system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't dogs eat chocolate?
gpt
Stuff that shouldn't be in your blood is filtered out by your liver. If your liver can't do it, it might get damaged. Dogs (and cats) have livers that can't filter as many chemicals as people, so their livers get damaged, and livers are very important. In chocolate, the chemical that dogs' livers can't handle is called theobromine.

People have very good livers compared to most other animals, maybe because we have a very diverse diet (dogs nearly only eat meat normally).