Ralph Locke, age 10, of Brighton, Mass. for his question:

Why doesn't it hurt to cut hair and nails?

Pain is caused by little nerves that flash messages to the brain. If you touch a hot stove with your hand or sit on a pin, your brain gets this information in a split second and it takes immediate action to protect you. These pain nerves are all over the skin and even in the roots of your teeth. Without them, you would not know when your body was being damaged.

There are no pain nerves, however, in the hair or in the hard material from which the nails are made. There are none in the outer coating of the teeth, which is why a tooth does not hurt until the decay has bitten through the hard enamel and also why we visit the dentist twice a year to catch those cavities before they get deep enough to hurt.