Evolutionary biology has been all the rage in the publishing biz over the past few years, as scientists have attempted to make their comparative studies of animal and human sexuality accessible to the general public. Robert Wright’s The Moral Animal and Helen Fischer’s The Anatomy of Love are two recent attempts to show how evolutionary forces have shaped and programmed our sexual behavior over the past several eons. British biologist Robin Baker’s Sperm Wars is one more voice added to the mix.

The book is a popular version of Baker’s earlier scientific writings published in Human Sperm Competition: Copulation, Masturbation and Infidelity. A lecturer in the biological sciences department at the University of Manchester, Baker is a man obsessed with sperm. In the introduction to Sperm Wars, he notes that nearly 100 couples have given him “nearly 1,000 ejaculates” so that he and his students could measure their sperm content. Couples collected samples from a variety of situations, including the post-coital dribble, or “flowback,” that runs down a woman’s leg and onto the proverbial wet spot.

Baker’s sperm obsession stems from the fact that less than 1 percent of all sperm are capable of fertilizing an egg. Scientists long believed that the other billions of nonfertile sperm men produce were merely defective. However, Baker and his colleagues discovered that nonfertile sperm serve a variety of functions in helping men compete in what he calls “sperm warfare.” The battleground for this warfare is inside a woman’s body. According to Baker, women engineer conditions in which sperm from different men wage war within their bodies so that the strongest ones win, ensuring the survival of the fittest. Men, on the other hand, produce armies of “kamikaze sperm,” which do nothing but prevent other men’s sperm from fertilizing an egg.

For sperm warfare to take place, lots of people have to be having sex with lots of different partners; Baker insists this is more common than most people want to acknowledge. According to surveys of British citizens, in their lifetimes about 80 percent of women have sex with two different men within five days, 69 percent within one day, 13 percent within an hour, and 1 percent within 30 minutes. As a result, Baker claims, a recent study in England found that 4 percent of all people are conceived via sperm warfare—one in every 25 British subjects.

Baker uses fictional scenes at the beginning of each of the book’s sections to portray just how sperm wars drive human behavior in real life. These tales are the stuff of the Penthouse Forum: sex with the TV repair man, older women seducing younger men, affairs on business trips, and a smattering of group sex, bisexual sex, gang rape, date rape, regular old predatory rape, masturbation, oral sex, and even just bored married sex. Many of the stories contain laugh-out-loud lines, like “His penis sensed action and began to stiffen into the rod of iron that hadn’t once let him down.” One pities Baker’s wife, who edited much of Sperm Wars; Baker says the book would have been much more graphic were it not for her help.

However ludicrous, each story has a moral, albeit an evolutionary one. Baker dissects each tryst into the various reproductive strategies at work, with an emphasis on evolutionary drives that are “hard-wired” into the human body. By the time you’ve finished the book, you’ll probably know more about the biology of procreation than you ever really wanted to. Baker provides detailed descriptions of insemination and orgasm (male and female), much of it based on new video footage captured by hooking up tiny cameras to research subjects’ private parts and watching them have sex—from the inside. Baker is clearly thrilled with this new technology.

But despite its physiological descriptions, one of Sperm Wars’ major flaws is that in attempting to make scientific theory readable, Baker has left out any reference to source materials. As a result, the reader is left to take the data presented on blind faith. Even so, Baker’s attempts to unravel the mysteries of human mating rituals are still worth plodding through.

One of the more fundamental questions he attempts to answer is, “What do women want?” Baker suggests that this age-old stumper has a biological root that is, in fact, far older. In a chapter titled “Learning the Gropes,” Baker explains that if men are to be successful from a reproductive standpoint, they must learn what makes women tick—no easy job, at least compared with what women need to know in order to sexually satisfy men. Baker has two explanations for women’s sexual inscrutability: First, human females differ from other animals because they show no physical signs of ovulation. By hiding their fertility, women benefit by forcing men to hang around, pay the rent, and attempt frequent sex in the hope of conceiving a child.

Second, Baker says women use sexual prowess as a test of a man’s genetic and reproductive potential, tossing out the sexually incompetent after his first fumble with the bra strap, forcing others to either stick around and study up or, ultimately, to use brute force to attempt to inseminate women. Women make use of these tests, he suggests, because their reproductive capabilities are far more limited than men’s.

Women’s interests lie in securing the best possible genes available for the few kids they can have, and also in retaining a good provider to ensure their health and longevity. According to Baker, women make subconscious trade-offs to achieve these goals. For instance, since female orgasm promotes conception, men who are good in bed are desirable mates. But sexual skill might not be such a good thing if a man has wanderlust or a sexually transmitted disease from screwing multiple partners, so women may tolerate (or train) less competent men because of their potential as long-term providers.

These are not either/or propositions, however; if they were, there would be no need for sperm wars. In his fictional accounts, Baker depicts women tricking men into supporting children who aren’t their own—gene-shopping through romps with the gorgeous young gardener while keeping Ward Cleaver close to home. This biological explanation for the “manipulative” woman stereotype won’t sit well with traditional feminists. However, Baker believes his research should dispel the myth of the sexual double standard. Women, he says, are biologically just as driven to philander as men, and deception skills are part of women’s powers. He also suspects that women’s drive to cheat may be the reason men have created chauvinistic social structures that prevent women from acting on the impulse.

Baker’s theories have social implications beyond traditional gender politics, especially in light of current debates over illegitimacy and welfare reform. For instance, in a chapter on contraception, Baker writes that the number of children a woman has depends not on the availability of contraception but on the perceived mortality rate of those children. If Baker is right—and a plethora of research suggests that he is—poor women have more children because fewer of them will survive to adulthood than those of women with more resources. Consequently, policies that result in starving the children of welfare mothers may only serve to increase the birth rate among that demographic group.

But Baker doesn’t apply his research to social policy—not much, anyway. He’s more concerned with the mechanics of sex and the ways in which people subconsciously prepare for sperm warfare, even if they aren’t engaging in it. Hence the chapters on masturbation, wet dreams, and oral sex.

After 300 pages of infidelity and debauchery, Baker concludes his treatise with an elderly couple watching over their growing family tree and happily contemplating the merits of a lifetime of mono-

gamy. He notes that monogamy can ultimately be the best reproductive strategy of all, but concludes that it is infidelity and other manifestations of sperm warfare that keep the species strong and diverse.

While Baker’s evolutionary biology is provocative, it still falls short of explaining all the complexities of human sexuality. Sperm Wars is sure to offend idealists, romantics, and those who cherish the notion of free will. Baker doesn’t allow for the possibility of conscious choices or such murky, emotional issues as love. And as Baker demonstrates, just as biology may propel positive social change by, say, providing a legal basis for gay rights, it can also be used as justification for all sorts of offensive behavior.

The proposition that we are forever at the mercy of our biology is unsettling, and in the end, it’s also unsatisfying, which in turn makes Sperm Wars somewhat unsatisfying. Baker never acknowledges the possibility that our brains have evolved along with our bodies to advance beyond the baser primal instincts. Wedded to his hard-wiring theory, Baker would take issue with Katharine Hepburn, who tells Humphrey Bogart in The African Queen that “Nature…is what we are put in this world to rise above.”