system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the biological purpose of crying when you’re sad?

Is there a purpose?
gpt
Aside from the answer given the other "biological" (I deem this as why evolution made it that way) is because it expresses sadness without any form of language. Like all of our muscles that allow us to make facial expressions tears help convey emtoions, which is incredibly useful for our species which has evolved with social ability in mind.