Why do we cry?

It's not exactly clear why we cry, but there are various different theories which try to answer this puzzling question. It is suggested that women cry more than men, with women averaging out at 5.3 times per month, meanwhile men only cry on average about 1.4 times per month.

So, what are tears? They are chemically very much alike with saliva, as they contain protein, salts and hormones, but the components of tears vary dependent on the type of tear produced. There are three types of tears that can be produced. The basal tear keeps your eyes moist and lubricated. Reflex tears, are a response of the body to remove particulates from the eyes. Psychic tears, these are that we get when we are feeling upset or other overwhelming emotions.

Image from Cavs

Historically, the purpose of human beings crying was primarily for children, and when this process occurred, the parents could know that something is wrong and correct the issue. However, when humans reach adulthood, it is generally considered that crying is a weakness as it alerts others and predators to vulnerability. When humans and other mammals cry in pain, it allows others to be warned that there is danger.

But, one of the most intriguing questions here is, not why we cry when we are in pain, but why we cry when we are upset. The limbic system, which acts self consciously, works by using acetylcholine - a neurotransmitter. The limbic system deals with human emotion and can influence the production of tears so when we get upset we produce tears.

Furthermore, tears are known to contain leucine enkephalin, a pain-killer, which could suggest why your state of mind improves and clears after a good cry. Tears also contain lysozyme, an antibacterial enzyme which works by attaching itself onto the carbohydrate molecules on the cell wall effectively rupturing it and allowing water to move into the bacteria by osmosis causing the bacterium to swell until it eventually bursts. Moreover, crying is thought to reduce amount of manganese which can lead to tiredness, aggression, anxiety and nervousness. Also, reflex tears have twenty four percent more albumin protein which transports toxic molecules. It has even been proposed that tears can reduce stress levels.

For further information check out these sites (references):

• The science of tears 
• Interesting facts 
• Why tears are good for us
• Antibacterial tears