Behe's irreducible complexity says that the system must have all the
parts in order to function. It also says that there isn't any way for
it to get its parts serially because nothing will function or have any
use until all the parts are there, placed, structurally and functionally
interfaced according to that unique blueprint. Therefore "evolving"
into the structure and function is not possible. It must be
nanoengineered.
I hope this is helpful.
Joseph Mastropaolo