Thanks. Aren't most adaptions beneficial to the survivial of the species? What drives them to adapt? A chemical process I guess - but why? And why do some species end up extinct? I'm sure this argument could go on and on but I guess I'm looking for the short version answer. Thanks again.
The Theory of Evolution. Excellent introductory encyclopedia article.
The Pocket Darwin. Very good, easily readable summary.
It's essentially all passive. Entities (animals, plants, bacteria, etc.) have offspring that are slightly different from themselves.
Those that are adequate (fit, lucky, whatever it takes) survive to have offspring of their own. The next generation is slightly different again.
Inexact replication then selection.
Not all mutations are beneficial, but an adaptation pretty much by definition would always be beneficial in the short term. Even then, there's such a thing as an evolutionary blind alley.