New research by Japanese scientists shows that the eye color of dog breeds has been naturally selected to make them appear… cuter.
Dogs were domesticated by humans around 20,000 years ago, selected from wolf individuals that displayed more approachable traits.
Most domestic dogs have dark brown eyes – (Photo: SCIENCE).
Behavioral scientist Akitsugu Komo from Teikyo University of Science (Japan) suggests that another important criterion for human selection of dogs for domestication is gentleness. The most specific expression of a dog’s gentleness is its eye color.
The research team gathered a large number of images from 33 different dog breeds, distributed across various countries, to conduct their survey. They used photo editing software to change the eye colors of dogs to shades of yellow, blue, and black, adjusting brightness levels as well.
Nearly 150 volunteers were asked to evaluate each dog based on characteristics such as friendliness, maturity, and intelligence, based on the photos.
The research team found that in photos of dogs with dark brown eyes, most volunteers rated their friendliness and sociability very high. Conversely, dogs with lighter-colored eyes were often rated as more aggressive.
Expert Akitsugu Komo explains that due to this psychological tendency, most domestic dogs currently have dark brown eyes, even though they have mostly evolved from wolves.
In contrast, the majority of wolves tend to have light-colored eyes, often yellow, with a sharper appearance. This trait helps wolves communicate more effectively in the wild and conveys a greater sense of power.
Currently, some domesticated dog breeds still retain light-colored eyes, primarily the Siberian Husky. These breeds also have a closer relationship with wolf species.
Veterinarian Jessica Hekman from the nonprofit organization Function Dog Collaborative believes that aside from natural selection, further research is needed to determine whether there are other reasons for the change in dogs’ eye color from light to dark during domestication.
However, according to the doctor, the hypothesis that humans prefer darker eye colors not only in dogs but also in other pets is quite convincing.
