Intelligent Design.....part two
Intelligent design versus emergent complexity. The theory of intelligent design, or ID, is a theory of sequential origins, but it is also the latest attack on the idea that the origin and evolution of life follow natural laws. Like created antiquity, ID has a long intellectual pedigree. The English philosopher William Paley first espoused it in 1802, arguing that if you found a watch in a field, you would conclude that it had been designed by some intelligence rather than assembled by chance. In the same way, the argument goes, the intricate universe in which we live reflects the mind of an intelligent maker.
The modern theory of intelligent design is more sophisticated than Paley's argument, although it derives from much the same kind of reasoning. It is anchored in a concept called "irreducible complexity" - the idea that organisms possess many complicated structures, which are essential to the organism's survival but which are useless unless all the structures are present. The chance of Darwinian evolution's producing so many such structures and of their existing simultaneously, according to the theory, is so small that they must have been produced by an intelligent designer.
Intelligent design challenges the conventional wisdom in origin-of-life research that life is a prime example of so-called emergent complexity. All around us are complex systems that arise when energy flows through a collection of particles, like living cells or grains of sand. Ant colonies, slime molds, sand dunes, spiral galaxies, traffic jams, and human consciousness are examples of such systems. Although scientists have yet to produce a living system in the laboratory, most origin-of-life researchers are optimistic that one day we will be able to do so, or at least to understand how life first emerged from inorganic materials.
The supporters of intelligent design resort to the same kind of argument that creationists have used for decades, identifying some biological structure and claiming that it is irreducibly complex. Then supporters of emergent complexity have to analyze that structure and show that its complexity arises naturally. For example, 20 years ago, the predecessors of ID advocates pointed to the modern whale as an example of what would be called irreducible complexity today (that term wasn't used then). The whale, they argued, is a form so specialized that it could not possibly have been produced by Darwinian evolution.
Alan Haywood, author of Creation and Evolution, put it this way: "Darwinists rarely mention the whale because it presents them with one of their most insoluble problems. They believe that somehow a whale must have evolved from an ordinary land-dwelling animal, which took to the sea and lost its legs. ... A land mammal that was in the process of becoming a whale would fall between two stools - it would not be fitted for life on land or at sea, and would have no hope for survival."
The power of science is that, faced with such a challenge, one can test the relevant theory. The theory of evolution predicts that whales with atrophied hind legs must have once swum in the seas. If Darwin is correct, then those whales' fossils must lie buried somewhere. Furthermore, those strange creatures must have arisen during a relatively narrow interval of geological time, after the evolution of the earliest known marine mammals (about 60 million years ago) and before the appearance of the streamlined whales of the present era (which show up in the fossil record during the past 30 million years). Armed with those conclusions, paleontologists searched shallow marine formations from 35 million to 55 million years in age. Sure enough, in the past decade the scientists have excavated dozens of those "missing links" in the development of the whale - curious creatures that sport combinations of anatomical features characteristic of land and sea mammals.
But there's always another challenge to evolution, always another supposed example of irreducible complexity. At the present time the poster child of intelligent design is the flagellum of a bacterium. That complex structure in bacterial walls features a corkscrew-shaped fiber that rotates, propelling the bacterium through the water. Obviously, a completely functioning flagellum is very useful, but it is also obvious that all its parts have to be present for it to function. A nonmoving corkscrew, for example, would be useless and would confer no evolutionary advantage on its own. Roughly 50 molecules are involved in constructing the flagellum, so the probability of all the parts' coming together by chance seems infinitesimally small.
However, that intelligent-design argument contains a hidden assumption: that all parts of a complex structure must have had the same function throughout the history of the development of the organism. In fact, it is quite common for structures to have one function at one time and be adapted for quite another use later on. A land animal's legs become a whale's flippers. An insect may develop bumps on the side of its body to help it get rid of internal heat, but when the bumps get big enough, they may help the insect glide or fly, thus opening up an entirely new ecological niche for exploitation. That process is so common that evolutionary scientists have given it a name: exaptation.
No evolutionary theorist would suggest that something as complex as the flagellum appeared ab initio. Instead, it was assembled from parts that had developed for other uses. For example, some molecules produce energy by rotating, a normal procedure within cells. Other molecules have a shape that makes them ideal for moving materials across cell membranes. The flagellum's building blocks include both types of molecules. Instead of being assembled from scratch, then, the flagellum is put together from a stock of already existing parts, each of which evolved to carry out a completely different task. The flagellum may be complicated, but it is not irreducibly complex.
An important distinction between the theories of intelligent design and miraculous creation is that the former makes predictions that can be tested. The problem with ID, at least so far, is that when statements like the one claiming irreducible complexity for the flagellum are put to the test, they turn out to be wrong.
That distinction means that we should use different methods to counter intelligent design than those that defeated young Earth creationism. The more thoughtful advocates of intelligent design accept many of the tenets of Darwinism - the idea that living things have changed over time, for example. Although the motive of some ID proponents may be to re-introduce God into the debate about the origin of life, their arguments can be met with scientific, not legal, rebuttals. That is good news: They are playing on our field.