“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.