It has been well established that evolution does occur in the sense that random variations do occur in living organisms. Imagine a radio signal is being broadcast and the signal is being corruped by static or noise as it’s properly called. Noise has the effect of destroying information. So for example a crackle on the radio would cause words to become garbled. In genetic terms this could result in a poor immunity system for example. However in rare cases noise could accidentally corrupt a signal corrupted signal resulting in an actual improvement in the message being transmitted. However this would be exceptionally rare. Random variations are almost always damaging.
The finch beak if probably the best known example. Darwin observed variations in the length and shape of finch beaks and sometimes these variations were actually useful for the survival of the finch. This is an example of micro or horizontal evolution i.e evolution which produces a chance in existing function but does not create new function.
Creating new function however is whole different ball game because it requires the creation of new information. You can’t build something unless you have plans (DNA) to build it. Therefore macro or vertical evolution cannot be explained by neo-darwinism which is natural selection operating on random processes. This theory is borne out by what is known as the Cambrian Explosion. According to the fossil records, there was a sudden change found in the rock strata in terms of abundance and diversity of animal life.
The problem is that evolution cannot account for this rapid change because evolution is an extremely slow process. The other problem for evolution is that the fossil records shows sudden and discrete jumps in skeletal form instead of the very smooth transition you would expect to find according to evolution. Why the significant gaps in the fossil record?
(TODO - some notes about how all parts of the mechanism need to be in place for the whole mechanism to function)