When Maureen and Jay Neitz adopted an adorable, fluffy black puppy in the late 1980s, they had no idea how important she would be in making new discoveries about vision.
They were just looking for a dog who was size-appropriate for the small apartment they lived in as UC Santa Barbara PhD candidates. Eventually, the teacup Poodle they named “Retina” helped the couple prove that dogs see much more than just black and white, and that dogs’ color vision is similar to that of the 8 percent of the human population who are red-green colorblind.
Ten million Americans, most of them male, are affected with red-green colorblindness, a genetic trait carried on the X chromosome. People with this condition can’t clearly see the difference between red and green. They often mistake green for white and red for brown or dark gray.
Colorblindness might not seem like a serious disability, but it causes unexpected, and sometimes tragic, problems for humans. For example, airline pilots must be able to differentiate between colors, which someone with red-green colorblindness can’t reliably do. Color vision is, of course, crucial in being able to discern if a traffic light is red or green. According to Don Peters, a consultant to the biotech industry who has red/green colorblindness, “Sodium vapor lights look a lot like red stoplights to me. It’s confusing to drive in an area with these lights, especially at night.” As a child, he had difficulties with color-related tasks: “I can still hear my teacher asking me why I colored the tree red. I couldn’t tell the difference.”
Colorblind people miss a lot of detail that people with normal color vision take for granted: they might not see the lines on a map, or lettering printed in colors that seem bright to those with normal vision but blend in for them. This can be dangerous when reading traffic signs or medication labels. Jay Neitz pointed out that children who are colorblind often have trouble in school, and can be mistakenly diagnosed with learning disabilities or ADHD; in spite of these potential problems, schools do not test students’ color vision.
The Neitzes established that dogs see shades of yellow, blue and gray. Other colors, such as red and green, appear faded or indistinct. Jay Neitz had an “aha” moment when Retina could not find her orange ball in a green lawn. “Sometimes the ball was right in front of her, but she would sniff around in the grass, trying to find it by smell. We realized that she simply couldn’t see it, even though it was obvious to us,” he said.
As UC Santa Barbara post-docs with degrees in biochemistry, molecular biology and biopsychology, the couple had access to a lab in which they could set up a testing area. “I realized that I had the opportunity to find out, once and for all, what kind of color vision dogs really have.” Jay built an apparatus that placed dogs in front of a screen with three lit panels. He trained the dogs to touch the screen with their noses when they saw a different shade. If the dog got it right, she would receive a cheese-flavored dog treat. In order to get the dog to touch the screen, Jay used peanut butter as an incentive. Once the dog mastered that part of the test, Jay no longer used the peanut butter.
Right away, Maureen and Jay discovered that, like people, dogs were good at figuring out shortcuts to getting a treat. In addition, “About 30 percent of the time, the dog made a lucky guess,” according to Maureen. The dogs’ attention spans were short, and on more than a few days, they just didn’t feel like doing the tests. “It took six months per dog to train them,” Maureen said. In addition to Retina, the Neitzes used two Italian Greyhounds; like Poodles, they are small, intelligent, easily trained dogs. “The dogs were treated very well,” Maureen said. “We had the utmost concern for their welfare.”
In 1989, Jay Neitz co-authored “Color vision in the dog,” which was published in the journal Visual Neuroscience; the research paper confirmed that dogs do, indeed see more than black and white. That led to a years-long search for a cure for colorblindness in humans.
Along the way, Jay heard from a diverse group of people interested in animal color vision. Game wardens asked him to create a color that hunters could use to spot each other but would be invisible to deer (“blaze orange” was the result) and, more recently, hundreds of people wanted to know what he thought of “The Dress,” a photo that went viral on the Internet featuring a dress that looked white and gold to some, blue and black to others.
Even the U.S. Army expressed an interest in the couple’s research. “They wanted to know if we could give dogs infrared vision so they could see lights used in locating bombs without alerting the enemy.” Jay joked that more people than he can count have sent him the “Far Side” cartoon showing a dog praying next to a bed, with a caption that reads “And please let Mom, Dad, Rex, Ginger, Tucker, me and all the rest of the family see color.”
Today, the Neitzes are both professors of ophthalmology and color vision researchers at the University of Washington. They continue their work in the field of color vision, but they don’t use dogs anymore. “Our dog study was done purely out of curiosity,” Maureen said. Jay added, “We demonstrated that color vision is much more complex than previously known, both in animals and in humans. Somewhere in our evolutionary past, humans developed the ability to see colors, which has helped us in many ways. One important advantage to having color vision is that it helps us determine whether a piece of food is ripe, and therefore good to eat. Humans were able to spot high-calorie food without putting out too much effort.”
In 2009, the Neitzes cured colorblindness in several male squirrel monkeys using gene therapy.
According to Maureen, “Male squirrel monkeys see only blue and yellow. Therefore, they make good subjects for color vision research.” The tests that the Neitzes developed during their original study with Retina and the two Greyhounds are now “vastly improved. We use a version of the Cambridge color test intended for human color vision testing, which Jay adapted so that it can be used on animals. It uses 16 colors, all of varying saturations.”
This more accurate test helps speed up color-vision research. The monkeys were given a human gene, which allowed them to see color the way we do. According to an article in Science, “The result raises questions about how the brain understands color, and it could eventually lead to gene-therapy treatments for colorblindness and other visual disorders in humans.”
As the Neitzes get closer to giving colorblind people normal color vision, it’s inspiring to think that a teacup Poodle trying to find her ball in the grass helped make this possible.