It turns out there are real people eager to cut their healthy limbs off.
This is not typical pastime, of course. The condition is called Body Integrity Identity Disorder.
This is relatively new discovery, however, scientists already put in in the same basket with anorexia and gender identity disorder.
At first, the condition was thought to have psychological roots, i.e. lying in the Zigmund Freud’s area of father’s penis envy.
However, recent studies confirmed this has a neurological basis, turning the folia into a disease. Every disease should have a proper latin name, so BIID got one. That is apotemnophilia. However, the -philia ending somewhat still traces it to Freud.
Anyway, the studies showed some abnormal function in the brain areas, responsible for mental image of the patient’s body. The the sensory information from the unwanted limb does not generate impulses in this brain part. That means the patients literally do not feel this limb belongs to them. They do not associate that as their own body part, and that’s why they want it amputated.
That’s the basic idea. As already said, the area is very new and only starts getting scientific attention. Hope the docs will find away to help those poor fellas. If not, who know, maybe amputee will start getting life transplants instead of dead ones?