Every student of biological evolution learns about peppered moths. Here we have the same issue and cause. The dramatic increase in dark forms of this species during the industrial revolution, and experiments pointing to differential bird predation as the cause, have become the classical story of evolution by natural selection. The same careful scientific approach which established the classical story in the first place, however, has now revealed major flaws in it. It is time to take another look.

The peppered moth, Biston betularia, comes in various shades of gray. One hundred and fifty years ago, the species consisted almost entirely of "typical" forms, with predominantly light gray scales interspersed with black (hence the name, "peppered"). In 1848, a coal-black "melanic" form was collected near Manchester, England, and by 1950 melanic forms made up more than 90% of the peppered moths in that area. A similar change was reported in many other species of moths, as well as in ladybird beetles, spiders, and even some birds. Since the phenomenon was observed not only around Manchester but also near other industrial centers such as Birmingham and Liverpool, it became known as "industrial melanism."

Irreducible Complexity: The Challenge to the Darwinian Evolutionary Explanations of many Biochemical Structures

With this statement, Charles Darwin provided a criterion by which his theory of evolution could be falsified. The logic was simple: since evolution is a gradual process in which slight modifications produce advantages for survival, it cannot produce complex structures in a short amount of time. It's a step-by-step process which may gradually build up and modify complex structures, but it cannot produce them suddenly.

Darwin, meet Michael Behe, biochemical researcher and professor at Lehigh University in Pennsylvania. Michale Behe claims to have shown exactly what Darwin claimed would destroy the theory of evolution, through a concept he calls "irreducible complexity." In simple terms, this idea applies to any system of interacting parts in which the removal of any one part destroys the function of the entire system. An irreducibly complex system, then, requires each and every component to be in place before it will function.

As a simple example of irreducible complexity, Behe presents the humble mousetrap.

It contains five interdependent parts which allow it to catch mice: the wooden platform, the spring, the hammer (the bar which crushes the mouse against the wooden base), the holding bar, and a catch. Each of these components is absolutely essential for the function of the mousetrap. For instance, if you remove the catch, you cannot set the trap and it will never catch mice, no matter how long they may dance over the contraption. Remove the spring, and the hammer will flop uselessly back and forth-certainly not much of a threat to the little rodents. Of course, removal of the holding bar will ensure that the trap never catches anything because there will again be no way to arm the system.

Now, note what this implies: an irreducibly complex system cannot come about in a gradual manner. One cannot begin with a wooden platform and catch a few mice, then add a spring, catching a few more mice than before, etc. No, all the components must be in place before it functions at all. A step-by-step approach to constructing such a system will result in a useless system until all the components have been added. The system requires all the components to be added at the same time, in the right configuration, before it works at all.

How does irreducible complexity apply to biology? Behe notes that early this century, before biologists really understood the cell, they had a very simplistic model of its inner workings. Without the electron microscopes and other advanced techniques that now allow scientists to peer into the inner workings of the cell, it was assumed that the cells was a fairly simple blob of protoplasm. The living cell was a "black box"-something that could be observed to perform various functions while its inner workings were unknown and mysterious. Therefore, it was easy, and justifiable, to assume that the cell was a simple collection of molecules. But not anymore. Technological advances have provided detailed information about the inner workings of the cell. Michael Denton, in his book Evolution: A Theory in Crisis, states "Although the tiniest bacterial cells are incredibly small, weighing less than 10^-12 grams, each is in effect a veritable microminiaturized factory containing thousands of exquisitely designed pieces of intricate molecular machinery, made up altogether of one hundred thousand million atoms, far more complicated than any machine built by man and absolutely without parallel in the non-living world." In a word, the cell is complicated. Very complicated.

In fact, Michael Behe asserts that the complicated biological structures in a cell exhibit the exact same irreducible complexity that we saw in the mousetrap example. In other words, they are all-or-nothing: either everything is there and it works, or something is missing and it doesn't work. As we saw before, such a system cannot be constructed in a gradual manner-it simply won't work until all the components are present, and Darwinism has no mechanism for adding all the components at once. Remember, Darwin's mechanism is one of gradual mutations leading to improved fitness and survival. A less-than-complete system of this nature simply will not function, and it certainly won't help the organism to survive. Indeed, having a half-formed and hence non-functional system would actually hinder survival and would be selected against. But Behe is not the only scientist to recognize irreducible complexity in nature. In 1986, Michael J. Katz, in his Templets and the explanation of complex patterns (Cambridge: Cambridge University Press, 1986) writes:

Katz continues that this sort of complexity is found in biology:

"Cells and organisms are quite complex by all pattern criteria. They are built of heterogeneous elements arranged in heterogeneous configurations, and they do not self-assemble. One cannot stir together the parts of a cell or of an organism and spontaneously assemble a neuron or a walrus: to create a cell or an organisms one needs a preexisting cell or a preexisting organism, with its attendant complex templets. A fundamental characteristic of the biological realm is that organisms are complex patterns, and, for its creation, life requires extensive, and essentially maximal, templets."