I've had a rather severe form of this phobia for as long as I can remember, which would suggest that not so much rooted in environmental reasons such as traumatic experience with needles (although I suppose it's possible this occurred in very early development).

Around 80% of people with trypanophobia have a close relative who also has it (II. Needle phobia: a psychological perspective - British Journal of Anaesthesia), suggesting a strong genetic basis. As far as I know none of my relatives share this.

Trypanophobia is co-morbid with anxiety disorders. I am diagnosed with OCD and autism as are some of my family members (especially OCD).

But what about evolutionary explanations for trypanophobia? It has been speculated that OCD, for example, may be a remnant of evolutionarily adaptive risk avoidance. The above article says this:

"Needles produce fainting; fainting is anxiety provoking; and anxiety produces feelings of being light-headed, sweaty, and blurred vision, which mimic the symptoms of fainting. The patient therefore gets into a vicious circle of avoiding the situation as the symptoms of anxiety convince them they are going to faint even before the procedure has begun. In an evolutionary sense, it would appear to make sense to decrease arterial pressure and heart rate when the subject has sustained a puncture injury, allowing for clotting to occur before the injured party bleeds out completely.^(4) However, despite the apparent evolutionary benefit, the process is very unpleasant for the patient and so avoidance is understandable."

Any thoughts/theories/papers?

Hello,

I'm a big fan of evolutionary psychology, and I was introduced to it by Jesse Bering's texts.

What I wonder if how we can know whether an aspect of humans or human psychology is necessarily an evolutionary adaptation, environmentally linked, or merely a genetic "defect" from genetic variation?

Here's some examples to explain what I mean:

A chromosomal disorder resulting in a stillbirth must surely be a genetic "defect." What would a species ever benefit from having stillbirths, besides evolutionary adaptations whose side-effect is stillbirths?

There's genetic evidence that depression is an evolutionary adaptation because some genes that cause depression also improves the immune system. (People who are depressed stay away from others and hence get sick less often.) Does this mean that all who experience depression with this gene have inherited a genetic adaptation? (https://www.theatlantic.com/health/archive/2012/10/the-evolutionary-advantage-of-depression/263124/)

In contrast, I could think of lots of reasons that ADHD is an evolutionary adaptation. (Different stimulus needs could produce different behaviors that are valuable for a tribe.) On the other hand, ADHD may be caused by a gene that prevents the body from properly digesting certain plastics. As a result, toxicity of these plastics could be responsible for ADHD. Does this mean that ADHD is an evolutionary adaptation or merely a result of our modern environment? (https://today.rowan.edu/news/2023/09/researchers-find-bpa-links-to-autism-adhd.html)

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If we are the mere products of the complex system of evolution, how can we know what aspects of ourselves are direct products that were beneficial to our ancestors versus mere variation or novel environmental factors?

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Edit: Corrected link for first article.