This Is the Age That Puppies Are Cutest, According to Science

Researchers have revealed the point at which puppies appear the most attractive to us—and the discovery could shine a light on how man's best friend has evolved to rely on human care.

For a new study published in the journal Anthrozoos: A Multidisciplinary Journal of the Interactions of People and Animals, researchers from Arizona State University and the University of Florida found that puppies' cuteness peaks at around eight weeks—which is roughly the time at which their mothers stop weaning them, allowing them to fend for themselves.

The scientists were interested in investigating whether there was any link between the age at which weaning stops—and, therefore, when the puppies are most vulnerable—and their attractiveness to people.

So, they devised a study in which they showed 51 images of puppies at different ages—ranging from between a few weeks old and young adulthood—to 51 participants, asking them to rank the level of attractiveness of the dogs in each picture. The breeds used were Jack Russell terriers, cane corsos and white shepherds.

The team found that the participants rated the puppies as least attractive at birth, before the scores steadily rose until the peak of eight weeks. After this point, the attractiveness scores began declining again and leveling off.

Additionally, there was a slight difference between the breeds as well, with the cane corsos appearing most attractive at 6.3 weeks of age on average, while the Jack Russells and the white shepherds appeared the cutest at 7.7 weeks 8.3 weeks respectively.

"It came out exactly as I'd hoped it would—that there is indeed an optimal age of maximum cuteness, and that age does line up pretty closely with the age at which mothers wean their pups," professor Clive Wynne from Arizona State University said in a statement.

The results may indicate that the age of this "peak cuteness" are a sign of the age-old relationship between humans and dogs, according to Wynne, although this link has not yet been tested.

Puppies appear the most attractive to humans around the same time as their mothers stop weaning them, according to new research. Amanda Edwards/Getty Images for Discovery Communications

"This could be a signal coming through to us of how dogs have evolved to rely on human care," he said. "This could be dogs showing us how the bond between human and dog is not just something that we find immensely satisfying in our lives. But for them, it's the absolute bedrock of their existence. That being able to connect with us, to find an emotional hook with us is what actually makes their lives possible."

In other words, dogs' ability to form intimate, strong and affectionate bonds with humans—helped by their peak cuteness at the age that they stop weaning—is essential to the survival of their species.

This is not the first time that science has uncovered evidence of the extraordinary relationship between dogs and humans. For example, a 2017 study, published in the journal Scientific Reports, found that dogs make more facial expressions when humans are looking at them.