Just to confuse everything once you have got a handle on selfish genes, you could glance at Stephen Gould's tome 'The Structure of Evolutionary Theory'. Gould suggested that selection works at all three levels - gene, individual and species. Makes sense to me!
Thesis, antithesis, synthesis, I guess.
NB. I don't recommend actually READING the book - one doesn't live that long. I read about a quarter, then skipped through the rest.
Mike.