system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that I have the ability to independently move one eyebrow but not the other?
gpt
Because they're 2 separate muscles controlling your eyebrows. Apparently this skill can be learned, but basically it comes down to some people's brains are able to independently control the muscles under your eyebrows, and some people's brains can't do it.