The Paradox of Crying Babies

Crying is the earliest and most compelling of infant signals," writes Ronald Barr, and surely there is no sound on earth more piercing than the cry of an infant. The ability to cry was hard-wired into human babies long ago as a potent signal to get adult attention. Like other primates, human infants needed to be able to send a message of distress to motivate action on the part of someone more able. The same kind of vocal signals are found in Rhesus monkeys, for example, which have very distin...