The shedder of tears is likely to apologize, even when a devastating tragedy was the provocation. The observer of tears is likely to do everything possible to put an end to the emotional outpouring. But judging from recent studies of crying behavior, links between illness and crying and the chemical composition of tears, both those responses to tears are often inappropriate and may even be counterproductive.
People are the only animals definitely known to shed emotional tears. Since evolution has given rise to few if any purposeless physiological responses, it is logical to assume that crying has one or more functions that enhance survival.
Although some observers have suggested that crying is a way to elicit assistance from others (as a crying baby might from its mother), the shedding of tears is hardly necessary to get help. Vocal cries, whines or whimpers such as animals use would have been quite enough, more likely than tears to gain attention. So, it appears, there must be something special about tears themselves.
Meanwhile, researchers at several other institutions are investigating the usefulness of tears as a means of diagnosing human ills and monitoring drugs.
At Tulane University's tear analysis laboratory Dr. Peter Kastl has found that ''like blood and urine samples, tears are an easily obtainable body fluid with a complex chemistry that is altered by disease.'' He and his colleagues report that they can use tears to detect drug abuse and exposure to medication, to determine whether a contact lens fits properly or why it may be uncomfortable, to study the causes of ''dry eye'' syndrome and the effects of eye surgery, and perhaps even to measure exposure to environmental pollutants.
Tears are produced continuously by the tiny lacrimal glands in the upper, outer corners of the eyes, under the lids. Every time you blink (on average 13 times a minute) your eyelids carry a film of tears across the corneas. An oil produced by other eye glands helps the tears adhere to the corneas, keeping them from drying out. The windshield-wiper effect of the blink also helps to cleanse the eyes of debris and irritating chemicals and perhaps even to fight infection, since tears contain antibacterial enzymes.
Tears that do not evaporate leave through the lacrimal canal and sac at the inner corner of the eye. From there they drain through the nose, which is why you usually have to blow your nose when you cry. Tears shed down the face represent an overflow of the lacrimal ducts, as might happen to gutters during a downpour.
Some people produce inadequate or abnormally concentrated tears. These victims of dry eye syndrome develop such symptoms as dryness, itching and burning, sensitivity to light and blurred vision. For many, visual acuity gradually worsens. Frequent use of artificial tears (sold in pharmacies without prescription) helps to relieve dry eye symptoms. However, frequent use of eyedrops designed to reduce redness is not advised.
Crying also seems to serve as a means of communication for babies before they learn to talk: Mothers soon learn to distinguish between cries of pain, fear and hunger, and those of crankiness. However, the actual shedding of tears is not needed to get the message across: Newborns cry without tears for the first few weeks of life.
Furthermore, children who are unable to shed tears because of an inherited disease called familial dysautonomia suffer severe reactions to even mild stress: They sweat profusely, drool and break out in skin blotches. Psychotherapists have occasionally described patients under stress who develop skin disorders that disappear when they are finally able to cry it out.
If the theory that tears relieve stress is correct, how does one account for tears of joy? Traditional explanations are that crying at graduations, weddings and happy endings really reflects unhappy feelings, such as the ''loss'' of a child to a new spouse or anxiety about the child's future. However, a more likely reason is simply that tears of joy are a response to intense emotion, which is stressful whether the feeling is sad or happy.
For adults to stop telling children things like ''Now, now, don't cry'' and ''Big boys don't cry.'' Crying is a natural phenomenon and the withholding of tears appears to be a danger to health.
