The question of whether humans are becoming more brutal or more civilized has been debated urgently by the Athenians, the philosophers of the Renaissance, the Victorians and the existentialists. Those who argue that cruelty is currently becoming more acute point to the Rwandan genocide, global warming, and the malicious acts of selfish corporations and corrupt politicians. Contrariwise, others point to a safer and kinder society of greater prosperity and less prejudice against social, religious and ethnic minorities; Steven Pinker’s 2011 book, “The Better Angels of Our Nature,” proposes that we live more peaceably now than ever before. The dichotomous argument has particular resonance in the context of childhood. Teachers no longer routinely hit students; laws require accommodations for young people with learning disabilities; parents keep watch for teachers’ abuse and vice versa; developmental therapists are around every corner. Yet the Internet has unleashed meanness of a previously unimagined scope and celerity; broken households escalate children’s proclivity to launch unmonitored assaults on weaker kids; ethics are preached neither at home nor at school; and the accessibility of assault rifles enables nearly apocalyptic juvenile excess. Adult bullies from talk radio to Congress get constant airtime, and in many quarters their belligerence is applauded. Still, we are shocked when children behave belligerently toward one another. Youthful aggression has always been a problem and always will be; the pitilessness of childhood, like that of the world, is most likely a constant quantity.