New findings confirm that the “puppy eyes,” which evoke compassion, have evolved not only in domesticated dogs intended to attract humans, as scientists previously thought.
Reporters in Africa state that a recent study clarifying the evolutionary process of dogs dispels the belief that the sparkling, expressive eyes of puppies are solely a product of domestication.
A wild African dog in a wildlife sanctuary in Gauteng, South Africa. (Photo: Hong Minh/TTXVN).
This study also refutes a previous study from 2019 that proposed the hypothesis that dogs evolved highly expressive faces due to a long history of living alongside humans.
The new discovery, titled “Adaptation to Sociality in Facial Expression Muscles and Ears of African Wild Dogs” published in The Anatomical Record, asserts that the “puppy eyes” have not only evolved in domesticated dogs to attract humans, as scientists had previously believed.
Instead, the research indicates that other species within the dog family also possess the ability to create sad-looking eyes similar to those of domestic dogs.
Previous research published in 2019 and 2022 hypothesized that dogs developed new muscles around their eyes, specifically to facilitate more effective communication with humans.
However, the new study has dismissed this theory, finding that other dog species also have the capability to adapt similar muscles, allowing them to exhibit sad expressions.
African wild dogs have well-developed facial muscles similar to the “puppy eyes” expression in domestic dogs. (Photo: Hong Minh/TTXVN)
Previous studies compared the facial muscles of domestic dogs with those of the wolf (Canis lupus) to discover that dogs developed specialized muscles around their eyes to create more facial expressions.
Scientists concluded that these muscles may have evolved as dogs began to live more closely with humans, allowing them to mimic our facial expressions as a way to encourage us to take care of them.
In the new study, researchers dissected a specimen of the African wild dog (Lycaon pictus) that had died, provided by a zoo, and discovered that it also had similar “puppy eyes” muscles.
These facial muscles are not only present in wild dogs but have also been shown to develop equivalently to those seen in their domesticated counterparts.
Additionally, some facial muscles in African wild dogs seem to aid in the adept control of their large, floppy ears.
The researchers write in the study: “This morphology suggests that facial expressions through the eyes contribute to communication within packs in wild dogs and are not exclusive to domestic dogs.”
The lead author of the study, Heather Smith from Midwestern University (Illinois, USA), stated: “African wild dogs have well-developed facial muscles similar to the ‘puppy eyes’ expression in domestic dogs!”
Researchers believe that these eye muscles evolved to help African wild dogs coordinate and communicate while hunting on the open savannah.
Like wolves and their domesticated relatives, African wild dogs are highly social, living in groups of about 5 to 9 individuals.
Their highly expressive faces may allow them to create silent visual signals on the grasslands.
In the future, Smith and her team hope to examine the facial anatomy of other wild dog species, such as foxes, wolves, and Asian wild dogs, to see how well-developed their puppy eye muscles are.
This will help them gain a better understanding of how these species communicate and hunt, as well as assist researchers in determining whether this characteristic exists in species that are both social and visually oriented.
Adam Hartstone-Rose, a comparative morphologist at North Carolina State University, who was not involved in the study, commented: “This research confirms that not only do [wild dogs] have high sociality, but much of that social signaling may relate to visual signals.”
According to Hartstone-Rose, while wolves also live in closely-knit social groups, their facial muscles may not have evolved to be as robust as those of domestic dogs and African wild dogs because they rely less on visual communication.
Wolves hunt across various landscapes, including dense forests and mountainous areas, where individuals are more likely to be obstructed by rocks or trees while pursuing prey. As a result, they may have evolved to coordinate using more complex sounds or scent signals rather than visual signals.
