Scientifically, tears are divided into three different types, based on their origin. Both tears of grief and joy are psychic tears, triggered by extreme emotions, whether positive or negative. Basal tears are released continuously in tiny quantities (on average, 0.75 to 1.1 grams over a 24-hour period) to keep the cornea lubricated. Reflex tears are secreted in response to an irritant, like dust, onion vapors or tear gas.
All tears contain a variety of biological substances (including oils, antibodies and enzymes) suspended in salt water, but as Fisher saw, tears from each of the different categories include distinct molecules as well. Emotional tears, for instance, have been found to contain protein-based hormones including the neurotransmitter leucine enkephalin, a natural painkiller that is released when the body is under stress.
Additionally, because the structures seen under the microscope are largely crystallized salt, the circumstances under which the tear dries can lead to radically dissimilar shapes and formations, so two psychic tears with the exact same chemical makeup can look very different up close. “There are so many variables—there’s the chemistry, the viscosity, the setting, the evaporation rate and the settings of the microscope,” Fisher says.
so similar, regardless of scale,” she says. “You can look at patterns of erosion that are etched into earth over thousands of years, and somehow they look very similar to the branched crystalline patterns of a dried tear that took less than a moment to form.”
The Microscopic Structures of Dried Human Tears
Photographer Rose-Lynn Fisher captures tears of grief, joy, laughter and irritation in extreme detail
By Joseph Stromberg
Image: http://blogs.smithsonianmag.com/artscience/files/2013/11/fisher_timelessreunion-copy.jpg
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