memes

You can’t do that when things are above/below.

You obviously have never been near a tree with a singing bird in it. You can definitely tell that the sound comes from above. That’s because the shape of the outer portion of the ear somehow funnels the sound in a way that makes it possible for the brain to determine the origin of the sound.

I am going to make a guess here, but I think humans might not even require this, we are farely unique (not unique per se, but it is rare i think (just primate family)) in our height class, higher than most quadraped stuff, but not high enough to be of the size of trees, so most noise either comes from above us, or below us, or at same height as us, and mostly heights coming from our own height usually would not be scary. And at small enough distances, we could easily tell source of noise from above or below (purely by being practised to know what source could produce what intensity at what distance) and at a longer distance where the difference would be small (relative to each other) we as may as well consider them same and treeat them same. All hypothesising, but I would guess we would loose the need quickly enough, considering tilting would mess up with our usuall visual processing, which we do much better, it would not be useful to hurt our better skill for something not useful