system
Given the following post, respond as if you're commenting on Reddit:
human
Why did we evolve ears? How did it happen?
gpt
Ears (the meaty flaps), or hearing?

The hearing evolved from otoliths in fish, which it was used to maintain balance/heading. These evolved to become vibration sensors in the jaws of reptiles, before migrating up through the skull into the system we have today. Various refinements happened along the way, such as the middle ear muscles that we have (but which birds don't), which clamp down when we chew, allowing us to eat food without deafening ourselves.