I wasn’t disappointed. The book is a rattling good read, and I highly recommend it. Unlike Seven Daughters, this one is not primarily concerned with the reconstruction of phylogeny, so it is not a Y-chromosome counterpart to Sykes’s MtDNA studies. It has more in common with Steve Jones’s Y: the Descent of Man, but there is little overlap in detail, and overall I prefer Sykes’s book. Highlights include a fascinating history of human chromosome studies, a clear explanation of sex determination mechanisms, and a racy account of the ancestry of the Clan Donald.
But the main theme of the book is the conflict between different parts of the genome: mitochondria, Y-chromosomes, and other nuclear genes, all having different interests. Sykes argues persuasively that mitochondria or Y-chromosomes have succeeded in biasing some human lineages towards producing girls and boys respectively. He also argues that the interest of the nuclear genes in avoiding conflict between different strains of mitochondria is the main reason for the differentiation of two sexes in the first place. I’m not so convinced by this, but it’s an interesting theory.
Where I really part company with Sykes is over the deterioration of the Y-chromosome. As I pointed out in my comments on Jones, there are good reasons for the Y-chromosome to deteriorate, but this need not cause any great harm. Sykes takes a different view: it will be ‘death by a thousand cuts. Unable to repair themselves by recombination, the wounded Y-chromosomes will stagger on through succeeding generations, gradually becoming weaker and weaker… As human Y-chromosomes in general become more and more unhealthy there will be a relentless and progressive reduction in male fertility…’ Eventually, the only hope for the human race will be to replace the traditional method of reproduction by artificial insertion of genes into the egg – perhaps female genes! Hence the gloomy prediction of the book’s title. Sykes even estimates the time it will take for men as we know them to become extinct, concluding that it is about 5000 generations or 125,000 years.
It is an ingenious and alarming (or exciting, for lezzers) theory, but, as Captain Blackadder would say, it has one tiny flaw: it is bollocks.
The objections are both theoretical and empirical….