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Crying is the shedding of tears in response to an emotional state. The act of crying has been defined as "a complex secretomotor phenomenon characterized by the shedding of tears from the lacrimal apparatus, without any irritation of the ocular structures".〔 Quoted by Michelle C.P. Hendriks, A.J.J.M. Vingerhoets in ''Crying: is it beneficial for one's well-being?''〕 A related medical term is lacrimation, which also refers to non-emotional shedding of tears. Crying is also known as ''weeping'', ''wailing'', ''whimpering'', and ''bawling''. For crying to be described as sobbing, it usually has to be accompanied by a set of other symptoms, such as slow but erratic inhalation, occasional instances of breath holding and muscular tremor. A neuronal connection between the lacrimal gland (tear duct) and the areas of the human brain involved with emotion has been established. There is debate among scientists over whether or not humans are the only animals that produce tears in response to emotional states. Charles Darwin wrote in ''The Expression of the Emotions in Man and Animals'' that the keepers of Indian elephants in the London Zoo told him that their charges shed tears in sorrow. Tears produced during emotional crying have a chemical composition which differs from other types of tears. They contain significantly greater quantities of the hormones prolactin, adrenocorticotropic hormone, Leu-enkephalin,〔Skorucak A. "The Science of Tears." ScienceIQ.com.〕 and the elements potassium and manganese.〔 ==Function== The question of the function or origin of emotional tears remains open. Theories range from the simple, such as response to inflicted pain, to the more complex, including nonverbal communication in order to elicit altruistic behavior from others. Some have also claimed that crying can serve several biochemical purposes, such as relieving stress and releasing toxins from the body. Crying is believed to be an outlet or a result of a burst of intense emotional sensations, such as agony, surprise or joy. This theory is more plausible as it explains why people cry during cheerful events, as well as very painful events.〔"Crying; The Mystery of Tears" (personal page of Frey WH with quote from his book )〕 Individuals tend to remember the positive aspects of crying, and may create a link between other simultaneous positive events, such as resolving feelings of grief. Together, these features of memory reinforce the idea that crying helped the individual. In Hippocratic and medieval medicine, tears were associated with the bodily humors, and crying was seen as purgation of excess humors from the brain.〔Lutz (2001), 69ff.〕 William James thought of emotions as reflexes prior to rational thought, believing that the physiological response, as if to stress or irritation, is a precondition to cognitively becoming aware of emotions such as fear or anger. William H. Frey II, a biochemist at the University of Minnesota, proposed that people feel "better" after crying due to the elimination of hormones associated with stress, specifically adrenocorticotropic hormone. This, paired with increased mucosal secretion during crying, could lead to a theory that crying is a mechanism developed in humans to dispose of this stress hormone when levels grow too high.〔(【引用サイトリンク】accessdate=30 January 2015 )〕 Recent psychological theories of crying emphasize the relationship of crying to the experience of perceived helplessness. From this perspective, an underlying experience of helplessness can usually explain why people cry. For example, a person may cry after receiving surprisingly happy news, ostensibly because the person feels powerless or unable to influence what is happening. Emotional tears have also been put into an evolutionary context. One study proposes that crying, by blurring vision, can handicap aggressive or defensive actions, and may function as a reliable signal of appeasement, need, or attachment.〔(''New Theory for Why We Cry'' )〕 Dr. (Oren Hasson ), an evolutionary psychologist in the zoology department at Tel Aviv University believes that crying shows vulnerability and submission to an attacker, solicits sympathy and aid from bystanders, and signals shared emotional attachments. Another theory that follows evolutionary psychology is given by Paul D. MacLean, who suggests that the vocal part of crying was used first as a "separation cry" to help reunite parents and offspring. The tears, he speculates, are a result of a link between the development of the cerebrum and the discovery of fire. MacLean figures that since early humans must have relied heavily on fire, their eyes were frequently producing reflexive tears in response to the smoke. As humans evolved the smoke possibly gained a strong association with the loss of life and, therefore, sorrow. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Crying」の詳細全文を読む スポンサード リンク
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