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.