The Science Behind Those Big Puppy Eyes | Smart News


The muscles that enable “puppy eyes” in domestic dogs aren’t developed in wolves, suggesting the adorable look evolved to captivate humans. (Photo: author’s dog, Smoky.)
Courtesy of Elizabeth Gamillo

When a canine companion wants an extra treat, one look from those endearing puppy eyes is all it takes. Now, scientists suggest that domesticated dogs may have evolved extra facial muscles to woo people with their adorable expressions.

Humans may have contributed to the comforting look through thousands of years of selective breeding for anime faces, a statement says. Presented at the Experimental Biology 2022 meeting in Philadelphia, the preliminary research offers a deeper look at how dogs communicate with us.

“Dogs are truly unique from all other pets in that they exchange a bond with their humans. They are truly our companions,” says study author Madisen Omstead, a biologist at the University Duquesne of Pittsburgh, to Chen Ly at new scientist. “They demonstrate it through their gaze on each other – that ‘puppy eye’ gaze they give us.”

In humans, tiny muscles around our eyes and mouth are responsible for quick little facial expressions like raising an eyebrow, reports Robyn White for Newsweek. Our so-called mimetic muscles are powered by fast-twitch myosin fibers that tire quickly, which is why we can’t hold them in these expressions for very long, a statement explains. Other muscles contain slow-twitch myosin fibers used for long, controlled movements.

For the experiment, the research team quantified the number of wolf and dog fast and slow twitch fibers in their mimetic muscles, new scientist reports. Fast-twitch fibers made up 66-95% of fast-twitch fibers, while wolves make up an average of 25%, reports Tom Metcalfe for NBC News. The facial muscles of wolves were dominated by slow-twitch muscles, which they could use for prolonged movements like howls.

Like humans, dogs have a higher percentage of fast twitch fibers in their facial muscles, Newsweek reports. As dogs split from their wolf ancestors 33,000 years ago, the need for slow-twitch muscles may have diminished and their facial expressions have become more captivating and familiar to people.

The fast-twitch muscles around dogs’ mouths may have evolved to produce the sharp, snappy barks that pets use to communicate with their humans today, reports Anna Salleh for ABC News in Australia. Dogs may bark at their humans to play, get our attention, protect their territory, or warn us.

“It was part of the process of domestication in one way or another – whether humans consciously chose which dogs barked or whether it was a by-product of domestication,” explains the author of the study Anne Burrows, biological anthropologist, to ABC News.

Scientists plan to further study how barking developed in dogs and why humans were able to select for this trait during the domestication process. The team also plans to study whether domestication shaped the mimetic muscles of other mammals, Burrows says. Newsweek.


Comments are closed.