system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are us humans naturally afraid of the dark?

For example; when we're alone in the dark, in the stillness, we feel scared. We feel that there is someone behind us and our hearts being to race. Why do you think we're afraid? Why do we feel this way about the darkness, even if and when we know what's around us.
gpt
Because the night is long and full of terrors. At least it used to be. For the major part of our evolution as species, remaining alone in the dark long was a huge increase of chance of being horribly killed and eaten by a predator. It's also less safe to travel or do pretty much anything else whe  you can't see. Both seeing in the dark and instinctively avoiding it is thus an evolutionary advantage, and so we fear the dark.