Peculiar gait of smooth-moving horses pinned on medieval genetic mutation
Long before plush leather seats and soundproof limousine cabins came along, the back of an ambling horse was considered the most comfortable ride in town. Scientists have now traced the origins of these smooth-moving creatures all the way back to medieval England, where the knights' penchant for the pleasant four-rhythm saunter and the selective breeding that followed instigated the global spread of the gaited horse.
Ambling horses are horses that travel faster than walking speed but slower than a canter, using one of numerous four-beat gaits to offer the rider a particularly smooth trip. Perhaps not so useful for heading into battle or the art of jousting, but you can imagine this agreeable amble lending itself quite well to long-haul journeys with armoured knights onboard.
Previous research had traced the horse's characteristic gait to a gene mutation affecting limb movement known as DMRT3, suitably called the gait keeper variant. Now, scientists from Berlin's Leibniz Institute for Zoo and Wildlife Research have studied ancient horse remains to pinpoint when exactly these gaited horses first trotted into the picture.
The sample studied included 90 horses stretching all the way back to before 3,500 BCE. The scientists combed through the DNA in search of the gait keeper variant, and found the genetic change in two English horses from the years 850 to 900 CE.
The gait keeper variant was found in no other horse remains from mainland Europe, but did pop up again in 10 out of 13 horses from Iceland, in the period between the ninth and eleventh century. This has led the researchers to the conclusion that after getting their start in England or the British Isles, ambling horses were taken across the seas and eventually, right across the globe.
"We detected the origin of ambling horses in medieval England," says Arne Ludwig of the Leibniz Institute for Zoo and Wildlife Research. "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 research was published in the journal Cell.
Source: Cell Press via Phys.org
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How is this ambling gait a mutation? Since there were natural horses with this gait that were selectively bred, starting with horses already having the gait, the gait was simply a not-often-expression of a gait already included in the gene pool.
Too much the word mutation is throw around and confuses those who would know factual science. Expression of rare, but already present gene pool characteristics is often used with the word "mutation to make nonsense, and non-scientific, statements such as, "flies adapted through mutation to become immune to DDT."
When DDT was introduced, it killed off MOST flies. However, there were some naturally immune flies also that were unaffected. Where 1000 flies might die from landing on a DDT "washed" window, every once in awhile an unaffected fly would e seen on that window. Hence the only ones left to breed were those that were immune. Therefore the previously, rarely-expressed, DDT-immune genome became the dominant one. No mutation - no new trait arising in all of "flydom." Just genetic expression of already extant genes.