Top positive review
39 people found this helpful
The genetics of real people
on 24 June 2004
According to Bryan Sykes, a 300 million year long experiment is about to conclude. The experiment is mammalian sex. The investigation into how best to reproduce and extend the species is running out of material - the Y chromosome. In a beautifully written, if somewhat suspect, work, Sykes surveys how sex became the driving force of evolution and what that means for humanity today - and tomorrow.
He describes the years of research, including many false starts, leading to the identity of the chromosomes determining our gender. Knowledge of the chromosomes came soon after Darwin's revelation of evolution by natural selection. Darwin realized that sex played a fundamental role in the mechanism of evolution, but the details remained an enigma. Unaware of genes, he still managed to envision the role of sexual selection among animals. When the process of cell division was understood, it led to searching for the means by which traits were transmitted through generations. "Dark blobs" observed by a Canadian military physician began the quest for their identity and significance. The find led to identity of the X-chromosome that forms females. The Y-chromosome, which drives a foetus to become a male, was a later discovery.
In Sykes' view, the human male's chromosome has been the major factor in human evolution and cultural development. Not only determining gender, it acts through a feedback loop. More powerful, aggressive males tend to reinforce their role in selecting mates and propagating traits in offspring. While the Sykes' progenitor has nearly ten thousand descendants, the MacDonald clan, long dominant in Scotland, has proliferated around the planet with nearly half a million progeny. The most numerous progeny, however, has resulted in 16 million descendants of Asia's Ghengis Khan scattered throughout Eurasia. The Khan is the most extreme example of the male's propensity for war, conquest, and, in Sykes' view, the "enslavement" of women. His descent into the depths of "political correctness" is brief and shallow, but telling for his thesis.
Today the planet is carpeted with humanity, the result of a society dominated by the Y-chromosome. When hunter-gatherer societies took up agriculture, it "chained women" to "serial pregnancies", depriving them of the "relaxation of a sedentary existence" while producing additional farm workers. The resulting population explosion ultimately drove the creation of our industrialized, polluting society. This condition, in Sykes' view, is now leading to a depletion of the Y-chromosome's prowess. Ultimately, he argues, human males will be replaced by a society of women. Whether men will be kept as breeding stock he doesn't predict.
A practiced adept at metaphor, Sykes' finesse in describing cellular mechanics is unusual in a scientist. He portrays a slow-motion ballet, with chromosomes gently finding their opposite number to "delicately lie alongside each other" until "they are entwined". It's very sensuous genetics. The tone changes when he portrays the head of a sperm entering an egg. The ensuing scene is a battle reminiscent of a Hollywood war film. Mitochondria launch vicious assaults on invaders, slaughtering whatever can be attacked. One wonders how conception ever occurs. It does, of course, but he makes clear that a decline in success is inevitable.
Although Sykes builds a compelling case for the roots of our society's ills, there are too many ignored aspects. He challenges the recent paper by a team demonstrating the Y-chromosome's prowess at self-repair. His arguments require further study, but his adamant insistence smacks of desperation, not evidence. Although this book is a valuable study, there's more work to do. With so much of human evolutionary history to be assessed, we can consider this an important, but not a final, step. [stephen a. haines - Ottawa, Canada]