Any theory that relates emotional tears to infant crying must deal with two facts. Many infant primates make various crying sounds without shedding tears and are perfectly able to get parental attention. In the case the patient, referred to as Eloise, wept copiously from one eye at a time. If she thought of her mother, tears fell from her right eye, and if she thought of her father, tears fell from her left eye. Her therapists became fascinated with this phenomenon, and after some years of therapy, managed to get her to cry from both eyes when she was upset about anything other than her parents.
Emotional tears remain deeply mysterious.
If you can just get the funding, the field is wide open. And if you figure it out, I'll give you a salt-water fish. The Emotional Lives of Animals. All rights reserved.