You go to the supermarket and look around, and there you discover a lot of human food.
Ulf Dittmer wrote:Someone is curious enough to eat it. That person (or others, depending on the outcome) then observes the effects and draws conclusions.
If you want to find out if something is edible, find a dumb person and tell him: "Hey Joe! That red mushroom with those white dots looks delicious! Try taking a bite out of it!". If Joe than falls over and dies, you know you have to avoid it.