Why is the sound of fingernails on a blackboard so irritating? This question may have been asked and answered but I was just curious.
The answer came to me like a blinding flash. I once ate something at a picnic which I’d dropped on the ground and then cleaned off. (Oh, you do SO do it too!) Suddenly, as I was chewing, I heard SKKKKEEEEEECH!!! as I bit down hard on a tiny stone. I think every single hair on my body stood on end, and my jaws froze instantly.
THAT’S IT! Fingernail-on-blackboard sounds exactly like permanent tooth destruction. It’s the high-frequency violin-like waveform of hard surfaces moving with stick/slip motion. Nobody realizes this because we’re too damned civilized, and we rarely have rocks in our food anymore. But when we bite down on something which is far harder than tooth enamel, our instinctive programming instantly informs us in no uncertain terms. Sensible? Flesh heals, but teeth do not. Skin is full of nerve endings, but the thick outer layer of teeth lack feeling. Animals need something besides pain to inform them that they’re damaging themselves in a permanent way. Well, I think it’s a much better theory than the Macaque warning calls. And I haven’t seen it written down elsewhere.
Scraping your fingernails on blackboards is telling the reptilian brains of all the surrounding humans to STOP BITING THAT ROCK! NOW!!!
Ooo! Maybe that’s why ears evolved to be near jawbones. If they tended to be much farther away, that horrible noise of squealing enamel wouldn’t be so loud.
Also, if you want to give yourself the willies, imagine biting down hard upon a smooth, dry pebble while grinding your teeth back and forth on it. The surface of the pebble is just like slate, but it’s not your fingernails making the noise. Yeesh! For me it’s like visualizing razor blades across the eyeball (another instinctive avoidance algorithm. Heh.)
bbeaty, that made a whole lot more sense than I thought it did when I started to read it.
Now that I think about it, this might also explain the reason for “baby teeth.”
If pain doesn’t work well, and your instincts and biology have to TEACH you not to bite down hard on on rocks… then it will take some time for you to get the hang of it. But with teeth, you only get one chance.
A human who has several “multiple dentitions” might get into trouble during the times their old teeth are falling out and the new ones haven’t yet grown back. But there might be one instance which would give an overall payback: the months of learning during childhood. Hey, you get a cheap set of teeth to destroy before the long-term ones appear.
All speculation, of course.
If I’m right, then someday the trivia experts will know that there’s a connection between fingernails on blackboard, the position of human ears, and baby teeth.