Irreducible Complexity—Evolution’s Stumbling Block?

When Darwin developed his theory, scientists had little or no knowledge of the amazing complexity of the living cell. Modern biochemistry, the study of life at the molecular level, has revealed some of that intricacy. It has also raised serious questions and doubts about Darwin’s theory.

The components of cells are made up of molecules. Cells are the building blocks of all living creatures. Professor Behe is Roman Catholic and believes in evolution to explain the later development of animals. However, he raises serious doubts about whether evolution can explain the existence of the cell. He speaks of molecular machines that “haul cargo from one place in the cell to another along ‘highways’ made of other molecules . . . Cells swim using machines, copy themselves with machinery, ingest food with machinery. In short, highly sophisticated molecular machines control every cellular process. Thus the details of life are finely calibrated, and the machinery of life enormously complex.”

Now, all of this activity is taking place on what scale? A typical cell is only one thousandth of an inch [0.03 mm] across! In that infinitesimal space, complex functions vital to life are occurring. (See diagram, pages 8-9.) Little wonder that it has been said: “The bottom line is that the cell—the very basis of life—is staggeringly complex.”

Behe argues that the cell can function only as a complete entity. Thus, it cannot be viable while being formed by slow, gradual changes induced by evolution. He uses the example of a mousetrap. This simple apparatus can function only when all its components are assembled. Each component on its own—platform, spring, holding bar, trap hammer, catch—is not a mousetrap and cannot function as such. All the parts are needed simultaneously and have to be assembled for there to be a working trap. Likewise, a cell can function as such only when all its components are assembled. He uses this illustration to explain what he terms “irreducible complexity.”b

This presents a major problem for the alleged process of evolution, which involves the appearance of gradually acquired, useful characteristics. Darwin knew that his theory of gradual evolution by natural selection faced a big challenge when he said: “If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.”—Origin of Species.

The irreducibly complex cell is a major stumbling block to belief in Darwin’s theory. In the first place, evolution cannot explain the leap from inanimate to animate matter. Then comes the problem of the first complex cell, which must arise in one fell swoop as an integrated unit. In other words, the cell (or, the mousetrap) must appear out of nowhere, assembled and functioning!

The Irreducible Complexity of Blood Clotting

Another example of irreducible complexity is a process most of us take for granted when we cut ourselves—blood clotting. Normally, any liquid will immediately leak out of a punctured container and will do so until the container is empty. Yet, when we puncture or cut our skin, the leak is quickly sealed by the formation of a clot. However, as doctors know, “blood clotting is a very complex, intricately woven system consisting of a score of interdependent protein parts.” These activate what is called a clotting cascade. This delicate healing process “depends critically on the timing and speed at which the different reactions occur.” Otherwise, a person could have all of his blood clotting and solidifying, or on the other hand, he could bleed to death. Timing and speed are the vital keys.

Biochemical investigation has shown that blood clotting involves many factors, none of which can be missing for the process to succeed. Behe asks: “Once clotting has begun, what stops it from continuing until all the blood . . . has solidified?” He explains that “the formation, limitation, strengthening, and removal of a blood clot” make up an integrated biological system. If any part fails, then the system fails.

Russell Doolittle, evolutionist and professor of biochemistry at the University of California, asks: “How in the world did this complex and delicately balanced process evolve? . . . The paradox was, if each protein depended on activation by another, how could the system ever have arisen? Of what use would any part of the scheme be without the whole ensemble?” Using evolutionary arguments, Doolittle tries to explain the origin of the process. However, Professor Behe points out that there would be an “enormous amount of luck needed to get the right gene pieces in the right places.” He shows that Doolittle’s explanation and casual language conceal tremendous difficulties.

Thus, one of the major objections to the evolutionary model is the insurmountable hurdle of irreducible complexity. Behe states: “I emphasize that natural selection, the engine of Darwinian evolution, only works if there is something to select—something that is useful right now, not in the future.”