That was just one, easy to understand example that anybody could understand.  Over long periods of time, these mutations and natural selection add up and change the organism to the point where its not the same organism that it was 20,000 years ago.

How do you account for the fossil record and atomic decay without evolution?  Do you think God destroys Earth every 20,000 years and creates new species that resemble the ones before?

First of all, carbon dating is only accurate to what, 10,000 years? Other forms of dating assume the amount of starting nuclear material can be calculated by extrapolation, which may or may not work.

Secondly, I personally think evolution could work, I just find it unlikely, and it still fails to explain the origin of life, all there really is, is the miller experiment, which frankly is a joke, as apparently the early atmosphere was different to the experiment, so it doesn't really have much relevance any more!

Carbon dating is accurate for 50,000 years.  Evidence for the accuracy of other decay rates is solid too.  Thats not to mention other geological methods, for instance the sea floor spreads at 3 cm a year, so we can assume this rate would be similar over time and say that North America and Africa were joined 100 million years ago.  Even if the assumption is wrong (unlikely) the two contininents would have been joined on the scale of millions of years ago in the least.

Evolution does work, our understanding of biology and genetics has proven beyond a doubt to everyone except the most stubborn of people (religious literal creationists who fear evolution hurts their religion).  The origin of life itself is tricky, buts not far a stretch to say that chemical compounds reacting in primitive Earth is a better idea than a super being who keeps getting his timeline pushed back.  One a chemical compound forms that is able to replicate itself, the path to complex life has been set.  Thats not to mention that a single cell isn't even a single living thing (technically speaking), ancient cells actually took in mitochondria from their environment and they ended up working for the benefit of the cell.  Mitochondria even have their own RNA.