【英语时差8,16】为何蛇类舌头分叉-上（在线收听）

Why do snakes have forked tongues? And why do they flick them? Is it because snakes are naturally deceitful, ready to whisper lies into passing ears? Actually, it’s to aid a snake’s vomeronasal system-a sensory system in snakes that is akin to smell. Snakes have forked tongues so that they can "smell" in stereo. What Exactly Does This Mean?What does it mean to sense anything "in stereo?" If you listen to music holding only one side of your headphones to your ear, the whole orchestra sounds like it’s crushed into one, tiny speaker. If you put your headphones on correctly, using both ears, the music becomes more three- dimensional. Likewise, it’s easier to judge the depth of a scene with both eyes open than with only one.