While computer hardware approaches the complexity of a human brain (the latest supercomputer is capable of 200,000,000,000,000 op/s), the software is lagging behind miserably. We have recursive algorithms, neural nets, genetic programming, swarm intelligence and so on, but the AI field is unable to produce a program as complex as a fly. Let's compare simple one-cell organisms, such as amoebas, to modern computer viruses and worms. Do you see any similarities? It was amoeba that had gradually evolved into multicell clusters, which in turn gave birth to the simplest worms and insects. I see operating systems and internet as a perfect enviroment for similar evolution. Antivirus programs provide the necessary natural selection, so an effective virus must make more and more decisions to survive on your machine and to replicate itself.
Who knows, maybe the next civilization on this planet will have its roots in modern trojans, spiders, RAT botnets, spamware and viruses.