Irreducible Complexity

Here, I want to draw attention to a review article by Levine and Holland, published in 2018, on “the impact of mitotic errors on cell proliferation and tumorigenesis.” Noting that “mitosis is a delicate event that must be executed with high fidelity to ensure genomic stability,” the paper underscores the critical nature of various aspects of the eukaryotic cell cycle machinery.

The process of chromosomal condensation is absolutely essential to successful mitotic cell division — that is to say, it is a part of a larger irreducibly complex system. Moreover, the highly condensed mitotic chromosome structures (with sister chromatids joined at the centromere) do not serve a purpose apart from in the context of mitosis. And yet, various components are themselves indispensable for effective chromosome condensation.

What makes the origins of the eukaryotic cell cycle particularly resistant to evolutionary explanations is that a wide gulf exists between the mechanism of cell division by eukaryotes and that employed by prokaryotic cells — both in terms of the protein components involved, as well as the underlying logic. There is essentially nothing in common between the two systems.

Various components of the mitotic cell division apparatus are indispensable for the system to work. This makes the eukaryotic cell division irreducibly complex, rendering it resistant to explanations in terms of blind, evolutionary processes.

My new paper is out now in the journal BIO-Complexity, regarding the origins of the eukaryotic cell division cycle.

Have you ever wondered how our fingers and toes form during embryonic development? Our digits are, in fact, sculpted from a paddle-like structure in the embryo through the process of apoptosis — that is, programmed cell death. During early development, the hands and feet begin as solid, webbed structures. Through carefully controlled apoptosis, the tissue between them is eliminated, facilitating the separation of the digits.

The spindle assembly checkpoint pathway is an elegantly engineered surveillance system for protecting the cell from the adverse consequences of improper kinetochore-microtubule attachment.

In a recent article, I discussed the astounding role of motor proteins in eukaryotic cell division. But this is just one of many incredible engineered features associated with mitosis. In this and a subsequent article, I will provide an overview of the elegant molecular mechanisms that underlie the spindle assembly checkpoint and discuss the implications of its dysfunction.

These molecular motors are absolutely indispensable to successful cell division in eukaryotes and thus constitute an irreducibly complex system. It therefore points forcefully and unequivocally to conscious intent.

Last week, I wrote an article highlighting the irreducible complexity of the DNA replisome. A reader asked me whether the complexity of the DNA replisome could in fact be used as an argument against intelligent design.