The piercing blue gaze of a husky is a big part of the charm of the breed — one that leaves hearts melting left and right whenever these lovable wolf-like canines make an appearance.
But no one has been able to figure out why these Arctic “good boys” are born with pale-blue eyes — a feature shared by very few dog breeds, according to Nuzzle. Nuzzle lists only the Siberian Husky, Australian Shepherd, Border Collie, Dalmatian, and Shetland Sheepdog as having this distinctive eye color.
Enter Cornell University scholars, who are finally beginning to unravel the mystery, reports Inverse.
In a new study published yesterday in the journal PLOS Genetics, a team of scientists from the prestigious New York university ventures an explanation for those cerulean eyes that give Siberian Huskies their wild magnetism — aside from their sled-pulling and prey-hunting abilities, that is.
Their findings suggest that this particular dog breed may owe its blue eye color to a specific chromosome dubbed canine chromosome 18. This DNA molecule is located near a special gene called ALX4, which previous studies have shown controls eye development and pigmentation in mammals.
To get to the bottom of things, the scientists partnered up with Embark Veterinary, Inc., a consumer genetics testing company similar to 23andMe — but which performs DNA analysis on dogs.
As Embark senior scientist Aaron Sams explains, the goal of the company is to provide dog owners with “useful and interesting information” about their pet’s genome by conducting genetic tests that could one day “end preventable diseases in dogs.”
“With that data we can conduct studies like these to better understand the role of genetics and the environment in the development of diseases in dogs, thereby improving the lives of both dogs and their owners.”
Aside from gathering DNA data to establish the animal’s genealogy, breed profile, and risk of hereditary conditions, Embark Veterinary also analyzes the genetics for specific physical features, such as coat color, body size, and agility performance, notes Discover Magazine.
For the purposes of this study, the team took a close look at what gives Siberian Huskies their blue eye color by investigating the genetic data of 6,070 purebred and mixed-breed pooches, 156 of which had solid blue eyes or partially blue eyes.
After examining more than 200,000 genetic markers to see how often they led to blue eyes versus brown eyes, the scientists finally caught a break.
“Most of the time there wasn’t a correlation at all, but in this one part on chromosome 18, we found a whole bunch… in dogs that had blue eyes,” said Adam Boyko, Embark co-founder and a genomics researcher at Cornell University.
Scientists Finally Figured Out Why Siberian Huskies Have Ice-Blue Eyes: https://t.co/zdanZFUCxA
— Inverse (@inversedotcom) October 4, 2018
The research uncovered that Siberian Huskies have this specific chromosome expressed in duplicate, which might explain why this particular breed can have blue eyes regardless of how they test for the merle gene — a gene that randomly dilutes pigmentation in dogs, causing their iris to turn blue.
The same discovery was made in the case of tri-colored Australian Shepherds, who also possess a duplication in the canine chromosome 18.
“Our hypothesis, which still needs to be tested, is that this duplication may alter expression of ALX4, which may lead to repression of genes involved in eye pigmentation,” said Sams.
As he told Newsweek, dogs that carry a single copy of this mutation are usually born with blue eyes. Nevertheless, in some instances the mutation fails to lead to blue eye pigmentation, which suggests that other factors — either genetic or environmental — are at play.
“This is the first discovery that’s been made this way outside of humans,” said Boyko.
While the researchers still have a way to go before this mechanism is completely understood, Sams believes that these findings could one day lead to a scenario in which dog breeders get to choose the eye color of their new litters.