Nature’s Nether Regions: What the Sex Lives of Bugs, Birds, and Beasts Tell Us About Evolution, Biodiversity, and Ourselves

When writing about genitalia, it is difficult to find the correct balance between dry scientific description and pure titillation, but ecologist and evolutionary biologist Schilthuizen (The Loom of Life), in this remarkable book that explores the evolutionary origins of sex organs, succeeds in finding exactly the right tone. From a scientific perspective, there are obvious reasons for devoting considerable attention to this topic because “of all the organs that an animal is provided with, the greatest differences between species are... in their genitals.” Understanding the evolutionary pressures that have driven this diversity will yield insight into the ways of nature broadly across the animal kingdom, including humans. Schilthuizen deftly ties together research on the damselfly penis, with its spoon-like appendage used to remove sperm deposited in a current mate by a previous male, to research on humans that suggest the shape of the human penis might accomplish the same feat. On a more technical level he discusses the two dominant hypotheses to explain the underlying reasons for the evolution of genitalia: the “cryptic female choice” hypothesis, and the “sexually antagonistic coevolution” hypothesis. Schilthuizen’s entertaining work reminds us not to take “the mechanics of sexual intercourse for granted.” (May)