WHY can't people breathe and swallow at the same time?

 Humans have a unique vocal apparatus that distinguishes them from animals, in that it does not allow for simultaneous breathing and swallowing. The epiglottis, a supraglottic cartilage located behind the root of the tongue, closes the entrance to the larynx during swallowing to prevent food from entering the airway. When breathing, the epiglottis opens to allow air to flow into the larynx and then through the respiratory tract.