Man is the Measure by Reuben Abel

Author:Reuben Abel
Language: eng
Format: epub
Publisher: The Free Press
Published: 1976-07-15T00:00:00+00:00

Purposive Adaptation and Functional Explanation

Opponents of this position will point to many striking examples of apparently purposive adaptation: the dolphin is born tail first, since it is an air-breathing mammal, and would otherwise drown. The ostrich has callosities on its undercarriage where it touches the hot desert sand when it sits down. Lemmings can barely survive the rigors of an arctic winter; they therefore multiply with extraordinary rapidity—they can breed at the age of three weeks; their gestation period is twenty days; and there may be as many as thirteen young in a litter. Fireflies have a special rhythmic code whereby some forty different species of males and females can find each other; a certain male, for example, will flash exactly twelve pulses in a third of a second. Some moths have colored spots on their wings that look like eyes (ocelli); this pigmentation confuses predators. In the gypsy moth, the male antenna has some fifty thousand different odor sensors, each one sensitive to one type of molecule; moreover, he can spot his mate a mile away. Survival of a species often depends on remarkable perceptual adaptations: the butterfly selects his mate by responding to an unimaginably minute amount of a chemical; the bee senses ultraviolet rays; some hunting birds have astonishingly sharp sight. Forsythia is yellow; if it weren’t, bees (which are allegedly red-green colorblind) would never find it. Human beings also have various intricate sensory devices: for depth perception; for filtering out stimuli; for perceiving a gestalt out of only a few clues. The human body has a delicate and fragile system of nerves to maintain a steady internal state despite extensive changes in the outside world. Compensatory activities demonstrate “the wisdom of the body”: an over-heated animal drinks to provide sufficient fluid to sweat, and sweating is a means of cooling. Shivering generates heat in the muscles. Goose flesh is an attempt to keep warm by fluffing out what used to be hair.

These frequently hair-raising examples, however, have been adroitly selected, and are ambiguous. The wisdom of the body can be matched by its stupidity: the same compensatory activities also form scar tissue, which produces cirrhosis of the liver as well as asphyxia; the appendix is apparently useless; cancer is the body’s supreme folly. Homo sapiens is one of the few species unable to synthesize within his own body vitamin C (ascorbic acid); it is essential to life. Only man and the other primates are plagued by kidney stones; all other species produce the enzyme uricase, which oxidizes uric acid into a compound that can be dissolved and excreted. The human sinus drains poorly (and gives us trouble) because our four-footed ancestors held their heads down, not up. Child birth is painful and hazardous. Senility is degrading. No intelligent designer of a human body would ever do so poor a job! And, let us place that flashing firefly in appropriate perspective: there is a predatory cannibalistic female firefly that has learned to imitate the mating signals of

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