Comparative anatomist Heather Smith and her team’s recent findings challenge the notion that “puppy-dog eyes” evolved uniquely for domestic dogs to communicate with humans. Published in The Anatomical Record on April 10, their study reveals that African wild dogs possess the same facial muscles associated with the infamous pleading expression found in domestic breeds.
The discovery, led by Smith from Midwestern University in Glendale, Arizona, sheds new light on the evolution of canine facial features. Anne Burrows, a biological anthropologist at Duquesne University and author of a previous study on canine eyebrow muscles, emphasizes the significance of this finding in understanding the origins of dogs.
In 2019, a study highlighted the pronounced presence of two muscles responsible for the “sad-sweet” puppy-dog stare in domestic breeds but nearly absent in wolves. This led Smith to question whether the highly social African wild dogs might also possess expressive brows.
African wild dogs, native to sub-Saharan Africa, face dwindling populations, making them challenging subjects for study but essential for conservation efforts. Smith’s team dissected a deceased African wild dog from the Phoenix Zoo and found that the muscles responsible for the puppy-dog expression were similar in size to those of domestic breeds.
The researchers suggest that these muscles evolved in African wild dogs as a communication strategy within their social structure. While vocal cues are known to play a role in organizing hunts and resource sharing, non-vocal strategies, such as facial expressions, have been overlooked until now.
Burrows speculates that more dog species may possess facial expression muscles than previously thought, raising questions about the evolutionary trajectory of these features. However, Muhammad Spocter, an anatomist at Des Moines University, urges caution in interpreting behavior solely based on anatomy, emphasizing the need for further research into the functional use of these muscles in wild dog populations.
