Alfie and Me: What Owls Know, What Humans Believe

by Carl Safina

call light strikes our eyes only; none reaches our brain. In the back of an eye, the retina consists of several layers of differing cells with differing functions. When particular wavelengths strike, these cells create impulses channeled to the optic nerve. The optic nerve carries not the wavelengths—not the “light”—but only the electrochemical signals. Next, from the encrypted encoding that the optic nerve delivers, specialized sections of that amalgamated collection of neurons and functions that we call the “brain” construct a three-dimensional facsimile of the world in space. These illusions, we experience as light and sight. The images are so convincing, we feel that we are seeing out. We use this grand illusion to navigate at high speed, to catch or strike objects in motion, to detect someone we might one day love, or even to store a memory, a retrievable reconstructable imagined image of something fond or feared. Human optic nerves do not encode impulses from the infrared or ultraviolet wavelengths adjacent to humanly visible light, but some other animals see these colors exquisitely well. Human difficulty seeing at night, and the sensation of “darkness” itself, results from particular limitations of our primate optic system, limits easily breached by the optic systems of nocturnal beings such as owls. Plants, lacking nervous systems and visual receptors as we understand them in animals, almost certainly have no ability at all to perceive sensations of light, despite...