cover image The Other Big Bang: The Story of Sex and Its Human Legacy

The Other Big Bang: The Story of Sex and Its Human Legacy

Eric S. Haag. Columbia Univ, $35 (288p) ISBN 978-0-231-20714-0

In this stimulating debut inquiry, Haag, a biology professor at the University of Maryland, College Park, investigates the natural history of sex. He explains that “a limited form of sex” emerged two billion years ago, when primitive bacteria developed a means of exchanging genetic information with each other, resulting in superior progeny capable of withstanding corrosive by-products from the bacteria’s own oxygen metabolism. Sex enabled beneficial traits to spread quickly and facilitated microorganisms’ development into multicellular life-forms with specialized systems and cell types, including germ cells capable of producing sperm or eggs. Surveying modern creatures’ sexual diversity, Haag notes that hermaphroditic Pseudoceros bifurcus flatworms engage in “penis fencing” where both mates try to inseminate the other without being inseminated themselves; that mangrove killifish reproduce by “self-fertilization,” with each individual capable of generating both sperm and eggs; and that most bird sex involves both partners turning their internal reproductive anatomies inside out before touching them together. Though discussions of reactive oxygen species and electron transport chains make for dense reading, Haag’s illuminating analogies will help lay readers parse the jargon, as when he explains the evolutionary benefits of primitive bacterial sex by comparing it to stripping two junk cars of their best parts to construct one functional vehicle. This fascinates. (Nov.)