"I was walking down Fifth Avenue next to the park once,” says Robert Voss, curator of mammalogy at the American Museum of Natural History, “and there were a bunch of grade-school girls looking down at the sidewalk, going, ‘Eww! Rats! Eww!’ What they were actually looking at were baby squirrels, which haven’t developed furry tails yet, that had fallen out of a tree. I told them, and they immediately said, ‘Aww, squirrels!’ ” New York’s parks’ ubiquitous woodland guests make our urban existence a little warmer—and, of course, a whole lot fuzzier. What makes squirrels so appealing to the teenage girl inside all of us? Foremost, obviously, is the tail. For the squirrel, the cuteness value of its tail is just a happy coincidence; big tails are useful for tasks like keeping balance on narrow tree limbs, acting as a blanket during sleep, and drawing airborne predators’ attention away from more vulnerable areas of the body (this being particularly important for the Central Park squirrel, hunted as it is by the celebrity red-tailed hawk). Less obviously, squirrels are diurnal, sleeping at night—so, unlike certain other small foraging rodents, they’re not encountered during “times of the daily cycle when humans feel threatened,” as Voss puts it. They also appeal to mankind’s primitive urge to not kill. “Humans are programmed to turn off aggressive tendencies when they’re looking at an immature human being,” Voss says. Babies’ eyes are larger relative to the rest of their body, while their facial features are smaller, which means that animals with big eyes and small noses, like squirrels, inspire instinctive mellowness. Sometimes, evolutionary biology is just so adorable.