Why do humans feel pain?

It may be hard to swallow just after stubbing your toe, but there is a purpose to pain, and a reason humans get it worse than most...
18 May 2015


Graphic of a woman with a headache


It has long been known that pain is necessary to avoid serious injury, but why do humans seem to get it worse than most animals? A new theory suggests it evolved stronger in people as a cry for help, as Max Sanderson explains... 

 Max: - So, the news piece I read was in the great New Scientist and it was by someone called Professor Barbara Finley and she was putting forward the argument as to why humans compared to our  primate cousins appear to have a heightened sense of pain. So, in evolutionary terms, pain is obviously very important to protect us from further damage and condition us to avoid certain situations, and also make other individuals aware that we need assistance. It's this, that she sort of focused on and she talked about how her time in the field were spent around quite a lot of primates and she was also a bit baffled as to, these monkeys who'd have caesarean sections and then within hours were sort of sitting up and climbing and playing. Having had two C-sections herself, it got her thinking that maybe humans unlike our monkey relatives have sort of evolved a mechanism whereby certain things such as giving birth, are deemed more painful for beneficial reasons. And so, she argued that these sort of heightened pain responses give us a sort of distinct advantage as humans that elicits a response from others, it means they'll come and give us assistance. So, giving birth to a child in humans can be very, very dangerous and so by heightening our levels or our perceptions of pain on the whole, it means that we demand to either have a midwife or a family member there and it means that hopefully, the mother and the child both have bigger chance of surviving. I just thought it was fascinating. Anything to do with pain, I'm generally quite - I mean study of pain. Not pain in itself, the study of pain.

 Chris: - Come on Max, be honest. When we were chatting about this early, you said you're quite into pain. And then you sort of said, "Maybe I should rephrase that."

 Max: - I can't believe I did it again I sort of made a note not to say that, but no, I'm into the study of pain.. it's a hugely fascinating thing because pain in itself is something that's completely created by our brain. Yes, there can be damage to a hand that you put on a hot stove in that sense, so it signals to the brain... but the pain in itself is something that we create as a reaction to that damage and so, it's highly sort of subjective.

 Chris: - I did interview a chap. It was a little while ago now, but Jeff Woods who's a researcher in Cambridge and he published a paper describing the genetic reason why there are certain families of people who live - I think these ones lived in Pakistan and Bangladesh - who are incapable of feeling pain. They lack a gene which normally would be used by the pain system in the body to trigger nerve impulses and these people don't have those receptors on their nerves. So, they can't trigger these pain responses and so they can do horrible things to themselves, and they frequently do, and they don't feel a thing. Isn't that awful?

 Max: - Yeah and that's the sort of nociceptors. It can be quite dangerous though because it means it doesn't give themselves time to heal.

 Kat: - Thanks very much. That's absolutely fascinating. You are listening to the Naked Scientists Q&A Special with me, Kat Arney.


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