Originally Posted by Crowbar
Thus, even a bacteria already contains in it complexity that is of the same order of magnitude as a human.
Hmm... are you sure of that? You seem to set an amoeba at the same level of complexity of a human stem cell, or a fertilized human egg. Are you sure someone has compared those complexity levels appropriately? Or rather, are you sure that
you are comparing them appropriately? Such comparison might trascend biology, might involve complexity theory and math.
A fertilized human egg, regardless of how many genes shares with an amoeba, has other extremely complex internal encodings in its DNA to allow for the appearance of very different types of cells, which can eventually form organized and highly differentiated, yet cooperating tissues, so that they work together allowing the existence of a very complex multicellular organism. These internal encodings allowing the proper morphology of that organism (from just one cell!) involve such complex things as multiplication of specific cell types
up to a specific population size, precise orientation/placement of such cell types with respect to some other surrounding cell types, and might involve even programmed self-destruction of specific cells at specific points in time during the early development stages of that organism. All of this extra "programming complexity" guiding the coordination and progressive arrangement and workings of millions of cells of different types (all in just one cell at the beginning, or we should really say just two: fertilized egg + fertilizing spermatozoid) is clearly beyond what the typical unicellular organism has genetic information for. In what magnitude it is "beyond", well that I'm not sure, but that's part of my point.
Percentage of genes shared is not the same as the operational complexity of different genetic machineries. I don't think it is that easy to compare the complexity levels of the way different genetic codes work, despite the fact that they are based on the same molecules and might share large %s of genes. Moreover, in multicellular organisms there are extra complexities associated to ongoing interactions and interregulations between tissues; extra operational complexities that pile up on top of the extra genetic and morphological level complexities.
Now, there's also the point that operational complexity of a genetic code may not necessarily be the best measure of evolutionary advancement. Depends on how biologists choose to define evolutionary advancement or "success".