WHY BABIES SCREAM
Like nails scraping a blackboard, or the rattle of a jackhammer, the cry causes great psychological distress in those who hear it, so they must spring into action and tend to the baby’s needs.
The first act that every healthy baby commits upon emerging from the womb is a cry — an expertly coordinated spasm of the diaphragm, with an exquisitely timed closure of the vocal cords across the windpipe (so that they vibrate and produce sound) and a synchronized opening of the mouth and lowering of the tongue:
Waaaahhh!
That newborns can, without a single rehearsal, perform this act of complex physical coordination upon first exposure to the air (before birth, all humans are aquatic animals) suggests that the infant cry is pure instinct, like the reflex kick of your foot when the doctor taps your knee with a hammer. And it has a clear, biological survival purpose: It ejects from the windpipe any mucous or amniotic fluid on which the baby could choke. But it also has a vital function as communication. It notifies everyone within earshot that the screamer is alive.
In the first days and weeks of life, the baby’s cry grows more robust as the abdominal muscles and diaphragm strengthen with use, and as
