text: i can understand the purpose of two eyes (depth perception) and 2 ears (balance) but why do we have 2 nostrils   two nostrils coincide with the two hemispheres of the brain. studies have shown that by breathing through one nostril (holding the other one closed) can actually make one side more dominate for short periods at a time.   just remember that the nostrils effect the opposite brain hemisphere. so, closing your "left" nostril and breathing through your right will give your left-hemisphere (logical) dominance and visa-versa for the creative right-hemisphere.