[The following is the beginning of a book review that I last edited almost a year ago. It’s obviously never going to be finished (especially as I’ve since loaned the book out), but there are a couple of interesting factoids in there so maybe you’ll get a kick out of it, incomplete though it is.]

I recently [In pre-hiatus time: May 2010 or thereabouts.] finished Genes in Conflict: The biology of selfish genetic elements, by Austin Burt and Robert Trivers (thanks Ralph for the recommendation!). Fascinating, absolutely fascinating.

This is not the simple world of Richard Dawkins’s The Selfish Gene, laid out in thought experiments and catchy slogans. This is a serious textbook for genetic students (I skim-read it with the specifics drifting past my glazed eyes), dense with detailed case studies. It’s also not concerned with Dawkins’s notion of “selfishness” (which applies to all genes) but with a rather more specific one: genes (or other genetic elements: chromosomes, cell lineages, whatever) that achieve reproductive success at the cost of the organism they are a part of.

Take cancer, for instance. Cancer is basically what happens when cell reproduction goes out of control. Looked at a different way, some cell figures out how it can reproduce without being bottled up and shackled down by the constraints that our bodies usually apply to keep everything in order.

Fun (revolting) fact: there exists a cancer that doesn’t just stay in the host that gave rise to it. It’s found only in dogs, around the genitalia, and is passed on by sexual contact. If your pooch catches this cancer, it’s actually playing host to a cell lineage that arose in some other dog entirely. Basically, the cancer is a parasite (that just happens to have originally been part of a dog). Burt and Trivers: “One could even think of it as a highly degenerate mammal.”

Another nice example: imagine a gene living on the Y chromosome (remember from high-school biology that human males –normally– have an X chromosome and a Y, while human females –normally– have two Xs) that makes a man’s sperm produce only sons. It’s not against the man’s direct interests, exactly, but it is certainly against the interests of his species (if it catches on, eventually there won’t be any women any more and humanity will die out). But it will have a short-term advantage, because every one of those sons will carry a copy of it, while any daughters he would otherwise have had would not.

It doesn’t happen with humans, but it does (or something like it) with mosquitos; the reverse pattern (X-linked genes suppressing production of sons) occurs in fruit flies. And something much weirder (a special kind of X chromosome, X*, that suppresses the normal function of the Y, so that X*Y individuals are female) turns up in lemmings.

[And with that fascinating fact, it ends. Interested parties should read the book.]