Crocodile Tears Are No Such Thing


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crying 4.jpgOver the weekend, I watched "Extremely Loud and Incredibly Close," with Tom Hanks.  In this movie, Oskar, Tom Hanks's "son", searches for a specific lock that can be opened by a key that he found in his father's closet after he was killed on 9/11.  Oskar meets a lady who ends up crying in front of him and he told her that humans are the only species that can cry.  I thought that this was very interesting and it surprised me a lot.  Why is it that humans cry? Is there a specific part of our tear ducts that allow for this?

                After doing some research I found that animals do cry; they just don't produce emotional tears that run down their faces like humans do.  There are three kinds of tears, two of which are present in all animals.  The first type of tears are basal tears, these are responsible for keeping the eyes wet and they form the protective film that is always present on the surface of the eye.  The second type of tears are reflex tears, which form when there is dirt or other types of substances that irritate the eye as a way to clean out the eye.  The third type of tears emotional tears, which are unique to only humans.  These tears are produced when physical or emotional pain occurs.

                Research has proven that there are different types of hormones that are present in emotional tears that aren't present in basal or reflex tears.  The hormones produced in emotional tears are the same ones often associated with moods.  This also explains why women cry more than men because woman have 60% more of these hormones than men do, according to Dr. William Frey, author of Crying: The Mystery of Tears.  When humans are in situations that typically result in crying, the levels of these hormones rise in the body, and crying is a way to balance these hormones out because the body naturally excretes the excess.  This was proven by a study done at the University of South Florida that concluded that 'crying it out' is actually beneficial for the body.  Jonathan Rottenberg, the leader of the study and an assistant professor of psychology at the University of South Florida, said that they looked at over 3000 cases of people who recently cried.  The majority of them reported that their mood was better after crying.  Only one tenth of the people analyzed said that they felt worse after crying.  Of course, this study was observational, so the results could be due to a variety of different things; you can never solely rely on someone's personal report of their mood in an unfamiliar setting.  Another problem with this study is that the researchers didn't specify what caused the crying episodes and if that had an effect on the way people felt after crying, or not.  Also, one tenth of the participants is 300 people, which seems like a lot to me out of the 3000 to report that they felt worse after they cried.crying 1.jpg

                According to Dr. Provine, a neuroscientist at the University of Maryland, humans are able to produce emotional tears due to evolution.  He conducted a study where people rated how sad certain people looked in pictures.  The participants looked at real pictures of people crying and then at the same picture with the tears digitally removed.  When the tears were not present, the participants rated these people as not very sad at all, but rather confused or concerned.  From this, Dr. Provine concluded that emotional tears were 'created' through evolution to make human emotions clearer.  Without the actual physical tears, it is difficult for other humans to figure out someone's mood based on just their facial expressions.  When tears are apparent, it is obvious that some sort of pain is being experienced.  This study is also observational, but the participants are looking at photos of other people and the reason as to why they are crying is not important.  The bottom line of this study is that the tears were essential for the participants to correctly figure out the moods of the people in the pictures that they viewed.

                Other animals do cry, but they don't shed emotional tears.  When an animal is in pain, for example, they let out cries or howls, but no tears are shed.  Humans are the only type of 'animal' that actually shed tears as a way to express emotion; all other animals just create tears as a way to protect their eyes.  It is interesting to me that if crying is a natural way for the body to excrete hormones due to mood, why don't animals do this too?  Animals definitely experience sadness, pain, withdrawal, happiness, joy, etc., so why don't they need to produce tears to balance out their hormones?  If tears are due to evolution and a way to effectively communicate without words to other humans that someone is experiencing sadness or pain, how do animals know that their fellow animals are experiencing pain or sadness?  Are their facial expressions different?  Or do animals just sense that this is going on?  Or do other animals just not care?

**All sources used are in the links within the blog.

crying 3.jpg


3 Comments

My idea for why humans have developed the ability to cry is not so the emotions would be clearer, but so the excess of hormones would be released. I think that the body knows when it needs to release emotion, and its natural way to do that is to cry. The idea to show emotion clearer does not make much sense to me because it does not seem as important to survival that people can tell I'm sad. It may just be because I'm a guy though.

I am curious as to why some animals dont show emotion through their tears, mainly primates. I will not say whether I am a believer of evolution but if they can notice other traits that have evolved why have tears completely disappeared?

I've always wondered the same thing about animals and whether or not their tears are in anyway related to emotions. I have a mixed breed dog that is part cocker spaniel. He is ALWAYS crying, and it's kind of a running joke with my friends and family because he is literally the most spoiled dog on Earth but he is constantly crying.

I did a little research on my own to see why my little Oliver is constantly crying. Like you said, it's not due to emotional stress or physical pain, but rather is caused by other factors.

There are many different reasons for why dogs cry. One of those reasons is because they have shallow eye sockets or because of hair that grows around the eyes. In the case of my cocker spaniel, his breed (along with poodles) are more prone to have a clogged lacrimal puncta, which causes them to cry. This blockage is usually due to previous eye infections or scar tissue around the eye.

Take a look at the first link below. It provides a diagram of where these ducts are located (we know them more commonly as "tear ducts").

http://student.vetdoctor.ru/ftp/wendy/data/images/IM25000/IMC23203.jpg

http://pets.webmd.com/dogs/guide/dogs-and-tear-stains

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