The key for Darwinian evolution is the increase in information and the transmission of such. For example, the information needed for slime to produce more slime only needs to be sufficiently slimy, but the information needed to transition to a sophisticate is indeed astronomic.
“That is, particles-to-people evolution requires changes that increase genetic information (e.g., specifications for manufacturing nerves, muscle, bone, etc.), but all we observe is sorting and, overwhelmingly, loss of information. We are hardpressed to find examples of even ‘micro’ increases in information, although such changes should be frequent if evolution were true. Conversely, we do observe quite ‘macro’ changes that involve no new information, e.g. when a control gene is switched on or off. Interestingly, even high profile evolutionists (e.g. Mayr, Ayala) disagree with the idea that the observed small changes in living things are sufficient to account for the grand scheme of microbes-to-mankind evolution.” ((From http://creation.com/qa#bad_arguments))