I just finished reading the Selfish Gene by Richard Dawkins.
This book makes for really interesting reading, if you are interested in evolution. Certainly, I now have a much better understanding of how natural selection works, but by far the most impactful element of the book is how it changes the way you view life in general. Dawkins proposes a view of life that is fascinating and irresistible. This view is that to better understand why we are here and even how we are here, we should focus on the viewpoint of the genes. Genes were here first, and in general we can refer to them as replicators, the things that actually copy themselves, and thus live on through geological time. Our bodies, us as entities, as creatures, are simply robots, or survival machines that the replicators use to give them the best chance for survival in their timescale. Our bodies are honed, via the process of natural selection acting on the various variations and mutations of behaviour that the genes produce.
In the process of human evolution, we have developed fantasticly complex brains capable of great self awareness and intelligence. Obviously the mutations and variations that led us down this path has been a great success story for our genes, for they now dominate the planet through us. However, this intelligence and self awareness gives us the ability to ignore many of the behaviours produced by our genes, thus taking control slowly away from them. Dakwins discusses his meme theory of evolution of cultural behaviour as part of this, separate but analagous to genetic evolution.
Everyone should read this book.