by Cheyenne Tait – As winter rolls in, having returned to the University of Notre Dame in the Midwest USA, I am not at all surprised by the fact that it’s cold and snowing. However, what I am surprised by, what I’m always surprised by, is the small minority of the student population that walks around in shorts and a mere hooded sweatshirt in a blizzard!
I recently remarked about this to someone, to which they jokingly replied “Maybe they don’t have any cold receptors.” Which sent me off on a tangent. I wondered, could someone, or some organism, just not have cold receptors? Evolutionarily speaking – no. If you don’t have a cold receptor you won’t know if it’s cold, leading you not to seek shelter, leading to death. All organisms need to keep their bodies relatively stable, relatively near homeostasis, and doing away with receptors that allow them to do that is not going to work.
But in fact, there is a rare human disease that makes it impossible to feel cold. Or heat. Or pain. It’s called congenital insensitivity to pain (CIP), and includes insensitivity also to extreme heat or cold. It’s extremely rare. And it’s debilitating, because wounds and infections go completely unnoticed by the person. Burns are apparently especially common, because children with this disease can lay their hand on something that’s too hot and not have the reflex to remove their hand.
Without being able to sense cold, heat, and pain, all important warning signs that let you know to change your behavior, life becomes very complicated, even for us as humans who are somewhat insulated from environmental forces with all our medical advances.
I was surprised to hear how closely related temperature sensing and pain are in humans, but after thinking about it for a while, I shouldn’t be. My face literally hurts when the temperature is below freezing outside and the wind is blowing, driving the “real feel” of the temperature even further below zero. Yet, still I have to walk to my lab. There is some evidence of acclimation abilities here though. We can become “used to” the cold, in that we feel the pain of it less. A study found that, on repeated exposure to extremely cold water, the self-reported sensation of cold and pain lessens.
So, rather than “not having cold receptors”, perhaps the students that I see in shorts are acclimated to the cold, more acclimated than I am, and don’t feel the pain that I would feel in shorts walking across a snowy campus.