Puppy dog eyes DO exist! Dogs are seen as more friendly and less threatening if they have dark eyes, study finds

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  • Dogs with darker-coloured eyes are perceived as friendlier and less threatening
  • And experts say that humans may have driven their popularity

By Xantha Leatham Deputy Science Editor For The Daily Mail

Published: | Updated:

Try as you might, it can seem almost impossible to say no to your puppy when they gaze at you imploringly with their big, brown eyes.

Now, a study has found that dogs with darker-coloured eyes are perceived as friendlier and less threatening. 

And experts say that humans may have driven their popularity.

All modern dogs are descendants of wolves and became ‘man’s best friend’ through over thousands of years of domestication.

The most common eye colour for wolves is yellow, and scientists wanted to figure out if humans may have had an influence on their descendants’ eye colour today.

Dogs with lighter eyes are seen as less friendly

Experts have found that dogs with darker-coloured eyes are perceived as friendlier and less threatening – and humans may have driven their popularity

The team, from Teiko University of Science in Japan, collected 22 images of grey wolves and 81 pictures of domestic dogs from 35 different breeds. 

They found that the irises of dogs were much darker compared to those of wolves – and were more likely to be brown compared to yellow.

They then collected 12 images of dogs including Labrador Retrievers, Vizslas and Welsh Corgis, and ‘recoloured’ their eyes to either be dark or yellow.

When they asked 76 participants to rate the photos, they found that dogs with darker eyes were seen as friendlier and less threatening than the same dogs with lighter-coloured eyes.

Researcher Dr Akitsugu Konno said: ‘We speculate that a darker iris makes it more difficult to distinguish the size of the pupil and thus gives the illusion of a large pupil, which is associated with our perception of being more infant-like.

The researchers collected 12 images of dogs including Labrador Retrievers, Vizslas and Welsh Corgis, and 'recoloured' their eyes to either be dark or yellow

The researchers collected 12 images of dogs including Labrador Retrievers, Vizslas and Welsh Corgis, and ‘recoloured’ their eyes to either be dark or yellow

‘Human studies demonstrate that humans evaluate those with dilating pupils as more friendly, attractive and trustworthy.’

The researchers said darker eyes may elicit a ‘caregiving’ response from humans, which drove the evolution of this trait in domesticated dogs.

Writing in the journal Royal Society Open Science, they added: ‘In conclusion, our results suggest that the iris colour of dogs is darker than that of wolves, and that dark eyes of dogs positively affect human perception toward dogs.

‘Dogs with dark eyes may have evolved by acquiring a facial trait that sends a non-threatening gaze signal to humans.’

DOGS WERE FIRST DOMESTICATED SOME 20,000–40,000 YEARS AGO

A genetic analysis of the world’s oldest known dog remains revealed that dogs were domesticated in a single event by humans living in Eurasia, around 20,000 to 40,000 years ago.

Dr Krishna Veeramah, an assistant professor in evolution at Stony Brook University, told MailOnline: ‘The process of dog domestication would have been a very complex process, involving a number of generations where signature dog traits evolved gradually.

‘The current hypothesis is that the domestication of dogs likely arose passively, with a population of wolves somewhere in the world living on the outskirts of hunter-gatherer camps feeding off refuse created by the humans.

‘Those wolves that were tamer and less aggressive would have been more successful at this, and while the humans did not initially gain any kind of benefit from this process, over time they would have developed some kind of symbiotic [mutually beneficial] relationship with these animals, eventually evolving into the dogs we see today.’