I had hoped you would also go into the types of tears that I and many cry much more often than from sadness, those being tears of joy. I always refer to my tears of joy as emotional releases. Perhaps as enjoyable as joyful feelings are, some joy can be so strong that it needs to be released, both because we are not supposed to exist for long in even natural euphoric states. Perhaps the release is also so the joy can be shared, yet, tears of joy are often misunderstood by those seeing them, and thus, they are not great signaling mechanisms.