|MadSci Network: Evolution|
I'm afraid Terry I don't think I'll be able to give you anymore of a satisfactory answer than you have already received, as we are dealing with the evolution of an apparent abstract trait (like looking at a murder from the 1900's). We shed tears under two distinct situations; 1) where we are under emotional stress, 2) where we have some form of injury or irritation to the eye. The 2nd is easiest to answer first. In the event of injury or contact with the eye of a foreign object (substance) tears are released. These tears aid in the washing away of the foreign substance (cleaning the eye), but also contain lysozyme an enzyme which kills bacteria so preventing post injury infection. But this is not the focus of your question. The other reason for tears is a secondary effect to emotional stress. What evolutionary advantage would that provide well, a person who releases their stress is often able to deal with trauma greater than one who bottle up their feeling. Maybe in an evolutionary way those ancestors who released their feeling had a greater chance of finding a mate. As my degree is not in psychology I would bow to an argument that said my idea was incorrect from such as expert but feel it may have such reasoning.
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