Today is Ask An Atheist Day.

[LostOne4Ever]

52. Been a long time since i took evolutionary biology

Been a long time since i took evolutionary biology, comparative vertebrate anatomy, etc. but i will try and answer that. But keep in mind I could have some major mistakes because, again, its been years since I took those classes.

The lung came first. It developed in bony fish as the swim bladder. Its purpose was to keep fish afloat even when they were sleeping. Sharks and other non-bony fish lack this organ. How did these organs come about? Through mutation. Must mutations are fatal to the organism but sometimes they can provide a benefit. When this benefit gives the organism an adaptive advantage that organism is more likely to reproduce and pass on the gene. If the gene provides a big enough advantage those genes will spread through out the population.

This is the definition of evolution. Genetic change in a POPULATION (keyword here) over time.

Some times these genes are so advantageous that the trait takes over or the organisms will seek OUT mates with these traits which causes them to become exaggerated over time (think of selective breeding by animal breeders). If the animal with the longer neck can reach food higher up on the trees keeping them from starving to death that trait will give them an advantage and become predominate over time. Slowly these changes add up until the animal becomes a different species or develop unique traits like wings, lungs, feet, etc. There is no thought to it. I hope this answered your question and I hope i did not mess up =P

As for too perfect to be random or coincidence, that is actually wrong. In true chaos small sections of order will arise on their own. A good way to tell if something is truly random is too look for repeats.