Sperm Wars: The Science of Sex. - book reviews

Journal of Sex Research, Feb, 1998 by Michael W. Wiederman

Other writers have attempted to explain the function and evolutionary value of female orgasm, and typically concluded that female orgasm is an unintended evolutionary byproduct or evolved to strengthen pairbonds, (e.g., Fisher, 1992; Symons, 1979). Armed with more recent and relevant data, Baker describes how women's orgasms, although certainly not required for fertilization, can profoundly affect likelihood of conception. After describing at length the vaginal and cervical environments, Baker introduces the concept of a "cervical filter," referring to the type and amount of cervical mucus, cellular debris, ejected sperm, and other organic material. The strength of a woman's cervical filter fluctuates depending on various conditions, one of which is length of time since last orgasm. Orgasm (from masturbation, for example) results in a stronger cervical filter if performed 24 hours after intercourse than orgasm experienced 48 hours after intercourse. The strength of the cervical filter affects the relative ease with which sperm can reach the fallopian tubes, where fertilization typically takes place.

The story does not stop there. Through experiments conducted in his lab, Baker found that timing of female orgasm during or around the occurrence of vaginal intercourse further affects the likelihood of fertilization. During female orgasm the woman's cervix dips and the opening to the cervix gapes open, much like an elephant's trunk while taking in water. If a seminal pool is present in the vagina at that point, a significant number of sperm will be helped along by this "up-suck" phenomenon. So, to maximize conception, a woman should experience an orgasm immediately after a man ejaculates. If the woman experiences orgasm when a seminal pool is not present, vaginal secretions are likely to be "sucked up," thereby increasing the acidity of the cervical environment. Accordingly, female orgasm prior to male ejaculation strengthens the cervical filter and reduces the likelihood of fertilization. In this context, Baker also discusses the role of nocturnal orgasms in women's sexuality.

I was fascinated by this and other material in Sperm Wars, yet as I try to convey some of it here I am struck by how sterile the bare information seems. One strength of the book is Baker's ability to weave didactic coverage of material with his narrative scenes in which realistic sexual scenarios are used to provide a context for what the biological phenomena "look like," or actually how they play out, in real life. Accordingly, I encourage the reader of this review not to judge the book by my meager description.

Despite the praise I lavish on Baker and Sperm Wars, the book is not without its flaws and shortcomings. On a very minor note, there are several places where the reader encounters a British use of a word or phrase that an American is not likely to understand fully. On a conceptual level, those involved in the social sciences may feel as though something is missing. Baker's background is biology, so it should not be surprising that the book is weaker in providing psychological links between biological function and overt behavior. As just one example, Baker describes how men adjust the number of sperm in their ejaculate according to the proportion of time since last intercourse during which the man's partner was out of his sight (and hence potentially available for rival insemination). What is missing is an attempted answer to the fascinating questions of what psychological mechanisms are involved in performing such a "calculation" and what other relationship characteristics might affect the adjustment of sperm in ejaculate.