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Cell Biology

Irreducible Complexity

When a number of component parts of a machine have to be present and to interact precisely in order for the machine to work, the machine is said to be irreducibly complex. That means that if you take away even one component part, the machine does not work.

This is significant for origins theories because if all of the parts have to be present for the system to work, then an evolutionary process of gradual change could not produce a working system. A partial, non-functioning system would not provide anything for natural selection to work on, so evolutionary explanations cannot explain the living cell and origin of life theories, for example.

The most famous example of irreducible complexity is the bacterial flagellum. A recent series of articles on this topic appeared. See Waldean A. Schulz. 2021. An Engineering Perspective on the Bacterial Flagellum. Part I Constructive View; Part 2 Analytic View; Part 3 Observations: Bio-Complexity

These articles look in detail at the purpose of the bacterial motility system, the more than 40 protein components and how they are assembled, and observations of specific protein-binding relationships. From all this, the following conclusions have been drawn: “The above facts about the intricacy of the structure, control, function and assembly of the flagellum are objective. Engineers, and patent offices always attribute functional devices – even trivial ones – to some intelligent designer(s), implementor(s), or inventor(s). Meanwhile, the evolutionary biological community has yet to hypothesize a likely, detailed, step-by-step scenario to explain how the flagellum and its control system could have been blindly engineered naturalistically.” [2 – p. 15 italics his]

“The flagellum seemingly is irreducible. How would portions of an incomplete, nascent flagellum be protected from degradation for generations while the remainder was yet to be gradually added?”  [ 2- p. 15]

“The overwhelming observation from this flagellum study, noted in the section on exquisite bindings, is that each of the structural proteins of each of the flagellum’s subassemblies require an extremely precise molecular configuration in order to simultaneously comply with several very specific required properties.” [3 – p. 6]

“Attributing the implementation of a bacterial flagellum to neo-Darwinian evolution, where no substantive evidence for such a construction exists, seems like presumptive faith in the magic of very fortuitous co-option and the step-wise mutations of duplicated genes, intercellular gene transfer, exaptations, and de novo saltations [jumps]. It involves a philosophical prior commitment to Naturalism.” [3 – p. 6]

“A motility organelle of this scope and scale seems profoundly unlikely to naturally evolve in the absence of foresight and mindful intent.”  [3 – p. 7]

So, many aspects in the cell and biology in general are irreducibly complex. The examples are endless. One just has to keep one’s eyes open.

Related Resources

Related Terms

  • Co-option
  • Flagellum
  • Molecular Machines
  • Natural Selection
  • Functionality