system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Since almost all of the water on earth is saltwater, why didn't we evolve to be able to drink it?
gpt
There was always enough fresh water around that we didn't have to. Things don't evolve because it would be a good idea, they evolve because if they don't they die. Not being able to drink seawater didn't kill enough of our  ancestors.