Why Babies Beam

After boasting about their newborn's first smile, many proud parents are deflated by the pediatrician's cool remark: "It's only gas." Not so, says Psychiatrist Robert N. Emde of the University of Colorado School of Medicine. Having studied more than 300 beaming babies in the past nine years, Dr. Emde reports that infants have two quite different kinds of smiles, neither of which has anything to do with gas.

Even before a baby recognizes faces or responds to voices, says Emde, he smiles when he is drowsy or wriggling in his sleep. During his first two weeks of life, such grins occur as many as nine times per 1 1/2 hours of sleep. By comparing the brain-wave patterns of normal, severely retarded, and premature babies, Emde found that sleepy smiles at this age are caused by an internal stimulus--the growth of the brain stem, a primitive portion of the brain not directly involved in sight or thought.

According to Emde, a normal baby does not begin to smile in response to external stimuli--even a father's funniest faces--until the age of at least three weeks. Inward-growth grins still occur at 2 1/2 months. But then comes a shift; if the child is awake and not crying, he tends to smile at comforting sights, sounds and touches. Soon his grins are triggered almost entirely by outside things, especially familiar faces. Secrecy is replaced by sociability--and parents finally get back smile for smile.

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