July 2003

David Harris


Y: The Descent of Men by Steve Jones

In the 21st century, society's notions of gender are more complex than ever before. No longer can we talk about masculinity and femininity with the confidence in stereotypes that past generations had. But that is gender - what about sex? What does modern science tell us about what makes a male a male? And what does this mean for the human species? And how are sex and gender related? Nature or nurture? These are some of the questions that Steve Jones, professor of genetics at University College, London, tackles in his latest book, Y: The Descent of Men.

The enormousness of the field is daunting and choosing a path through this socially and politically loaded topic is unenviable. With so many books on gender already on the market, I was looking forward to a solid scientific exploration of genetics and the evolution of the male, as promised by all the promotion for this title. In this quest, the author is only partially successful, and never quite lives up to the promises of the blurb.

Jones begins promisingly, with a discussion of how the concept of sex evolved, some billions of years after life was well under way, and then launches into the evolutionary pressures that have caused there to be only two sexes rather than a multitude. He also gives an argument for why the sexes will tend to balance each other out in numbers, despite any new evolutionary or social advantage one sex acquires.

My only real criticism of Jones's opening sections on sex is that some of the arguments contain complexities and subtleties that could have benefited from the inclusion of some diagrams to assist in explanation. I am sure that professional geneticists will have no trouble understanding the details but those tackling these arguments for the first time might feel a little lost.

One cause of the difficulty is also a strength of the book. Jones includes a wealth of interesting anecdotes that are a delight to read but they can sometimes obscure the flow of a complex argument.

After the initial two chapters on genetics and evolution, Y moves on to discussions of male biology - how hormones affect us, the hydraulics of erections, and the effect of Viagra. All of this is pretty standard stuff, without any major surprises but again, the anecdotes are fascinating.

The focus then moves to the controversial topic of circumcision and castration. Jones correctly points out that of the arguments made for and against circumcision of boys are made for reasons other than the scientific. He states that circumcision brings a small health benefit for a minority of boys. However, the scale of this is much smaller than other more important health concerns. There are also dangers associated with the procedure, as for any surgery. Psychological effects also occur with reports of circumcised boys being less tolerant of the needle during vaccination a few months later. However, it is not clear that this effect is so significant as to warrant the statement in the blurb, "Circumcised boys are more frightened of injections than boys who have not undergone the operation." Perhaps any child's second medical procedure is more frightening than the first. Shouldn't we compare the needle given to a circumcised boy to the second procedure on an uncircumcised boy? This is perhaps a minor point but seeing as this issue is so contentious in some segments of society that it seems to warrant a very careful scientific approach rather than the more relaxed observation here.

Castration has a long and often odious history, commonly with religious or criminal overtones. However, results of studies done on castrated species show that there do seem to be health effects associated with the loss of the testes. Removal of the testes seems to lead to longer life and an enhanced immune system primarily due to a change in hormone balance. Unfortunately, castration is prescribed as a therapy for various types of offenders in the US. Jones is careful to tint his language to be scornful of some of the more reprehensible social consequences of uninformed and untested policies relating to sexual behavior and testes-related interventions but also states that independent of any ethical issues, there are indeed physical and psychological consequences to castration (whether physical or chemical) that may be useful in some way.

The biology of sperm and the social debates surrounding artificial insemination and sperm donation are discussed in a manner that seems to reflect the weight of scientific evidence, a criterion so often neglected by journalists. DNA testing, specifically in the context of parenthood determination, is the subject of an interesting chapter. The focus is on social aspects but some very important scientific points are made. Jones explains how DNA testing can be a very useful tool but that it is not sufficiently well understood by lawyers, judges and juries and there is much scope for misuse. As with most things biological, DNA testing is far more complex than we usually hear but it is precisely in those complexities that both the power and the danger of the technique lie.

Genealogical lines can be determined from testing of the Y chromosome but there are some difficulties due to the rapidity with which it can mutate. Significantly, particular patrilineal lines can die out very easily and it is also common for a single Y chromosome to become widespread in a society. This is one of the few hints in the book that provide evidence for one of the supposed major themes - that men are the second sex, in relative decline and in danger of being eliminated.

Jones goes into fascinating detail about how species use entirely different strategies for resource use and mating. For example, sometimes the male is the brightly colored attractive of the sexes, at other times it is the female. He ties the biological pressures to the interrelated social structures of various species. Sometimes the biology drives the society and sometimes it is the other way around. Often, the two develop hand-in-hand. Although there are complexities to the topic, Jones does an admirable job of conveying the main ideas without losing us in a messy collection of facts.

Toward the end, Y tackles the nature versus nurture debate. Jones convincingly argues that the majority of behavior is due to social environment but that genetics do have a significant influence on some aspects of this environment. He explains that there is typically far more diversity due to cultural effects than to genetics, and even that the majority of differences between sexes is environmental than innate. We cannot simply put all the differences between male and female behavior to the presence or absence of the Y chromosome. He dismisses the idea that the mere presence of a chromosome is responsible for criminality. Jones is more circumspect about whether there is such a thing as a "gay gene" but points out that social factors are likely to have a far greater impact and that there is definitely not a single gene influencing sexual preference. The contradictory research findings are mired in dubious methodologies and the difficulties in obtaining clear data.

In the last chapter of Y, Jones returns to the ostensible thesis of the book - that the male sex is in decline. The Y chromosome has been shrinking in size since it arrived suddenly on the scene, as a result of some random mutations. Yet, there is little other evidence for a biological decline. Rather, Jones is claiming that the decline of men is a social phenomenon.

Overall, the promotion for this book seems to have been quite misleading. Y is not arguing that the male sex is in decline (or at least does not argue this convincingly.) Instead, Y comes across as a book looking at genetics and sexual behavior, but primarily from a male perspective. In that sense, it is not particularly remarkable - we have an entire history of looking at science from a male perspective. Perhaps this book exists to counter recent publications looking at these issues from a female perspective.

There is no doubt that Jones' book is entertaining and enlightening but I was hoping that it would live up to its hype and spend more time on trying to explain just how the presence of the Y chromosome creates a difference between male and female genders. Alternatively, if the evidence is not there, perhaps there should be an upfront admission that genetics really doesn't give us the answers to questions of gender and that we should be looking to sociology for explanations.

Y - The Descent of Men by Steve Jones
Houghton Miflin
ISBN: 0618139303
252 pages