Randell Roberts, age 10, of Iowa Falls, Iowa, for his question:

What exactly is hair made of?

They keep telling us that hair is made of protein. This seems odd because we also hear that protein is muscle and meaty food. Actually, there are many protein chemicals and every living cell needs a variety of different ones. Some proteins dissolve in moisture and help the cells do their work. Others are gooey gelatins and others form soft or hard walls around animal or plant cells. Certain very tough proteins are used to build fingernails and claws, hoofs, hair and fishy scales.

The basic ingredients in all these different proteins are carbon and hydrogen, nitrogen and oxygen. Some also have traces of phosphorous, sulphur or other elements. All proteins are polymer chemicals made from chains of small molecules called amino acids. Hair roots deep in the skin manufacture special cells almost entirely from tough, spongey proteins that refuse to dissolve in moisture. These long empty boxes are sealed together in ropey threads. Actually, hairs are made of dead cells because they have no nerves, no blood vessels and no living protoplasm.