I.Q. in man, maze skills in rats, chickens who play baseball, chimps who pile the boxes to reach a banana, the quicker learning and longer retention of cattle as compared to horses, the circus dog who will walk grotesquely on his front feet—all these things are small illuminations in a great darkness. Too often we confuse some adaptive instinct with reasoning power. There is, for example, one small and enchanting crab in tropical waters which carefully plucks bits of marine weed and, with all the care of a woman doing her own hair, plants these living bits atop his shell so as to make himself less noticeable in his environment. The hermit crab, growing too large for his mobile home shell, will crawl from empty shell to empty shell, using his claws to measure the opening, as businesslike and thoughtful as any carpenter measuring for a shelf. Finding one a suitable degree larger, he will take a long and careful look around before, with frantic haste, he hoists his soft nether portions out of the old home and slips them into the new.
