The naked mole rat (so-called because it looks like a furless rat which lives in underground burrows) cannot feel the sensations mammals usually feel when exposed to hot substances (like chili) and acid-like tastes (like lemon juice). They are by no means immune to pain – poke them and they’ll feel as much pain as any human would – but the fact that these two sensations are missing is intriguing scientists.
Why are these peculiar animals (the only cold-blooded mammals) different to all others when it comes to pain? Scientists think they’ve tracked down both the physical adaptations, and the reasons for them. For example, a key neurotransmitter in the skin is missing in the naked mole rats, and nerve connections in their spinal cords are different to any other animal.
Possible reasons for these adaptations are that the animals live in colonies by the hundreds, so there is a large concentration of carbon dioxide, which becomes acidic when reacted with water. Maybe there was once an essential part of their diet that contained acid or capsaicin – the active ingredient in chili peppers.
So what are the implications for humans? By working out exactly why naked mole rats do not feel these pains, scientists could then adapt this knowledge to produce improved painkillers for humans. Also, the ability to block out only certain sensations would have many uses.
Naked mole rats really are quite interesting creatures after all…