Eyes languid, irresistible. How to ignore it when our dog asks us something looking at us like that there? In fact, we cannot, and now we also know why. And it is a reason linked precisely to communication. Wild animals – for example – communicate with each other even through small mimic movements that are difficult for us to grasp. The human being-instead-has lost a lot of this type of language by resorting to the word, he can say what he wants without being forced to read in the eyes. And he writes it no less than Konrad Lorenz in his famous book And the man met the dog.
Dogs and cats in the family: here’s how to communicate
by Irma D’Aria
Research just presented at the Experimental Biology (EB) 2022 meeting in Philadelphia April 2-5 reveals that humans have contributed, through centuries of selective breeding, to the ability of dogs to have eye-catching facial expressions for us. As already assumed by Eberhard Trumlera pupil of Lorenz, who continued his master’s studies on neoteny, man over the millennia would have selected dogs with neotenic characters, that is, closer to the appearance of puppies, with round, big snouts and languid eyes, because they stimulated tenderness and parental care.
I study
Anne Burrows, PhD, a professor in the physical therapy department at Rangos School of Health Sciences at Duquesne University in Pittsburgh and lead author of the study, says dogs are the only ones who can show their connection to humans through glance exchange. And the study findings provide a deeper understanding of the role of facial expressions in dog-human interactions and communication.
A story that begins long ago, about 33,000 years ago, when the species of wolves and dogs are supposed to have differentiated, that is, when man began to selectively breed wolves, which thus became the first species ever domesticated.
The study is based on facial muscles, or mimetics, a group of muscles just under the skin of the face that are controlled by the facial nerve. Their main function is the formation of facial expressions to express what one is feeling. In humans, these muscles contain fast-twitch myosin fibers that contract quickly but also tire quickly, so we are able to form facial expressions quickly but don’t hold them for long.
The selection made by man
By comparing myosin fibers in facial muscle samples from wolves and domestic dogs, the researchers found that both dogs and wolves have facial muscles dominated by fast-twitch fibers, but wolves have a higher percentage of slow-twitch fibers than wolves. to dogs. The latter intervene in longer and more controlled movements, which last longer. In the course of domestication, humans may have bred dogs based on facial expressions similar to his own, and over time their muscles may have evolved to become ‘faster’ and facilitate communication between dogs and humans.
All the fault of the fibers
According to the study, the percentage of fast twitch fibers in the dog samples ranged from 66 to 95 percent, and wolves averaged 25 percent. Slow twitch fiber rates in dogs averaged only 10% while wolves averaged 29%. Thus, the physiology of the facial muscles of dogs would be more similar to that of humans than that of wolves in terms of the distribution of myosin fibers. The fast twitch fibers allow for greater mobility and small movements such as a raised eyebrow and the short, powerful muscle contractions involved in barking. Slow twitch fibers are important for extended muscle movements such as wolves use when howling.
In previous research published in PNAS, the team found that dogs possess an additional mimetic muscle that is absent in wolves and contributes to the expression “puppy eyes”. It would be a muscle responsible for lifting the eyebrow, a movement that increases pedomorphosis, i.e. the preservation of childhood traits in adults (and let’s go back to Lorenz and Trumler’s neoteny) and is often seen in people when they are sad. Such an expression in dogs arouses tenderness and a desire for care. Probably, the eyebrows of dogs are the result of a selection based on man’s own preferences. Less natural, perhaps. But we also like them that way.