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{{short description|Study of causation, or origination}}
{{distinguish|Etymology |Ethology |Ethnology|Entomology|Teleology}}
{{More citations needed|date=October 2015}}

'''Etiology''' ({{IPAc-en|ˌ|iː|t|i|ˈ|ɒ|l|ə|dʒ|i}}; alternatively spelled '''aetiology''' or '''ætiology''') is the study of [[causality|causation]] or origination. The word is derived from the [[Ancient Greek|Greek]] word {{Wikt-lang|grc|αἰτιολογία}} ''({{grc-transl|αἰτιολογία}})'', meaning "giving a reason for" ({{etymology||''{{Wikt-lang|grc|αἰτία}}'' ({{grc-transl|αἰτία}})|cause||''{{Wikt-lang|grc|-λογία}}'' ({{grc-transl|[[-logy|-λογία]]}})|study of}}).<ref>{{cite encyclopedia |title=aetiology |encyclopedia=[[Oxford English Dictionary]] |edition=2nd |year=2002 |publisher=[[Oxford University Press]] |isbn=0-19-521942-2}}</ref> More completely, etiology is the study of the causes, origins, or reasons behind the way that things are, or the way they function, or it can refer to the causes themselves.<ref>{{Cite American Heritage Dictionary|etiology}}</ref> The word is commonly used in [[medicine]] (pertaining to causes of disease or illness) and in [[philosophy]], but also in [[physics]], [[biology]], [[psychology]], [[political science]], [[geography]], [[cosmology]], [[spatial analysis]] and [[theology]] in reference to the causes or origins of various [[phenomena]].

In the past, when many physical phenomena were not well understood or when histories were not recorded, [[myth]]s often arose to provide etiologies. Thus, an etiological myth, or [[origin myth]], is a myth that has arisen, been told over time or written to explain the origins of various social or natural phenomena. For example, [[Virgil]]'s ''[[Aeneid]]'' is a [[national myth]] written to explain and glorify the origins of the [[Roman Empire]]. In [[theology]], many religions have [[creation myths]] explaining the origins of the world or its relationship to believers.

==Medicine==
{{Main|Cause (medicine)}}
In medicine, the etiology of an illness or condition refers to the frequent studies to determine one or more factors that come together to cause it. Relatedly, when disease is widespread, [[Epidemiology|epidemiological]] studies investigate what associated factors, such as location, sex, exposure to chemicals, and many others, make a population more or less likely to have an illness, condition, or disease, thus helping determine its etiology. Sometimes determining etiology is an imprecise process. In the past, the etiology of a common sailor's disease, [[scurvy]], was long unknown. When large, ocean-going ships were built, sailors began to put to sea for long periods of time, and often lacked fresh fruit and vegetables. Without knowing the precise cause, [[Captain Cook|Captain James Cook]] suspected scurvy was caused by the lack of vegetables in the diet. Based on his suspicion, he forced his crew to eat [[sauerkraut]], a cabbage preparation, every day, and based upon the positive outcomes, he [[inferred]] that it prevented scurvy, even though he did not know precisely why. It took about another two hundred years to discover the precise etiology: the lack of [[vitamin C]] in a sailor's diet.

The following are examples of intrinsic factors:
* Inherited conditions, or conditions that are passed down to you from your parents. An example of this is hemophilia, a disorder that leads to excessive bleeding.
* Metabolic and endocrine, or hormone, disorders. These are abnormalities in the chemical signaling and interaction in the body. For example, Diabetes mellitus is an endocrine disease that causes high blood sugar.
* Neoplastic disorders or cancer where the cells of the body grow out of control.
* Problems with immunity, such as allergies, which are an overreaction of the immune system.<ref>{{Cite web | url=https://study.com/academy/lesson/etiology-of-disease-definition-example.html |title = Etiology of Disease: Definition & Example - Video & Lesson Transcript}}</ref>

== Mythology ==
{{Main|Origin myth}}
An etiological myth, or origin myth, is a [[mythology|myth]] intended to explain the origins of cult practices, natural phenomena, proper names and the like. For example, the name [[Delphi]] and its associated deity, ''[[Apollo|Apollon Delphinios]]'', are explained in the [[Homeric Hymn]] which tells of how Apollo, in the shape of a dolphin ({{tlit|grc|delphis}}), propelled [[Crete|Cretans]] over the seas to make them his priests. While Delphi is actually related to the word ''{{lang|grc-Latn|delphus}}'' ('womb'), many etiological myths are similarly based on [[folk etymology]] (the term ''[[Amazons|Amazon]]'', for example). In the ''[[Aeneid]]'' (published {{Circa|17&nbsp;BC}}), [[Virgil]] claims the descent of [[Augustus Caesar]]'s [[Julian clan]] from the hero [[Aeneas]] through his son [[Ascanius]], also called Iulus. The story of [[Prometheus]]' sacrifice [[trick at Mecone]] in [[Hesiod]]'s ''[[Theogony]]'' relates how Prometheus tricked [[Zeus]] into choosing the bones and fat of the first sacrificial animal rather than the meat to justify why, after a sacrifice, the Greeks offered the bones wrapped in fat to the gods while keeping the meat for themselves. In [[Ovid]]'s ''[[Pyramus and Thisbe]]'', the origin of the color of mulberries is explained, as the white berries become stained red from the blood gushing forth from their double suicide.

==See also==
* [[Backstory]]
* [[Bradford Hill criteria]]
* [[Correlation does not imply causation]]
* [[Creation myth]]
* [[Just-so story]]
* ''[[Just So Stories]]''
* [[Pathology]]
* [[Pourquoi story]]
* [[David Hume|Problem of causation]]
* [[Involution (esoterism)]]

== References ==
{{Reflist}}

== External links ==
* {{Wiktionary-inline|etiology}}

[[Category:Causes of conditions]]
[[Category:Cause (medicine)| ]]
[[Category:Origin myths]]
[[Category:Mythography]]
[[Category:Mythology]]
[[Category:Origins]]