Are Yawns Really Contagious?

Why are yawns contagious? Why do we hiccup? How do teeth get loose? Why do your ears hurt when you drive up over the mountains? Why do we get dizzy when we spin? Why do people slip? Why do people faint? Why do we have saliva and mucus? Why do people cry when they get hurt? How do voice boxes work? Why does your voice sound weird when it's recorded? Dr. Lori Racha has more answers to your body questions.