An interesting paper out of Cornell University explores the origin of the human genome pre-Earth. Alexei Sharov and Richard Gordon explore genetic creation for the last nearly 10 billion years.
It is an interesting paper, mathematically and as to what is truly alien
The link to the blog entry / abstract is here and on that page are links to all the pertinent info and supporting materials.
The abstract is very clearly written and even the paper itself seems accessible to most anyone with an interest in mathematics, genetics or both.