Preface
While researching literature for a paper on silvered leaf monkeys, a Malaysian species, Lee Harding discovered that infanticide by males, long reported as a common behavior of this species, had never actually been observed. In the 1970s, the original author of the report had assumed that it might have occurred because of a new theory then sweeping the nascent field of sociobiology: that when taking over a troop of monkeys or a pride of lions, males often killed the infants, ostensibly to bring the female into estrus so that he could mate with her. The theory had been put forward in 1974 based on observations of hanuman langurs, a South Asian species of leaf monkey, as well as on solid biology: Primate females who are nursing do not ovulate: they come into estrus, and hence become willing to mate, only after their infants are weaned or killed. Later research confirmed that infanticide has adaptive advantages in some hanuman langurs (Borries, Launhardt, Epplen, Epplen, & Winkler, 1999). However, Harding realized that the biology of silvered leaf monkeys precluded any such benefit to the males, for reasons explained in chapter 10.
Knowing that Anne Innis Dagg had been involved in the scientific controversy about male infanticide—whether and how often it occurred, whether it could have an evolutionary basis—that was debated in journals