system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What exactly are dimples?

Some people have dimples on their cheeks, especially when they smile. Biologically what are dimples and what purpose do they have?
gpt
> Biologically what are dimples and what purpose do they have?

Dimples are caused by variations in the facial muscle zygomaticus major which for whatever reason is notched or doubled. There is no known biological role this plays.