Descended larynx: The human larynx is situated in the throat rather than the nasal cavity, a feature that is shared by some aquatic animals who use it to close off the trachea while diving; it also facilitates taking large breaths of air upon surfacing.[33] However, other terrestrial mammals, such as the red deer, also have a permanently descended larynx.[36] Humans also have a considerable amount of control over their breathing, which is an involuntary reflex for most terrestrial mammals.[27][33] Breath control is also thought to be preceded by bipedalism, which frees up the muscles of the upper torso from locomotion and allows breathing independent of limb position. Both of these adaptations are thought to derive from improvements in vocalization and the evolution of the ability to speak[4][37] and the human larynx is shaped differently from that of aquatic animals, predisposing humans to choking.[4]