ON FERTILE GROUND: A Natural History of Human Reproduction

Fertility is undoubtedly the least often discussed facet of the reproductive process, in large part because scientists haven't had the tools needed to study it until recently, but also because, well, it's just not very sexy. But as Ellison, professor of anthropology and dean of the Graduate School of Arts and Sciences at Harvard, shows in this comprehensive study, fertility plays a far more important role than the sexual act in our development as a species. "It may well be... that it was an adaptation in our reproductive physiology that originally set the stage for our intellectual and cultural development," he asserts. But important aspects of female physiology aren't obvious outcomes of natural selection: the head size required for the relatively large fetal brain played a major role in the high incidence of women's death in childbirth in earlier centuries. The author tells us that scientists have discovered that there seems to be little correlation between sperm counts and male fecundity. One man can have the minimum normal sperm count of 15,000–20,000 per milliliter and another an astonishing 250 million, but both face roughly the same odds of impregnating a fertile egg. Ellison tilts perhaps a little too strongly toward female fertility; males receive only one relatively short chapter. The book is not an easy read and will probably appeal mainly to professionals in medicine and related fields. Still, any reader will be astounded not only by how much has been learned about human fertility but by how much still remains to be explored. (Mar.)