Darwin's Dangerous Idea - Evolution and the Meanings of Life by Daniel C. Dennett

Author:Daniel C. Dennett [Dennett, Daniel C.]
Language: eng
Format: epub
Published: 2011-02-05T05:00:00+00:00

268 BULLY FOR BRONTOSAURUS

The Spandrel's Thumb 269

to be a highly successful coinage in one sense: it has spread through evolutionary biology and beyond. In a recent retrospective essay, Gould put it this way:

Ten years later, my friend Dave Raup ... said to me, "We have all been spandrelized." When your example becomes both generic and a different part of speech, you have won. Call those San Marco spandrels "Kleenex,"

"Jell-O," and a most emphatically non-metaphorical "Band-Aid." [Gould 1993a, p. 325.]

Ever since Gould and Lewontin, evolutionists (and many others) have spoken of spandrels, thinking that they knew what they were talking about.

What are spandrels? A good question. Gould wants to convince us that adaptation is not "pervasive," so he needs to have a term for the (presumably many) biological features that are not adaptations. They are to be called

"spandrels." Spandrels are, um, things that aren't adaptations, whatever they are. Gould and Lewontin have shown us, haven't they, that spandrels are ubiquitous in the biosphere? Not so. Once we clear away the confusions about what the term might mean, we will see that either spandrels are not ubiquitous after all, or they are the normal basis for adaptations, and hence no abridgment at all of "pervasive adaptation."

Gould and Lewontin's paper begins with two famous architectural examples, and since a crucial misstep is made at the outset, we must look closely at the text. ( One of the effects of classic texts is that people misremember them, having read them hurriedly once. Even if you are familiar with this oft-

© Alinari/Art Resources, N.Y.

reprinted beginning, I urge you to read it again, slowly, to see how the FIGURE 10.1. One of the spandrels

misstep happens, right before your eyes.)

of San Marco.

The great dome of St Mark's Cathedral in Venice presents in its mosaic mid-line of the vault, where the sides of the fans intersect between the design a detailed iconography expressing the mainstays of Christian faith.

pillars (figure (10.]2). Since the spaces must exist, they are often used for Three circles of figures radiate out from a central image of Christ: angels, ingenious ornamental effect. In King's College Chapel in Cambridge, for disciples, and virtues. Each circle is divided into quadrants, even though example, the spaces contain bosses alternately embellished with the Tudor the dome itself is radially symmetrical in structure. Each quadrant meets rose and portcullis. In a sense, this design represents an 'adaptation', but one of the four spandrels in the arches below the dome. Spandrels—the the architectural constraint is clearly primary. The spaces arise as a nec-tapering triangular spaces formed by the intersection of two rounded essary by-product of fan vaulting; their appropriate use is a secondary arches at right angle (figure [10.]1)—are necessary architectural by-effect. Anyone who tried to argue that the structure exists because the products of mounting a dome on rounded arches. Each spandrel contains alternation of rose and portcullis makes so much sense in a Tudor chapel a design admirably fitted into its tapering space __ The design is so elab would be inviting the same ridicule that Voltaire heaped on Dr Pangloss.

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