as into the design and function of the human penis and cervix led to a number of scientific papers and an academic book: Human Sperm Competition: copulation, masturbation and infidelity. Noticing that sperm in a mixed sample tends to clump together—making it less mobile—and to have a high mortality rate, reproductive biologist Robin Baker, formerly of the University of Manchester, proposed about a decade ago that some mammals, including humans, manufacture "killer" sperm whose only function is to attack foreign spermatozoa, destroying themselves in the process. To test this idea, reproductive biologist Harry Moore and evolutionary ecologist Tim Birkhead of the University of Sheffield mixed sperm samples from 15 men in various combinations and checked for how the cells moved, clumped together, or developed abnormal shapes. "These are very simple experiments, but we tried to mimic what goes on in the reproductive tract," Moore says. The team found no excess casualties from any particular donor or other evidence of warring sperm, they report in 7 December Proceedings of the Royal Society. "The kamikaze sperm hypothesis is probably not a mechanism in human sperm competition," says Birkhead. The findings are "the nail in the coffin for the kamikaze hypothesis," says Michael Bedford, a reproductive biologist at Cornell University's Weill Medical Center in New York City. He says he had never given the idea much credence. Publications As well as being the author of around one hundred scientific papers and six academic books, Robin Baker is the author of four popular science books: Sperm Wars; Baby Wars; Sex in the Future; and Fragile Science. He has also written three novels: Primal; Caballito; and The Hitchhiker’s Child which under the guise of being sexual whodunits continue the theme of the evolution of human sexual behaviour. His first novel, Primal, was likened to both the TV series Lost and William Golding's Lord of the Flies. It describes a group of university students and staff stranded on a remote desert island occupied by feral chimpanzees. Bit by bit the people find themselves stripped of all the trappings of civilization until like the apes around them they have only their instincts to guide them. In Sperm Wars, Baker asserted the human cuckolding rate to be at 10% and that women frequently cheat to secure better genes for their offspring. This figure was later debunked, because studies which rely on a data set consisting of men who