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The Straight Dope



Are or are not cats and dogs really color-blind? How do they know? --Jim Logan, Chicago

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.

Doubts about this conclusion arose some years later, however. Cats have cones as well as rod-type vision receptors in their retinas, and cones have long been associated with color vision in humans. Neurologists who wired feline brains up with electrodes discovered that, on laboratory instruments at least, cats responded to light of different wavelengths, which is to say, color. So researchers went back for another round of fish experiments. Finally, in the 1960s, they managed to teach the cats to discriminate between colors. But it took some doing. One group found it took their cats between 1,350 and 1,750 tries before they got the hang of it.

From this one might deduce one of two things: either cats are real stupid, a proposition Cecil has no trouble buying, or else they just don't give a flying frock about color. Most cat scholars have opted for choice #2, saying that the ability to distinguish colors is obviously of no importance to cats and hence not something they learn readily.

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.

It being spring and all, we would like to know what the connection is between Easter and rabbits, and for that matter between rabbits and eggs. My uncle told me that when the west was in the process of being won, trappers knew it was Easter when the first rabbits of the season appeared. That explains things locally, I guess, but does it mean they don't have chocolate Easter bunnies in Paris? --Ed Young, E. 52nd

I realize we're getting to this one a little late, gang, but I feel the Easter bunny is one of those subjects with year-round relevance. Many stories have been told to explain the EB's origin. There's the one about the rich lady in medieval times who hid eggs around the backyard as a springtime treat for the neighborhood urchins. Seeing a wild hare or two bounding about the premises and then finding a mysterious egg a short time later, the kids supposedly concluded that the former had laid the latter. Charming, sure, but woefully lacking in explanatory power. In reality the association of Easter, eggs, and rabbits dates back to the early Christian era, when the celebration of the Resurrection became conflated with traditional spring fertility rites. (Indeed, in the eighth century, the Venerable Bede speculated that the word "Easter" was originally the name of an Anglo-Saxon goddess of spring/dawn/fertility, although this has since been disputed.) Eggs and rabbits, for obvious reasons, are fertility symbols of long standing. Once again, we find that one of our sacred days is tainted with lust. Incidentally, the usual symbol in Europe, where this all got started, is actually the hare. The relatively hare-starved U.S. was obliged to substitute the smaller and infinitely cuter bunny rabbit.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.

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