Last weekend my friend Kevin bagged going to see a late movie with a group of us because he’d promised a woman he’d arrive at her apartment at 10:30 to spend the night. Not for amorous pursuits, he insisted, but because she was terrified of being alone at night. He explained that she’d just moved to the ground floor of a new building after years of living in high-rises, and kept hearing noises in the alley that sent her imagination flying and made it impossible to sleep.
Best of Chicago voting is live now. Vote for your favorites »
A couple of years ago I was camping alone in the wilds of Theodore Roosevelt National Park in western North Dakota. Bleak and dry, with misshapen rock outcroppings, the landscape’s strangeness was exacerbated by the dark. When I turned off my small flashlight and tried to sleep, the little bluestem grass scratched against the nylon wall of the tent, sounding as though someone or something was trying to get in. I had the clear sense that I absolutely did not belong there. By midnight I was so agitated I packed up my equipment in the dark and ran across the badlands for my car, which I drove to a motel on Interstate 94.
But by night cats rule. Their pupils dilate dramatically, letting any available light flow freely into their eyes. And once the light enters the retina it falls on a great bounty of rods, the photoreceptor cells most efficient at processing images in low light. Cats possess another great trick: our rods also catch light entering our retinas, but in night denizens either the retina or the choroid (the layer right next to the retina) has a mirrorlike adaptation that bounces the light, giving the rods a second chance to absorb it. (It’s this mirror that causes animals’ eyes to illuminate when caught in car headlights.)
I keep thinking of the final part of The Silence of the Lambs, where Jodie Foster tries to capture the serial killer in a horrid pitch-black cellar. The detail that made the scene so memorable was that the psychopath puts on infrared night-vision glasses that enable him to watch her when she can’t see him. Ordinarily the two humans would be equally blind in the dark, but in this scene the killer has an unsettling advantage–just as if he were a tiger and Jodie a lost villager.
