system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: When encountering dangerous aggressive animals, why is it so that you have to stare some species directly in the eyes while with others you have to break eye contact immediately or it will attack?
gpt
Some animals have the instinct to sneak up on and attack unsuspecting prey and don't want to risk an encounter with an animal that knows it's coming. 

Some animals have the instinct to respond to potential threats or rivals directly and perceive you staring it down as aggression toward it that needs to be dealt with.