1. Hair is made up mostly of keratin , the same protein animals’ horns, hooves, claws, feathers, and beaks are made of. 2. When wet, a healthy strand of hair can stretch an additional 30% of its original length. 3. Hair grows slightly faster in warm weather, because heat stimulates circulation and encourages hair growth. 4. All hair is dead, with the exception of the hair that’s still inside the epidermis of your scalp. 5. Hair contains information about everything that has ever been in your bloodstream, including drugs, and is one of the most commonly used types of forensic evidence. 6. The only thing about you that can’t be identified by your hair is your gender—men’s hair and women’s hair are identical in structure. 7. Black is the most common hair color. Red is the rarest and only exists in about 1 percent of the world’s population, with blonde hair found in 2 percent. 8. As ...