The Better Angels of Our Nature: Why Vio - By Steven Pinker Page 0,256

would bring you a son-in-law. Families with more sons would trade some of them for daughters-in-law and vice versa. True, your son-in-law’s parents might prefer him to stay with them, but you could use your bargaining position to force the young man to move in with you if he wanted to have a wife at all. A preference for sons should arise only in a market with distorted property rights, one in which parents, in effect, own their sons but not their daughters.

Hawkes noted that among foraging peoples, female infanticide is more common in patrilocal societies (in which daughters move away to live with their husbands and in-laws) than in matrilocal societies (in which they stay with their parents and their husbands move in with them) or in societies in which the couple goes wherever they want. Patrilocal societies are common in tribes in which neighboring villages are constantly at war, which encourages related men to stay and fight together. They are less common when the enemies are other tribes, and the men have more freedom of movement within their territory. The internally warring societies then fall into a vicious circle in which they kill their newborn girls so their wives can hurry up and bear them more warrior sons, the better to raid other villages, and to defend their own villages against being raided, for a supply of women that had been decimated by their own infanticides. The warring tribes in Homeric Greece were caught in a similar trap.130

What about state societies like India and China? In state societies that practice female infanticide, Hawkes noted, parents also own their sons but not their daughters, though for economic rather than military reasons.131 In stratified societies whose elites have indivisible wealth, the inheritance often goes to a son. In India the caste system was an additional market distorter: lower castes had to pay steep dowries so their daughters could marry higher-caste grooms. In China, parents had a permanent claim on the support of their sons and daughters-in-law extending into their dotage, but not of their daughters and sons-in-law (hence the traditional adage “A daughter is like spilled water.”)132 China’s one-child policy, introduced in 1978, made parents’ need for a son to support them in their old age all the more acute. In all these cases, sons are an economic asset and daughters a liability, and parents respond to the distorted incentives with the most extreme measures. Today infanticide is illegal in both countries. In China, infanticide is thought to have given way to sex-selective abortions, which are also illegal, though still widely practiced. In India, despite the inroads of the ultrasound-abortion chains, it is thought to remain common.133 The pressure to reduce these practices will almost certainly increase, if only because governments have finally done the demographic arithmetic and realized that gynecide today means unruly bachelors tomorrow (a phenomenon we will revisit).134

Whether they are new mothers in desperate straits, putative fathers doubting their paternity, or parents preferring a son over a daughter, people in the West can no longer kill their newborns with impunity.135 In 2007 in the United States, 221 infants were murdered out of 4.3 million births. That works out to a rate of 0.00005, or a reduction from the historical average by a factor of two to three thousand. About a quarter of them were killed on their first day of life by their mothers, like the “trash-can moms” who made headlines in the late 1990s by concealing their pregnancies, giving birth in secret (in one case during a high school prom), smothering their newborns, and discarding their bodies in the trash.136 These women find themselves in similar conditions to those who set the stage for infanticide in human prehistory: they are young, single, give birth alone, and feel they cannot count on the support of their kin. Other infants were killed by fatal abuse, often by a stepfather. Still others perished at the hands of a depressed mother who committed suicide and took her children with her because she could not imagine them living without her. Rarely, a mother with postpartum depression will cross the line into postpartum psychosis and kill her children under the spell of a delusion, like the infamous Andrea Yates, who in 2001 drowned her five children in a bathtub.

What drove down the Western rate of infanticide by more than three orders of magnitude? The first step was to criminalize it. Biblical Judaism prohibited filicide, though it didn’t go the whole hog: killing