"Sudden loud noise triggers a cluster of split-second protective reflexes known as the startle pattern. You blink to protect your eyes, while your upper body swivels toward the sound to assess the threat. The arms bend and retract to the chest, the shoulders hunch, and the knees bend, all of which combine to make you a smaller, less noticeable target. Snapping the limbs in tight to the torso may also serve to protect your vital innards.++ You are your own human shield. Siddle says hunching may have evolved to protect the neck: a holdover from caveman days. "A big cat stalking prey will jump the last twenty feet and come down on the back and shoulders and bite through the neck."