wide association study analysis to genetic data and pace and gait “scores” of 380 of them and whole genome sequence analysis and pace and gait scores to 39 horses.
Early people in Iceland needed horses that could run for miles without tiring. More than 1,000 years ago, the newly discovered land was rugged and unforgiving, a world of volcanoes, rushing rivers, and winter storms with wind gusts that could knock over a grown adult. The only reliable forms of transportation on land were the horses brought by Norse and other settlers—including Mongolian and Norwegian Fjords, both stocky and hardy breeds.
After noticing certain horses moving in ways that made traveling smoother, they took the foals and started breeding for what became the pace and the tölt. Though other breeds in the world—such as the Paso Fino and Tennessee Walking Horse—are smooth movers, they cannot perform the tölt and some claim their pacing gaits are less graceful or quick than that of the Icelandic horse.
Since those early days, Icelandic horses have not incorporated new breeds into their lineage. Foreign horses are not allowed into Iceland, and once an Icelandic horse leaves the nation, they are not allowed to return. Icelandic horses are not vaccinated because of their isolation.
Fjalar seems to know he belongs to a special breed. He passes one horse, then another to take the lead. Snow flies from his hooves as he moves out across the snowy avenue. But he stays with his herd. It’s easier to keep warm in a group, to break through the snow, to keep his bearings in this stunning monochromatic landscape where his ancestors once roamed. 
Lead image: Nick Fox / Shutterstock
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