Realistic Cooption.

It seems clear to me that, at the very least, Behe’s book “Darwin’s black box” stimulated interest in, thinking about and probably research into - the origin of complex integrated biological systems.

As I understand it the current Miller/Matzke etal explanation for the origin of the rotary motor propulsion systems in bacteria is a series of cooption events.


Function 1 (1 or more proteins)

↓

← Function 2 (1 or more proteins)
↓

Function 3 (2 or more proteins)

There is an assumption that all the proteins which form the motor have all been collected and modified from other purposes in the bacterial cell. In the words of the New Scientist article- it was “cobbled together.” Some of the proteins in the motor have not been found to have any homologues elsewhere but let us assume that homologies for all the proteins will be found at some point.

My big question is whether this explanation is realistic. Obviously we can imagine it happening providing if we try hard enough. The big question that remains to me is whether this is just wishful thinking. Is it realistic to imagine this happening? How can we know when a series of imagined cooption events is realistic or not.

Obviously if we find compelling examples of intermediate stages this helps but is there a way in which we can test whether our evolutionary imaginations are being kept within realistic limits?