Among the myriad of actions performed exclusively by humans, crying appears to be the most enigmatic. While no other animals are known to cry, humans shed emotional tears from birth throughout life.
The Evolutionary Purpose of Crying
In terms of evolution, crying seems to be an effective means of non-verbal communication. According to Why Only Humans Shed Emotional Tears: Evolutionary and Cultural Perspectives, there might not be any survival purpose for emotional tears; however, there is a strong relation between them and social expressions. The study mentions that crying is an "incidental result of certain emotions."
Evolutionary theories on crying have continued today. Ad Vingerhoets, who studies tears and their evolution in humans, explains the purpose of crying in Why Only Humans Weep (2013). In his work, he claims that crying elicits sympathy and help from others, which makes it evolutionarily beneficial in social settings. Based on this information, one can say that crying was beneficial for human groups in prehistoric times.
Emotional Tears vs Reflex Tears
Tears are not always alike. Tears due to irritants, such as smoke, are called reflexive tears, whereas those due to emotions are called emotional tears. According to the American Institute of Ophthalmology, more stress hormones are present in emotional tears than in reflexive tears. The act of crying can facilitate the regulation of stress by eliminating certain substances within the body. In this regard, crying could be a biological method of alleviating emotional stress. While the biological process involved remains unclear, this hypothesis explains why crying is both a psychological and physiological process.
Crying as Social Communication
One of the best examples of evolution is that crying helps with communication. The blurriness in vision caused by crying shows others how defenseless you are, thus asking for assistance while not showing aggression. Tears could evolve as a means of "honestly signaling submission, attachment, or need." This is one way crying is effective in creating connections and relationships, as mentioned in studies. Another reason crying might be effective is due to its importance during infancy. Infants do not have the ability to talk; crying is their only option when they require something.
Psychological Benefits of Crying
Apart from evolution, crying also helps maintain emotional wellness. Most people claim to feel relieved after crying, which is commonly referred to as catharsis. According to research, "Why crying does and sometimes does not seem to alleviate mood: a quasi-experimental study," crying has the potential to lift one's spirits, especially when followed by social support. As stated in an interview lecture, "One feels relieved after crying when they are given comfort and consolation." This confirms the belief that crying is inherently social, meaning it functions most effectively in the presence of others.
