Here is why most dogs have brown eyes

Unlike the light yellowish eyes of wolves, dogs’ eyes are usually brownish in colour. And there are good reasons for this.

You have probably noticed that most dogs have brown eyes. This is no coincidence – but until now there was little to no explanation.

In a study published by the Royal Society Open Science, the authors point out that dogs’ eye colour changes after domestication due to a very important evolutionary purpose. The Japanese research team that carried out the studies concluded that the reason, or more precisely the purpose of this is the dogs’ relationship with humans.

The reason is that warm, brown eyes are less intimidating than the flashing bright eyes of wolves. Because of this at the beginning of domestication darker-eyed pups were more likely to be chosen. This led to more dogs with warm-coloured, brown eyes. Breeders tend to find it desirable, so they breed for this attribute in around 92% of dog breeds.

This is not the only change domestication has brought. Dogs have changed in size, shape, the way they communicate with humans, and even their facial features. All to make coexistence between our two species smoother and easier.

The scope could be widened

The study leaves an important question open, given that it was conducted only with Japanese people. (Participants were shown a picture of the same dog, once with lighter, yellowish eyes, and the second time with brown eyes. They had to decide which one they thought looked friendlier.) So the question stands whether the researchers would get similar results worldwide. However, the research team believes there is a universal preference for brown eyes.