Etiology

Etiology (/iːtiˈɒlədʒi/; alternatively aetiology or ætiology) is the study of causation, or origination. The word is derived from the Greek αἰτιολογία, aitiologia, "giving a reason for" (αἰτία, aitia, "cause"; and -λογία, -logia). The word is most commonly used in medical and philosophical theories, where it is used to refer to the study of why things occur, or even the reasons behind the way that things act, and is used in philosophy, physics, psychology, government, geography, spatial analysis, medicine, theology, and biology in reference to the causes of various phenomena. An etiological myth is a myth intended to explain a name or create a mythic history for a place or family.

Mythology

An etiological myth, or origin myth, is a 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, Apollon Delphinios, are explained in the Homeric Hymn which tells of how Apollo, in the shape of a dolphin (delphis), propelled Cretans over the seas to make them his priests. While Delphi is actually related to the word delphus ("womb"), many etiological myths are similarly based on folk etymology (the term "Amazon", for example). In the Aeneid (published circa 17 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.

Etiology (medicine)

Etiology (/iːtiˈɒlədʒi/; alternatively aetiology) is the study of causation, or origination.

The word is derived from the Greek αἰτιολογία, aitiologia, "giving a reason for" (αἰτία, aitia, "cause"; and -λογία, -logia).

Description

In medicine, the term refers to the causes of diseases or pathologies. Where no etiology can be ascertained, the disorder is said to be idiopathic. Traditional accounts of the causes of disease may point to the "evil eye". The Ancient Roman scholar Marcus Terentius Varro put forward early ideas about microorganisms in a 1st-century BC book titled On Agriculture.

Medieval thinking on the etiology of disease showed the influence of Galen and of Hippocrates. Medieval European doctors generally held the view that disease was related to the air and adopted a miasmatic approach to disease etiology.

Etiological discovery in medicine has a history in Robert Koch's demonstration that the tubercle bacillus (Mycobacterium tuberculosis complex) causes the disease tuberculosis, Bacillus anthracis causes anthrax, and Vibrio cholerae causes cholera. This line of thinking and evidence is summarized in Koch's postulates. But proof of causation in infectious diseases is limited to individual cases that provide experimental evidence of etiology.