Trypanophobia - Evolutionary Basis

Evolutionary Basis

According to Dr. James G. Hamilton, author of the pioneering paper on needle phobia, it is likely that the form of needle phobia that is genetic has some basis in evolution, given that thousands of years ago humans who meticulously avoided stab wounds and other incidences of pierced flesh would have a greater chance of survival.

The discussion of the evolutionary basis of needle phobia in Dr. Hamilton's review article concerns the vasovagal type of needle phobia, which is a sub-type of blood-injection-injury phobia. This type of needle phobia is uniquely characterized by a two phase vasovagal response. First, there is a brief acceleration of heart rate and blood pressure. This is followed by a rapid plunge in both heart rate and blood pressure, sometimes leading to unconsciousness. The loss of consciousness is sometimes accompanied by convulsions and numerous rapid changes in the levels of many different hormones.

Other medical journal articles have discussed additional aspects of this possible link between vasovagal syncope and evolutionary fitness in blood-injection-injury phobias.

An evolutionary psychology theory that explains the association to vasovagal syncope is that some forms of fainting are non-verbal signals that developed in response to increased inter-group aggression during the paleolithic. A non-combatant who has fainted signals that she or he is not a threat. This would explain the association between fainting and stimuli such as bloodletting and injuries as well as the gender differences.

Read more about this topic:  Trypanophobia

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