There are cases of people with no sense of pain. Here's an article about it:
http://findarticles.com/p/articles/mi_m1200/is_25_170/ai_n26713199/
...and a link to the primary it references, if you have a subscription to Nature:
http://www.nature.com/nature/journal/v444/n7121/full/nature05413.html
A relevant quote from the review:
"The team's first research subject, a 10-year-old boy, was well known in his community for street performances in which he placed knives through his arms and walked on hot coals. Despite tissue damage, he apparently felt no discomfort."
Other mutants for the same gene were similar -- they generally enjoyed showing off their lack of pain by deliberately injuring themselves. One killed himself by jumping off a roof, I believe just after the above article was published (sorry, I'm not really sure where I read that). Living without pain is generally an unhealthy idea. Without visceral negative feedback, humans don't place value on bodily integrity and tend to self-terminate, which is probably why those mutants are incredibly rare.
Perhaps once aversion reactions have been formed, knocking out pain receptors would be a good thing. I'd certainly be curious to see if people still avoid injuring themselves if they lose the ability to feel pain AFTER they've experienced it all their lives.
I'd certainly be curious to see if people still avoid injuring themselves if they lose the ability to feel pain AFTER they've experienced it all their lives.
They don't. People who develop pain asymbolia from various insults to the brain are not strongly motivated to avoid pain. (And these are people who have functioning nociception, unlike the family described in the article you link.)
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.