Why Do We Cry?

Any parent cradling an inconsolable infant at 3 a.m. will tell you that tears are not always the clearest mode of communication. Indeed, expressing distress is but one part of the sob story.

• Basal tears (which flow continuously from the lacrimal glands) clean and lubricate the eye, making vision possible.
• Reflex tears clear the eye of irritants produced by, say, onion-slicing.
• Psychic or emotional tears are the complicated ones produced by babies and adults alike.

Believed unique to humans, emotional tears carry certain hormones and other proteins—produced during periods of stress— out of the body, which may explain the cathartic effect of "a good cry." But if the body is attempting to weep its waste away, tears are woefully ineffective; most get reabsorbed by the body. And none of this helps determine whether baby just needs to burp.

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