29/06/2024
Wow!
DOMESTICATION LIMITS DOGS' EMOTIONAL FACIAL EXPRESSIONS COMPARED TO WOLVES
A new research paper by Dr Sean Twiss and Elena Hobkirk (2024, University of Durham) has identified the first measurable evidence that domestic dogs are limited in their ability to produce the same emotional expressions as their wolf ancestors (link in comments). Due to the vast array of domestic breeds in circulation, breed morphologies ( cephalic index) were also considered. An interesting technique warranted application for this research; the use of slow-motion footage to read wolf facial expressions, compared to domestic dogs, whose expressions could be detected without slow-motion technology.
This study examines the impact of domestication on the ability of dogs to convey emotions through facial expressions, comparing them with their wolf ancestors, and concluding that selective breeding has altered the facial morphologies of dogs, limiting their capacity to produce the same range of affective facial expressions as wolves. By analysing facial movements in wolves during social interactions, researchers identified nine distinct emotional states. However, dogs, especially those with non-wolf-like features, showed reduced predictive power for these states, often confusing positive and negative emotions. This limitation in facial communication can affect both dog-human , and dog- dog interactions, though they suggest dogs likely compensate with vocalisations . The findings highlight the social communicative limitations bred into domestic dogs and emphasise the more complex emotional expressions of wolves. Breeds with brachycephalic faces or flopped or semi-flopped ears, such as in bully breeds were identified as being the most limited in their expression.
A 'confusion matrix' was used to map data, showing the affective state that caused the most confusion in dog facial expressions was fear, with 31% confusion between fear and anger. The affective state that caused the least confusion in dog facial expressions was friendly, with a precision of 75%. Interesting differences that were observed: wolves used the 'ear forward' movement in the context of anger 30% of the time, and domestic dogs only 12%. Bracycephalic and Mesocephalic breeds traits were most associated with confusion. The key conclusion, however, was the substantial confusion between positive and negative affective states for domestic dogs, with fear being misread as friendly, especially relevant in dog- human interactions.
The data suggests that domestic dogs only in part produce facial expressions with a limited range of affective states compared to wolves. The muscles around the lips, muzzle, and noses of both brachycephalic and mesocephalic dogs have much less space to develop and are too small to produce the full range of movements required for robust facial expressions.
The impact on domestic dog welfare due to these limitations cannot be understated, but the consideration of the human impact due to dog bites is equally important. The constraints on dog-dog communication issues are significant also, as it is well established that the risk of conflicts between dogs can increase due to certain morphological differences. Many dogs might display fear when encountering dogs that resemble wolves, or conversely, some dogs might play more vocally or animatedly with certain breeds.
Even for dog professionals, it can be challenging trying to read body language or affective states in some dogs, especially those with more neotenised features. The increase in 'doodle' breeds in populations has had an impact also, as due to their fur, muscle movements, especially around the face, can be challenging to spot. There are also impacts to consider in multi-breed dog households, day care facilities, training environments and much more.
Some examples below:
Bracycephalic breeds: American Bulldog, Boxer, Mastiff, Pug, French Bulldog, SharPei, Cane Corso
Dolichocephalic breeds: Schnauzer, Greyhound, Saluki, German Shepherd, Doberman, Standard Poodle, Many terriers, [Wolves , Coyotes]
Mesocephalic breeds: Border Collie, Belgian Malinois, Most Spaniels, Retrievers, Husky, Beagles, Setters, Vizla [ African wild dog]
The study also highlights the need to better understand vocalisations, and as this might well be breed dependent and the importance of secondary communication features observing body movements and olfaction (particularly in the cases of dog-dog). i.e dogs struggling to read the language of another might pause more frequently to smell the other.
The need for educational photos and video footage on affective states across breeds has become really important.
Opportunities for safe encounters between breed demographics, and the ethical use of 'helper' dogs, which many dog professionals are now utilising , are crucial in improving the welfare of both dogs and humans.
Boo Blackhurst, CDBC
