You’re watching the final scene in Thelma and Louise, and you’re on your third handkerchief. You turn your tear stained face to the side and look through blurred, saline-flooded vision at your cat, who is staring back at you witnessing the curious spectacle. Why is it that humans can be reduced to blubbering messes, while other members of the animal kingdom don’t seem to let out even a sniffle?

We have tear ducts to lubricate and protect our eyes from dust and other particles. The ducts are under the upper eyelids and produce a salty liquid—a tear-–-that gets spread throughout the eye after each blink. Animals too have the ability to produce tears, but not necessarily for the same reasons that we humans produce them.

Three types of tears are generated by the human eye. Basal tears protect the eye and keep it moist. Reflex tears flush out the eye when it becomes irritated. And emotional tears flow in response to sadness, distress, or physical pain.

Studies have shown that emotional tears contain more manganese, an element that affects temperament, and more prolactin, a hormone that regulates milk production. Sobbing out manganese and prolactin is thought to relieve tension by balancing the body’s stress levels and eliminating build ups of the chemicals, making the crier feel better.

But this minor physiological benefit aside, the most likely reason we produce emotional tears is because it’s a means of communication. Before babies can speak, they can cry. The only way for infants to express frustration, pain, fear, or need is to cry. Adults may use crying to bond with other humans. Expressing sadness can prompt comfort and support from peers. Different languages can provide barriers to spoken communication, but emotions are universal. There are also culturally acceptable reasons for crying that bring people together, such as at funerals or weddings.

Though there is a significant debate over whether animals have emotions and can express them, some animals do appear to cry for emotional reasons. Elephants seem to grieve when a family member dies and will guard the body and travel long distances to view it. Elephant experts at the London Zoo once told Charles Darwin that the animals do indeed mourn. Chimpanzees also appear to cry, but some scientists still insist that the tears released by these animals are strictly for cleaning the eye.

Whether or not animals shed tears for emotional reasons has yet to be scientifically proven. Humans, however, can and do dissolve into tears for any number of reasons. Cleansing the eye, relieving stress, conveying pain, communication, and societal assimilation can all lead to an empty tissue box. So weeping after that sappy movie might not mean that you are a total wuss after all. In fact, it may mean that you are behaving like a perfectly normal human being.

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