“All puppies are cute,” explains Clive Wynne, the head of Arizona State University’s canine-science laboratory. “But not all puppies are equally cute.” Indeed, breeders have long found that puppies become their cutest selves at the eight-week mark; any older, and some breeders offer a discount to bolster would-be owners’ weakened desire. Such fine-tuned preferences might seem arbitrary, even cruel. But recent research indicates that peak puppy cuteness serves important purposes—and might play a fundamental role in binding dog and owner together.
In a study published this spring, Wynne and his colleagues sought to pin down, scientifically, the timeline of puppy cuteness. Their finding largely matched that of breeders: People consistently rated dogs most attractive when they were six to eight weeks old. This age, Wynne says, coincides with a crucial developmental milestone: Mother dogs stop nursing their young around the eighth week, after which pups rely on humans for survival. (Puppies without human caretakers face mortality rates of up to 95 percent in their first year of life.) Peak cuteness, then, is no accident—at exactly the moment when our intervention matters most, puppies become irresistible to us.
It doesn’t hurt that humans seem to be especially vulnerable to cute things. Research dating back to the 1940s shows that virtually any creature with babylike features—large eyes, a bulging forehead, short limbs—is capable of drawing our affection, from the unsurprising (seals, koalas) to the odd (axolotls, a type of salamander) to the inanimate (Mickey Mouse). But canine cuteness is uniquely human-directed, and its strategic deployment is not confined to puppies. In a 2017 study of dogs ages one to 12, psychologists in the United Kingdom showed that people’s pets were significantly more likely to raise their brows and stick out their tongue when humans were looking at them, visual cues that lend grown canines a puppyish air. Other research makes clear just why dogs seek to command our attention in this way. Oxytocin, the so-called love hormone, has been found to surge in dogs and their owners after they look in each other’s eyes—initiating the same feedback loop that exists between human mothers and their babies. In other words, the more dogs get us to look at them, the more tightly bonded to them we grow.
Born blind and basically deaf, puppies aren’t interactive in their first weeks of life, and Wynne notes that many people find animals in this stage alien and unappealing. A recent study focused on humans showed that, similar to six-week-old puppies, six-month-old babies are seen as significantly cuter than newborns.
Which brings us to the final purpose of peak cuteness: to make up for newborn ugliness. As the psychologists Gary Sherman and Jonathan Haidt have proposed, the delayed onset of cuteness in human babies offers benefits far beyond kicking our caretaking instinct into overdrive—it also prompts a flood of social interactions, such as petting, playing, and baby-talking. These acts are developmentally crucial to puppies as well, but they can’t be carried out very effectively with the extremely young. And so “one is not born cute,” Sherman and Haidt conclude. “One becomes cute.”
This article appears in the November 2018 print edition with the headline “Survival of the Cutest.”