Steven Vogel is a Professor in the Biology Department at Duke University (N.C., USA). His main research interest is comparative biomechanics. He studies things like the design of fly wings and how organisms adapt to fluids (air and water). His secondary interest is science writing and he has published four books: Life's Devices: The Physical World of Animals and Plants (1988); Cats' Paws and Catapults: Mechanical Worlds of Nature and People (1999); Prime Mover: A Natural History of Muscle (2001); Comparative Biomechanics: Life's Physical World (2003).The excerpt is from Life's Devises. Here, Steven Vogel gives as balanced a description of the use of "design" and "adaptation" as I've seen anywhere.
This book is mainly about organisms, so we will be concerned with a level of biological organization upon which the invisible hand of the selective process should incur fairly immediate consequences. It is the immediacy of operation of that unseen hand that makes organisms appear well designed—as a colleague of mine put it, "The good designs literally eat the bad designs." But it must be emphasized that we mean "design" in a somewhat unusual sense, implying only a functionally competent arrangement of parts resulting from natural selection. In its more common sense, implying anticipation, "design" is a misnomer—it connotes the teleological heresy of goal or purpose. Still, verbal simplicity is obtained by talking teleologically—teeth are for biting and ears for hearing. And the attribution of purpose isn't a bad guide to investigation—biting isn't just an amusing activity incidental to the possession of teeth. If an organism is arranged in a way that seems functionally inappropriate, the most likely explanation (by the test of experience) is that one's view of its functioning is faulty. As the late Frits Went said, "Teleology is a great mistress, but no one you'd like to be seen with in public."
We functional, organismic biologists are sometimes accused of assuming a kind of perfection in the the living world—"adaptationism" has become the pejorative term—largely because we find the presumption of a decent fit between organims and habitat a useful working hypothesis. But the designs of nature are certainly imperfect. At the very least, perfection would require an infinite number of generations in an unchanging world, and a fixed world entails not only a stable physical environment but the preposterous notion that no competing species undergoes evolutionary change. Furthermore, we're dealing with an incremental process of trial and error. In such a scheme, major innovation is not a simple matter—features that will ultimately prove useful are most unlikely to persist through stages in which they are deleterious or neutral. So-called hopeful monsters are not in good odor. Many good designs are simply not available on the evolutionary landscape because they involve unbridgeable functional discontinuities. Instead, obviously jury-rigged arrangements occur because they entail milder transitions. In addition, the constraints on what evolution can come up with must be greater in more multifunctional structures. Finally a fundamentally poorer, but established and thus well-tuned, design, may win in competition with one that is bascially better but still flawed.
I make these points with some sense of urgency since this book is incorrigibly adaptationist in its outlook and teleological in its verbiage. The limitations of this viewpoint will not insistently be repeated, so the requisite grain of salt should be in the mind of the reader as well as the author. Incidentally, the ad hoc character of many features of organisms are recounted with grace and wit in some of the essays of Stephen Jay Gould, not just as an argument against extreme adaptationism but as evidence for the blindly mechanical and thus somewhat blundering process of evolution. His collection entitled The Panda's Thumb (1980) is particularly appropriate here.
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