Are or are not cats and dogs really color-blind? How do they know? –Jim Logan, Chicago
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You ever see a cat who could pick out a tie? Believe me, cats’ll wear things you wouldn’t put on a dog. But enough with the anecdotal evidence. Scientists usually test animal color sensitivity by trying to link color with food. One such experiment was conducted in 1915 by two scientists at the University of Colorado, J.C. DeVoss and Rose Ganson. They put fish in two jelly jars and then lined both with paper, one gray and one colored. If a cat picked the colored jar, it got to eat the fish. Nine cats, 18 months, and 100,000 tries later, the researchers established that cats picked the right jar only half the time–the level of pure chance. On the other hand, cats could readily distinguish between different shades of gray. Ergo, they said, cats are color-blind.
Less work has been done on dogs than on cats, but what there is suggests canine color sensitivity isn’t very good either. Much the same can be said for mammals in general, with the exception of primates. In contrast, some of your supposedly lower order creatures, such as fish, turtles, and especially birds, can distinguish color with ease. The fact that these primitive beasties should have more advanced visual abilities than their mammalian betters has always struck observers as a little odd; clearly the evolutionary progress of color vision has been more erratic than one might expect.
Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.
