Expert: Dana Krempels, Ph.D. - 11/2/2007

Question
I have heard information about a flagellum that I need to confirm with the experts. I do not know enough, so I am consulting you. I have heard that questions have been raised about how flagella have developed. Some say that the "motor" system of the flagellum is "irreducibly complex", and that all parts are interdependent, meaning that if any parts are not present, the system does not work at all. The question is: How could the system have been developed according to Evolution if the motor system on the flagellum would not work without all of it's present parts? Do the cilia and the flagella work differently? What is your theory as to how this system developed?

Answer
Dear Alexander,

A cilium is basically a short flagellum, and they operate in very much the same way.  The argument about the motor system of these structures being "irreducibly complex" is often used by those who insist that the living world is a product of "Intelligent Design," and the problem is that they assume that the structures they mention were always used for the purpose to which they are put today.  This is simply not the case.

For an excellent overview of the problems with the "irreducibly complex" argument for ID, please read:

http://www.actionbioscience.org/evolution/nhmag.html

I think it will make things very clear.  :)

I hope that helps!
Dana