I'm a big follower of Dawkins, even way before he got famous for this Atheist beliefs. Dawkins is not only a brilliant man, he's a great speaker. I can listen to him talk all day:D
The "selfish gene theory" makes all the sense in the world considering the behavior of almost everything living thing on the planet. Jared Diamond has a great book out there called "Why is Sex Fun? The Evolution of Human Sexuality" that I highly recommend, which supports this theory (though I don't believe he mentions the selfish gene theory specifically).
~Cathy~