Imagine that you purchase a “build it yourself” computer kit, and all the instruction manual said is “Step 1: Collect all necessary parts into a box.” This is essentially as far as evolutionary explanations by co-option get: Darwinists assume that by simply identifying the possible origin-location for one or a few structural components that they have explained how all of the parts became properly assembled to interact and produce the final functional structure.
Mike Gene has a funny post where he links to computer assembly instructions which simply tell the user to tape the necessary computer parts inside a box. “Exiled from Groggs” thinks that this shows “The limitations of co-option.” It appears that scientists would agree. As one scientist explained in the journal Science when discussing systems biology: “Identifying all the genes and proteins in an organism is like listing all the parts in an airplane. While such a list provides a catalog of the individual components, by itself it is not sufficient to understand the complexity underlying the engineered object. We need to know how these parts are assembled to form the structure of the airplane.” (Hiroaki Kitano, “Systems Biology: A Brief Overview,” Science, Vol. 295:1662-64 (March 1, 2002).)
This comment was made in the context of discussing systems biology, but perhaps someday, when it is no longer politically deadly to question Darwin, science journals will regularly explicitly discuss the bankruptcy of evolutionary explanations via co-option.