Leaves and berries that can kill

Did you ever wonder how we know what tastes like what, what is nourishing and what can killed if you eat it?
It could only be possible if someone or a number of someones tried them. A lot many people must have died munching on to unknown leaves and berries.
The mind of the child works the same way. The world is all unexplored territory, mapped very poorly by elders and the society. A child often have only one way to learn the world, by exploring it first hand, often with very little frame of reference to take cues from. That means a lot of unknown leaves and berries, some of which are not just unpleasant, they can kill.
It happens in large quantities when your brain develops, from conception to 6 years of age. And it happens again when your body catches up, when are in your teens.
All of us have a slighty different vantage points when looking at the world - not every toddler finds a hot iron, not every prescooler meets a boxful of pills and potions, and not evey teen has a drug peddler in the neighbourhood. And it is unlikely that elders or the society has the same leaves and berries to help us with.
Learning is often a solitary exploration for younger children. For teenagers, it is group learning and peer learning, essentially a process of learnig from other explorers of the unknown like them.