Crying is not just an allergic reaction to sadness. Tears triggered by emotions have a different chemical composition compared to the tears our eye makes for lubrication (basal tears) or to flush away irritants (reflex tears). Emotional tears (psychic tears) contain higher levels of stress hormones and natural painkillers (endorphins).
Only humans appear to shed tears of sadness. Other animals and primates cry communicatively, and as distress signals, but they do not weep.
Adults are less likely to cry from physical pain than children but are more likely to indulge in sentimental sobbing.
**”Birds fly, and babies cry”. Most human babies will cry without tears until 2 to 4 months of age, and the average baby will cry about 2 hours per day during the first six weeks of life. Doctors set the diagnostic limits of crying by the “rule of three”. Infant crying, for no apparent reason, lasting >3 hours per day and occurring >3 days per week in an otherwise healthy infant ❤ months of age indicates infantile colic.
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