Ophidiophobia, or ophiophobia, is a particular type of specific phobia, the abnormal fear of snakes. It is sometimes called by a more general term, herpetophobia, fear of reptiles. The word comes from the Greek words 'ophis' (ὄφις), snake, and 'phobia' (φοβία) meaning fear. Ophidiophobia, or ophiophobia, is a particular type of specific phobia, the abnormal fear of snakes. It is sometimes called by a more general term, herpetophobia, fear of reptiles. The word comes from the Greek words 'ophis' (ὄφις), snake, and 'phobia' (φοβία) meaning fear. About a third of adult humans are ophidiophobic, making this the most common reported phobia. A 2001 study at the Karolinska Institute in Sweden suggested that mammals may have an innate negative reaction to snakes (and spiders), which was vital for their survival as it allowed such dangerous threats to be identified immediately. A 2009 report of a 40-year research program demonstrated strong fear conditioning to snakes in humans and fast nonconscious processing of snake images; these are mediated by a fear network in the human brain involving the amygdala.A 2013 study provided neurobiological evidence in primates (macaques) of natural selection for detecting snakes rapidly. In non-medical press and literature, the movie-character Indiana Jones has been used as an example of someone with ophidiophobia, or just fear of snakes.