Why do we produce different types of tears?

The answer

Humans produce three distinct types of tears with different compositions. Basal tears continuously lubricate and protect the cornea with a complex three-layer structure of mucus, water, and oil. Reflex tears are produced in response to irritants like onion vapors, smoke, or wind, and contain higher concentrations of antibodies and antimicrobial enzymes. Emotional tears, unique among primates and possibly unique to humans, contain significantly elevated levels of stress hormones (adrenocorticotropic hormone and leucine-enkephalin), prolactin, and endorphins that are not present in the other tear types. This chemical difference supports the theory that emotional crying evolved as a self-soothing mechanism: by excreting stress hormones and triggering endorphin release, crying literally helps the body recover from emotional distress.