I read the 1989 edition of The Selfish Gene, not the 2006 edition, because I bought it in 2001 and hadn't gotten around to reading it yet. This edition includes the original 11 chapters plus two added on in 1989 as an update. It's a nice idea to include an update, but in 1989 we used 5 1/4" diskettes to start up our Apple IIe computers, and molecular genetics was in a similar stage. The 2006 edition adds only an introduction.
It's a moot argument
The Selfish Gene is poised as a modern progression from The Origin of Species, in which Darwin proposes that all living species evolved from a common ancestor, and that evolution was driven by natural selection. In The Selfish Gene, Dawkins proposes that the fundamental unit on which natural selection acts is the gene, not the organism or the species. He points out a counterargument to this theory, that it does not account for altruism among individuals or among genes, and he spends most of the book explaining the genetic advantage of altruism.
Honestly, I don't care too much about this argument. Natural selection depends on differences, and if two items (genes, individuals, or populations) are identical, natural selection isn't effective. If they are different enough that one has a reproductive advantage, and they must compete, it will work. As several chapters contest, altruism and group interactions benefit all of those involved. I don't need a book to explain that to me.
The language of behavioral genetics
And yet I had considerable trouble agreeing with this book. I think it's in the way the evidence was presented. In the 1970's at least, Dawkins was a naturalist. (Now he might be better described as a militant atheist.) Like Darwin, he studied animals and how they interact with each other and their environments. His evidence is anecdotal, examples of how birds or insects behave, and he takes an enormous leap from that behavior to genetics by supposing a gene for a particular behavior. Then in the last chapter (after supposing a gene for the stones chosen by a caddis insect in building its house) he writes:
If it is legitimate to speak of a gene as affecting the wrinkliness of a pea or the nervous system of an animal (all geneticists think it is) then it must also be legitimate to speak of a gene as affecting the hardness of the stones in a caddis house.
No! Wrong! Gregor Mendel showed with experimental evidence that one gene is responsible for the wrinkly or smooth coat of a pea! I don't know if anyone has identified that gene and the protein it encodes, but if they did, they might find it is a cell surface protein that controls the intake of water into the pea (more water makes it fuller, and smooth). Until someone shows me the gene for caddis stone hardness, defines the cellular function of the protein it encodes, and identifies a mutation that alters stone hardness, I don't agree that this language is legitimate, and don't make assumptions about what "all geneticists think."
The 1976 edition ended with a chapter introducing the concept of memes, which we all now know as self-replicating ideas. He gives an interesting example, that Darwin's theory of evolution by means of natural selection is a meme. As this theory was passed from Darwin's brain to others, and from those to others still, it evolved. The BBC miniseries Darwin's Dangerous Idea explains many of the ways his meme evolved for nefarious purposes (for example, to justify ethnic cleansing or social Darwinism).
I've decided that The Selfish Gene is no longer relevant. Its main thesis is moot, and memes have penetrated even popular culture. Presumably Dawkins' more recent books update these ideas, but his writing style doesn't make me want to read any more. He's cocky and self-assured, and he's enamored with footnotes. It's as if I walked into the middle of a debate, and Dawkins is arguing all sides at the same time. The abundance of commentary, coupled with the anecdotal naturalist stories, invited me to skim rather than savor. I was constantly wishing he'd get to the point.