Introduction

In many societies people have been reported to kill infants of the ‘wrong’ sex. For most of these societies the ‘wrong’ or undesired sex is female. Female infanticide is well known in parts of India and China; it is also recorded in the Americas, Melanesia, many pre-modern European societies, and is thought to occur, or have occurred, in approximately 9% of the world's cultures (Minturn and Stashak 1982). Male infanticide is much less common, but has been reported for 2–3% of societies. Where infanticide is prohibited sexbiased investment in their children by parents is widespread. Sons and daughters, for instance, may experience differential provisioning: many African groups are reported as breastfeeding girls for longer than boys, while Asian, Latin American, and some European cultures seem to favour breastfeeding males for longer (Hrdy 1987:99). In societies with a strong son preference, combined with the technological means for reliable fertility control (e.g. Korea), parents pursue the ‘ideal’ family format of more sons than daughters via a sequential decision-making process (Park 1983).